Journal articles: 'OLEDs'

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Odedara, Nisha, Niteen Borane, Rahul Patel, and Rajamouli Boddula. "A Review on the Milestones of Blue Light-Emitting Materials in India." Organic Materials 5, no. 01 (January 2023): 1–20. http://dx.doi.org/10.1055/s-0042-1757980.

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Since 1987 in the field of optoelectronics, organic light-emitting diodes (OLEDs) have secured their position because of their extreme use in panels of lighting applications such as TV and smartphone displays. At present, OLEDs are at top-notch position in the lighting market for their promising features. The field of OLEDs is rapidly growing day by day in academia and industry due to the success of OLEDs in the form of excellent efficiency, feasible methods, excellent lifetime, color purity, and superb device architecture. As a result, OLEDs are new profitable leading devices of the 21st century. However, the OLED industry has evolved in optoelectronics in the last 30 years and is advancing rapidly just because of the development in OLED materials (fluorescent, phosphorescent, thermally activated delayed fluorescent, and blue light-emitting materials). Blue light-emitting materials have achieved incredible popularity nationally and internationally. At the international level, USA, Japan, Korea, and Germany are at the top of the list in the production of OLEDs. India has also seen rapid progress in OLED development in the last 12 years and details of research in blue OLEDs by key players of India are involved in this report.1 Introduction1.1 OLED Construction1.2 Working of OLED2 OLED Development2.1 Historical Background of OLED2.1.1 International Status2.1.2 National Status3 Progress of Blue Emitters in India4 Present Scenario of Blue OLEDs5 Conclusions and Outlook

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Xu, Ting, Kele Zhao, Haojie Dong, and Lingqiang Meng. "P‐15.1: Optical Modeling Simulation and Experiment of Narrow‐Band Emission Tandem OLEDs, Solution‐Processed Hole Injection/Transport OLEDs and Organic Light Emitting Transistors." SID Symposium Digest of Technical Papers 55, S1 (April 2024): 1420–25. http://dx.doi.org/10.1002/sdtp.17385.

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This study shows the investigations of Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) materials and solution‐processed holes injection/transport layers (HITLs) in organic light‐emitting diodes (OLEDs), while extending to Organic Light Emitting Transistors (OLETs). Firstly, we explore TBN‐TPA, a blue MR‐TADF material, in single‐unit and tandem OLEDs via optical simulation. The tandem architecture enhances color purity, achieving a narrow full width at half maximum down to 24 nm, thus meeting BT 2020 standards. This marks the first instance of tandem OLEDs improving both efficiency and color performance of a multi‐resonance TADF emitter. Concurrently, we investigate the regulation of solution‐processed HITL compositions in OLEDs, aiming to improve charge injection and optical waveguiding. The adoption of solution‐processed HITLs reduces the turn‐on voltage and enhances power efficiency by 8.81% at a brightness of 5000 cd/m2 compared to vacuum‐deposited HITLs. By adjusting the composition of solution‐based PEDOT:PSS/TAPC as HITL, we effectively mitigate hole injection barriers and improve surface morphology, establishing an optical waveguide within the OLED structure. This holistic investigation employs optical simulation to advance high‐performance and cost‐effective OLEDs and OLETs for lighting and displays.

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Berry, Matthew, and Stuart Thomson. "Photoluminescence and Electroluminescence Confocal Imaging of an OLED." ECS Meeting Abstracts MA2024-01, no. 31 (August 9, 2024): 1553. http://dx.doi.org/10.1149/ma2024-01311553mtgabs.

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In recent years organic light-emitting diodes (OLEDs) have become one of the leading technologies for full-colour display panels in high-end smartphones and televisions. This rapid growth in use has occurred because OLEDs offer an all-around superior performance to liquid crystal displays (LCDs). For example, they are thinner, lighter, more flexible, less power consumptive, and brighter. When new OLEDs are developed, the optoelectronic properties of individual components and the complete device can be characterised using photoluminescence (PL) and electroluminescence (EL) spectroscopy. In this poster presentation, we use a confocal Raman microscope to characterise and spatially resolve the optoelectronic properties of a fabricated OLED device with four imaging modalities: PL, EL, time-resolved PL (TRPL), and time-resolved EL (TREL). Using a confocal microscope to characterise an OLED's spectral and time-resolved properties provides much greater detail than bulk measurements. Figure 1

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Sheng, Hao. "Study on Working Principle, Structure, Enhancement Technology, and Applications of Organic Light-emitting Diodes." Highlights in Science, Engineering and Technology 27 (December 27, 2022): 302–10. http://dx.doi.org/10.54097/hset.v27i.3771.

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Nowadays OLEDs outperform normal LEDs in terms of ease-processing, flexibility, skinniness, lightweight, and manufacturing cost. However, there is still much room to improve in terms of materials, efficiency, and longevity. Improving the performance of OLEDs has become the most popular research area. In order to make full use of excitons after recombination of carriers, phosphorescent OLED has been proposed. Recently, there is a gradual trend for phosphorescent OLEDs to be replaced by TADF OLEDs, as these TADF OLEDs can not only exhibit 100% internal quantum efficiency and are cheap to produce because they do not contain precious metals. At the same time, TADF OLEDs are considered to have more room for development especially in the aspect of longevity and color. Therefore, more researches are still needed to solve the blue OLED problem because compared to other colors, such as red and green OLEDs, blue OLEDs still have a big gap in stability and efficiency. In this work, the history of OLEDs, their working principle, the technologies that have been improved, and the cross-border derivative applications were studied.

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Naqvi, Syed, Mirza Baig, Tanveer Farid, Zahid Nazir, Syed Mohsan, Zhe Liu, Wanqing Cai, and Shuai Chang. "Unraveling Degradation Processes and Strategies for Enhancing Reliability in Organic Light-Emitting Diodes." Nanomaterials 13, no. 23 (November 25, 2023): 3020. http://dx.doi.org/10.3390/nano13233020.

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Organic light-emitting diodes (OLEDs) have emerged as a promising technology for various applications owing to their advantages, including low-cost fabrication, flexibility, and compatibility. However, a limited lifetime hinders the practical application of OLEDs in electronic devices. OLEDs are prone to degradation effects during operation, resulting in a decrease in device lifetime and performance. This review article aims to provide an exciting overview of OLED degradation effects, highlighting the various degradation mechanisms. Subsequently, an in-depth exploration of OLEDs degradation mechanisms and failure modes is presented. Internal and external processes of degradation, as well as the reactions and impacts of some compounds on OLED performance, are then elucidated. To overcome degradation challenges, the review emphasizes the importance of utilizing state-of-the-art analytical techniques and the role of these techniques in enhancing the performance and reliability of OLEDs. Furthermore, the review addresses the critical challenges of lifetime and device stability, which are crucial for the commercialization of OLEDs. This study also explores strategies to improve OLEDs’ lifetime and stability, such as using barrier layers and encapsulation techniques. Overall, this article aims to contribute to the advancement of OLED technology and its successful integration into diverse electronic applications.

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Gao, Wei, Jianyun Wang, Yepeng Xiang, Jinghua Niu, Long Chen, and Bong-Geum Lee. "29‐2: Distinguished Paper: High Efficiency and High Color Purity Deep‐Blue Organic Light‐Emitting Diodes with Blue Index >500." SID Symposium Digest of Technical Papers 55, no. 1 (June 2024): 369–72. http://dx.doi.org/10.1002/sdtp.17534.

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Thermally activated delayed fluorescent (TADF) and phosphorescent blue organic light‐emitting diodes (OLEDs) have been developed to overcome the relatively low triplet exciton utilization of traditional fluorescent OLEDs. However, broad emission spectra originating from charge transfer process limits the commercial application of such blue OLEDs. Herein, an effective phosphor‐sensitized fluorescent (PSF) OLED device structure was designed. PSF OLED exhibited a maximum blue index (BI) of 508 cd/A/CIEy with CIEy of 0.060, which has been the highest efficiency result reported for PSF deep‐blue OLEDs. Impressively, the sensitized OLEDs maintained blue index of 407 cd/A/CIEy, narrow emission spectra (FWHM = 17 nm) and high color purity (CIEy = 0.046), revealing the attractive technical advantages and commercial application potential.

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Zhang, Jialin. "Recent research on the status and advances of OLED." Applied and Computational Engineering 25, no. 1 (November 7, 2023): 219–26. http://dx.doi.org/10.54254/2755-2721/25/20230767.

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Organic Light-Emitting Diodes (OLEDs) have already been a prominent display technology in various applications for many decades, ranging from smartphones and televisions to wearable devices and lighting. It is important to understand the current state of OLED research in order to assess its progress, identify challenges, and explore more potential ways for further development. In this paper, the significance and widespread adoption of OLED technology are briefly introduced, and its advantages over traditional display technologies are highlighted. The paper then provides a concise overview of the major components and working principles of OLEDs without delving into basic notions. The paper discusses both small molecule OLEDs (SMOLEDs) and polymer OLEDs (POLEDs), emphasizing their unique structure, characteristics and properties. Different strategies employed to enhance OLED performance is investigated, including the regulation of band gaps that influence the efficiency and brightness. This paper also focuses on the evaluation of device reliability and stability aspects. The techniques and materials employed in studies related to OLED development are also discussed with many searched experimental data and ongoing research activities. Furthermore, the research content covered the aspects of recent commercial advancements in OLED technology, such as Active matrix OLEDs (AMOLED) and Passive matrix (PMOLED). The review provides a guideline for researchers, industry professionals, and enthusiasts to better understand the OLED technology into its details, potential, and the areas that require further exploration.

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Wang, Dongxiang, Jacqueline Hauptmann, and Christian May. "OLED Manufacturing on Flexible Substrates Towards Roll-to-Roll." MRS Advances 4, no. 24 (2019): 1367–75. http://dx.doi.org/10.1557/adv.2019.62.

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ABSTRACTLarge area lighting OLEDs manufactured in a Roll-to-Roll (R2R) fashion enable the well-longed production capability with considerably high throughput based on flexible substrates, hence largely reduced OLED manufacturing cost. This paper will outline the present status of R2R OLED fabrication on ultra-thin glass with the focus on transparent OLED devices and how to perform segmentation by printing of silver- and dielectric pastes. Ultra-thin glass (UTG) is laminated on a PET film to avoid fabrication interruptions when glass cracks occur during the Roll-to-Roll process. The R2R fabricated flexible OLEDs also show key-values comparable to conventional OLEDs fabricated on small rigid glass in lab-scale.

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Zheng, Luping, Jiaju Xu, Yaomiao Feng, Haiquan Shan, Guojia Fang, and Zong-Xiang Xu. "Green solvent processed tetramethyl-substituted aluminum phthalocyanine thin films as anode buffer layers in organic light-emitting diodes." Journal of Materials Chemistry C 6, no. 42 (2018): 11471–78. http://dx.doi.org/10.1039/c8tc00960k.

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Green solvent processable tetramethyl-substituted Al(iii) phthalocyanines were employed as anodic buffer layers of OLEDs, achieving the enhanced OLED performance and durability compared with those of OLEDs using PEDOT:PSS.

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Sahu, Lokesh Kumar, and Vaishali Soni. "OLED: New Generation Display Technology." Journal of Ravishankar University (PART-B) 35, no. 1 (March 8, 2022): 1–8. http://dx.doi.org/10.52228/jrub.2022-35-1-1.

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As time gets advanced multiple progressions have happened in the field of display devices. In this field first came a small LED then after CRT (Cathode Ray Tube) which is used in present days but due to its heaviness, we do not carry it from one place to another. Then after came LCD (Liquid Crystal Display), the problem of bulkiness and required large area overcome by LCD, the only problem with LCD is that it cannot see a clear picture from different angles. LCD is a lightweight and flexible plastic substrate. After all these innovations OLED came and OLED beat all issues of LCD and CRT. OLED is light and slim in design, it does not require any kind of backlight, OLEDs are self-luminous. Polymers are using to fabricate OLEDs or unlike LCDs small molecules in the flat panel zone. It has low power consumption (only 2-10 volts) also OLEDs has a wide viewing angle (up to 160 degrees). The applications of OLEDs in electronics are on the increase on daily basis from camera to cell phones to OLED televisions.

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Adhikary, Apurba, Joy Bhuiya, Saydul Akbar Murad, Md Bipul Hossain, K. M. Aslam Uddin, MD Estihad Faysal, Abidur Rahaman, and Anupam Kumar Bairagi. "Performance evaluation of micro lens arrays: Improvement of light intensity and efficiency of white organic light emitting diodes." PLOS ONE 17, no. 5 (May 27, 2022): e0269134. http://dx.doi.org/10.1371/journal.pone.0269134.

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This paper proposes a unique method to improve light intensity and efficiency of white organic light emitting diodes (OLEDs) by engraving micro lens arrays (MLAs) on the outer face of the substrate layer. The addition of MLAs on the substrate layer improves the light intensity and external quantum efficiency (EQE) of the OLEDs. The basic OLED model achieved an EQE of 14.45% for the effective refractive index (ERI) of 1.86. The spherical and elliptical (planoconvex and planoconcave) MLAs were incorporated on the outer face of the substrate layer to increase the EQE of the OLEDs. The maximum EQE of 17.30% was obtained for Convex-1 (elliptical planoconvex) MLA engraved OLED where the ERI was 1.70. In addition, Convex-1 MLA engraved OLED showed an improvement of 3.8 times on the peak electroluminescence (EL) light intensity compared to basic OLED. Therefore, Convex-1 MLA incorporated OLED can be considered as a potential white OLED because of its excellent light distribution and intensity profile.

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Huang, Yongqi. "Recent research of materials for emissive layer of OLED." Journal of Physics: Conference Series 2608, no. 1 (October 1, 2023): 012012. http://dx.doi.org/10.1088/1742-6596/2608/1/012012.

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Abstract As time has gone on, a lot of changes in display technology have taken place. Organic light-emitting diode (OLED) is the one of the many types of display technology. They have attracted many interests in the academic filed and commercial worlds, and developed rapidly since their earliest introduction. They are now highly regarded and used in the display and lighting industries due to a number of promising characteristics, such as environmentally friendly, high energy efficiency, large area, light weight, and thin shape. Among various light emitting materials, polymers have higher glass transition temperature. Therefore, polymer-based OLEDs exhibit higher stability and have received wide attention. The development of OLED devices can be divided into three main generations of emitter materials based on the technique of the emissive layer of OLEDs. The first generation of OLED is fluorescent OLED (FOLED), the second generation is phosphorescent OLED (POLED), and the third generation is thermally activated delayed fluorescence (TAFD). In this article, device structure, mechanism and development of polymer-based OLEDs are introduced. Specifically, working principles and materials of the three generations are presented with a focus on TADF-based OLEDs. In addition, their device performances including quantum efficiency and lifetime are compared quantitatively.

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Li, Tsai Cheng, Rwei Ching Chang, and Yan Jun Chen. "Improving the Performance of Organic Light Emitting Diodes by Doping PEDOT:PSS." Advanced Materials Research 881-883 (January 2014): 1130–35. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1130.

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Organic light emitting diodes (OLEDs) have the potential to compete with other rivals in applications of lighting and small size displays because of low power consumption. To achieve commercial standard, however, the luminance efficiency and device lifetime of the OLEDs still need to be improved. This work characterizes the performance of OLEDs improved by Poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT:PSS). PEDOT:PSS films are deposited on ITO glass by spin coating at the first, and then the hole transporting layer and electron transporting layer of the OLED materials N, N '-bis (naphthalene-1-yl)-N, N '-bis (phenyl) benzidine/tris-(8-hydroxyquinoline) aluminum (NPB/Alq3) are thermally evaporated with 1 Å/s deposition rate. The thickness effects of the PEDOT:PSS on the OLED performance are studied. The result shows that PEDOT:PSS effectively improves the luminance of the OLEDs, where 40 nm thick PEDOT:PSS increases 12% and 30 nm thick increases 31% luminance, respectively. Furthermore, the effects of the PEDOT:PSS on the mechanical properties of the OLED are also studied.

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Kondakov, Denis Y. "Triplet–triplet annihilation in highly efficient fluorescent organic light-emitting diodes: current state and future outlook." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2044 (June 28, 2015): 20140321. http://dx.doi.org/10.1098/rsta.2014.0321.

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Studies of delayed electroluminescence in highly efficient fluorescent organic light-emitting diodes (OLEDs) of many dissimilar architectures indicate that the triplet–triplet annihilation (TTA) significantly increases yield of excited singlet states—emitting molecules in this type of device thereby contributes substantially to their efficiency. Towards the end of the 2000s, the essential role of TTA in realizing highly efficient fluorescent devices was widely recognized. Analysis of a diverse set of fluorescent OLEDs shows that high efficiencies are often cor-related to TTA extents. It is therefore likely that it is the long-term empirical optimization of OLED efficiencies that has resulted in fortuitous emergence of TTA as a large and ubiquitous contributor to efficiency. TTA contributions as high as 20–30% are common in the state-of-the-art OLEDs, and even become dominant in special cases, where TTA is shown to substantially exceed the spin-statistical limit. The fundamental features of OLED efficiency enhancement via TTA—molecular structure-dependent contributions, current density-dependent intensities in practical devices and frequently observed antagonistic relationships between TTA extent and OLED lifetime—came to be understood over the course of the next few years. More recently, however, there was much less reported progress with respect to all-important quantitative details of the TTA mechanism. It should be emphasized that, to this day and despite the decades of work on improving blue phosphorescent OLEDs as well as the recent advent of thermally activated delayed fluorescence OLEDs, the majority of practical blue OLEDs still rely on TTA. Considering such practical importance of fluorescent blue OLEDs, the design of blue OLED-compatible materials capable of substantially exceeding the spin-statistical limit in TTA, elimination of the antagonistic relationship between TTA-related efficiency gains and lifetime losses, and designing devices with an extended range of current densities producing near-maximum TTA electroluminescence are the areas where future improvements would be most beneficial.

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Zhang, Jiaming, Yuanhe Wang, Shihao Liu, Hongwei Yu, Letian Zhang, and Wenfa Xie. "Color-tunable organic light-emitting diodes with ultrathin thermal activation delayed fluorescence emitting layer." Applied Physics Letters 120, no. 17 (April 25, 2022): 171102. http://dx.doi.org/10.1063/5.0084137.

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Recently, organic light-emitting diodes (OLEDs) are becoming increasingly attractive to information security, wearable healthcare, and other fields. These fields propose different requirements for performances of OLEDs, especially for voltage-controlled color tunability. In this study, it is proposed to use an ultrathin layer consisting of thermally activated delayed fluorescence (TADF) material as an emitting layer of OLEDs. On the one hand, compared to devices with an ultrathin phosphorescent emitting layer, the OLEDs with TADF show observable color-tunability. On the other hand, the color-tunable OLEDs with TADF show much higher efficiency than the color-tunable fluorescent OLEDs. It demonstrates that the reverse intersystem crossing process not only enhances the exciton utilization efficiency but also leads to an insufficient host-guest energy transfer. With this strategy, a color-tunable OLED is achieved with an external quantum efficiency about 8% and shows color variations over (0.04, 0.08) when its bias voltage increases from 4 to 8 V. By combining with a patterned mask technique, the color-tunable OLEDs can potentially be applied to the field of anti-counterfeiting and status lighting.

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Lee, Jaesang. "65‐1: Invited Paper: Diverse Effects of Defects on the Performance of Organic Light‐Emitting Diodes." SID Symposium Digest of Technical Papers 54, no. 1 (June 2023): 927–28. http://dx.doi.org/10.1002/sdtp.16717.

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Defects in organic light‐emitting diodes (OLEDs) generate the electronic states whose energy level are usually found in the energy gap of OLED materials. Hence, defects can disturb the movement of, and sometimes eliminate, the charges and excitons in OLEDs. Here, we discuss how the properties of the defects, i.e., their originating positions, energy levels and densities, affect the dynamics of the charges and excitons, thereby determining the electrical and optical performance of the comprising OLEDs.

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Cheng, Zhendong, and Zimeng Yan. "The Introduction of Different Types of OLEDs." Applied and Computational Engineering 3, no. 1 (May 25, 2023): 362–67. http://dx.doi.org/10.54254/2755-2721/3/20230552.

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As display technology advances, organic light emitting diodes (OLEDs) have attracted a lot of attention worldwide due to their light weight, flexibility, wide viewing angle, etc. This paper briefly introduces the history and the different historical OLEDs, including phosphorescence, thermally activated delayed fluorescence (TADF), and triplet-triplet annihilation (TTA). Then, this article mainly presents two kinds of OLEDs. The first is small-molecule OLED with typical three organic layers. The purity of the material is quite high, and it can produce high-quality films with high fluorescence quantum efficiency, which can produce a variety of colors of light. Its disadvantages are poor thermal stability and limited carrier transport capacity. The second is polymer based OLED. Compared with small molecule organic luminescence materials, polymer materials have higher physical strength, better processibility, mechanical properties, and thermal stability. In this regard, recent research progress and the comparison between these two types of OLEDs are proposed. They both are considered the most promising display technologies.

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Xue, Yan, Qiong Nie, Xin Hou, Baolei Wang, Yanbo Chen, Yu Zhang, and Lijuan Xiang. "Deep-Blue Organic Light-Emitting Diodes Employed Traditional Hole Transporting Material as Emitter for 31-Inch 4K Flexible Display." Crystals 13, no. 4 (April 17, 2023): 687. http://dx.doi.org/10.3390/cryst13040687.

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High-efficiency deep-blue organic light-emitting diodes (OLEDs) play a crucial role in realizing ultra-high-definition (UHD) flat-panel displays and reducing power consumption. Generally, most reported OLEDs with a Commission Internationale de L’Eclairage (CIE) y coordinate < 0.06 are achieved by traditional fluorescent deep-blue emitters. However, it is challenging to obtain deep-blue fluorescent OLEDs with a high external quantum efficiency (EQE) (reaching the theoretical limit of 5%). In this work, we have successfully employed a hole-transporting material for an emitter, which can increase the efficiency in deep-blue OLEDs. The device employed with the proposed hole-transporting material exhibits deep-blue emission peaks at 427.0 nm with CIE coordinates of (0.155, 0.051), a turn-on voltage (Von) of 4.5 V, and an EQE of 4.5%. The performance of the OLED can be improved by 5.0% by optimizing the device structure. Finally, the flexible display when using the OLED devices exhibited a high image quality.

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Lim, Seongmin, Hyeon-Sik Ahn, Eun-Jeong Jang, So-Young Boo, Akpeko Gasonoo, Jin-Seog Gwag, Jae-Hyun Lee, and Yoonseuk Choi. "Polymer Dispersed Liquid Crystal Imprinted by Microlens Array for Enhanced Outcoupling Efficiency of Organic Light Emitting Diode." Molecules 29, no. 1 (December 22, 2023): 73. http://dx.doi.org/10.3390/molecules29010073.

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In this paper, we demonstrate the use of polymer dispersed liquid crystal (PDLC) imprinted with a microlens array (MLA) via solution process to improve the outcoupling efficiency of organic light emitting diodes (OLEDs). The PDLC, well known for its scattering effect, is an excellent technology for improving the outcoupling efficiency of OLEDs. Additionally, we introduce a simple spin-coating process to fabricate PDLC which is adaptable for future solution-processed OLEDs. The MLA-imprinted PDLC applied OLED shows an enhancement factor of 1.22 in outcoupling efficiency which is a 37.5% increase compared to the existing PDLC techniques without changing the electrical properties of the OLED. Through this approach, we can expect the roll-to-roll based extremely flexible OLED, and with further research on pattering PDLC by various templates, higher outcoupling efficiency is achievable through a simple UV irradiation process.

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Liu, Kang Ping, Min Yu Chen, Yi Zhao, Sai Hu Pan, Cui Yun Peng, Wei Xia Lan, and Bin Wei. "Low Energy-Consumption Inverted Orange Organic Light-Emitting Diodes with Reduced Efficiency Roll-Off." Materials Science Forum 976 (January 2020): 104–9. http://dx.doi.org/10.4028/www.scientific.net/msf.976.104.

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Inverted organic light-emitting diodes (IOLEDs) have a bottom cathode, making them convenient to integrate with the preferred n-type active matrix OLED driving technologies. Furthermore, inverted OLEDs show much better air-stability compared with conventional OLEDs, due to the very reactive and sensitive of alkali doped electron injection layer (EIL) towards ambient oxygen and moisture. For inverted OLEDs, the bottleneck to limit their efficiency and stability is the interface at cathode/EIL and light emitting layer (EML)/charge transporting layer. In this paper, we have investigated the effect of different electron/hole transporting layers on the turn-on voltage, efficiency roll-off and power consumption of inverted orange OLEDs. We found that the device exhibits extremely-low efficiency roll-off and a significant lifetime improvement.

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Sachnik, Oskar, Xiao Tan, Paul W. M. Blom, and Gert-Jan A. H. Wetzelaer. "37‐1: Invited Paper: Efficient Single‐layer Blue‐emitting OLEDs." SID Symposium Digest of Technical Papers 55, no. 1 (June 2024): 475–77. http://dx.doi.org/10.1002/sdtp.17562.

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For single‐layer OLEDs to achieve efficiencies approaching those of multilayer devices, balanced charge transport is a prerequisite. We demonstrate a single‐layer blue‐emitting OLED with unity internal quantum efficiency and an external quantum efficiency of 27.7% with minor roll‐off at high brightness. These findings lay the foundations for efficient solution‐processed OLEDs.

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Lim, Dogi, Jun-Young Park, Seungwon Lee, Jian Cheng Bi, Seonghyeon Park, Junbeom Song, Ji-Sung Lee, Hyejung Lim, and Byeong-Kwon Ju. "P‐254: Late‐News Poster: Design Optimization and Considering Mass Production of 2D Hole Arrayed Double Anode Structure for Improving Outcoupling Efficiency of OLEDoS." SID Symposium Digest of Technical Papers 55, no. 1 (June 2024): 2222–25. http://dx.doi.org/10.1002/sdtp.18054.

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AR, VR Headset for “metaverse” is one of candidates to widen human life experiences with virtual reality. Display requirement for headset is the high resolution as to 3000ppi that needs to enhance outcoupling efficiency of OLED (OLEDoS). We optimized 2D hole arrayed double anode structure for mass production with materials, thickness of anode and interlayer, process variation of etching top anode, and particles in double anodes. Outcoupling efficiency of optimized structure is improved to 1.377 folds than conventional TE‐OLEDs. We hope that this study promotes more approaches to excite SPPs of anode.

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Daris Alfafa, Daniel Moraru, and Arief Udhiarto. "A Fabrication of Organic Light Emitting Diodes (OLEDs) using the Lamination method in a Vacuum-Free Environment." International Journal of Electrical, Computer, and Biomedical Engineering 1, no. 2 (December 30, 2023): 54–64. http://dx.doi.org/10.62146/ijecbe.v1i2.24.

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Organic Light Emitting Diodes (OLEDs) have recently become one of the fastest-growing technologies in the world. The challenge in OLED fabrication, especially larger-area OLEDs, is its relatively high costs and complexity. The lamination method at a vacuum-free environment is an approach to simplify and reduce the cost of fabrication. This paper reports our latest progress on OLEDs fabricated using the said method and condition. The processing parameters were explored and optimized. Spin coating the emissive Layer (PFO) at 1300 rpm and the anode (TC-07-S) at 3000 rpm yield the best results in terms of current conduction and success rate. Laminating the OLEDs at 160 °C, with 245 N of force, and for 30 seconds, gave the best results in terms of previously stated parameters. Furthermore, the constituting materials of the OLEDs were explored. It was found that TC-07-S as an anode, PFO as the light-emitting material, a 30-micrometer thick aluminum foil as the cathode, and Kapton as the dielectric and adhesive material yielded the best results. These results may pave the way for other innovative methods to fabricate OLEDs with a simple and affordable processes.

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Ahsan, Md Shamim, Md Arif Istiaq Arafat, Tasmima Akter, Ik Bu Sohn, and Hun Kook Choi. "Light Extraction Efficiency Enhancement of White Organic Light-Emitting Diodes (OLEDs) by Micro/Nano-Patterning the Substrate Layer." Defect and Diffusion Forum 432 (March 25, 2024): 85–106. http://dx.doi.org/10.4028/p-bx2ouv.

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We demonstrate the enhancement of light extraction efficiency of surface-emitting white Organic Light Emitting Diodes (OLEDs) by incorporating micro/nano-metric structures on the outer surface of the 3-layer substrate (SiO2-Si3N4-SiO2). To enhance light extraction efficiency of the OLEDs, various light scattering structures including plano-convex & plano-concave micro-lens array, flat-top & round-top nano-pillars array, and wavy structures were engraved on the outer surface of the substrate layer. For optimization, we varied the thickness of the internal layers of the OLEDs, and height, width, period, and radius of the micro/nano-scale structures. The performance of the micro/nano-structured OLEDs was simulated and analyzed using Lumerical FDTD and GPVDM simulators. We examined the far field light intensity, transmitted power, angular distribution of light, photon escape probability, photon density, internal & external quantum efficiency, and current-voltage curve of the designed OLEDs. We investigated the results in different locations, especially after the substrate layer: Far Field-1 (0 μm), and Far Field-2 (2.5 μm). Compared to conventional OLEDs, the micro/nano-structured OLEDs showed higher external quantum efficiency. The highest external quantum efficiency of 67.304% (Far Field-1) was detected in the round-top nano-pillars array engraved white OLED having structure period of 1.2 μm. We strongly believe that, the proposed micro/nano-structured white OLEDs are suitable for lighting applications.

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Chandra, V. K., B. P. Chandra, and Piyush Jha. "Organic Light - Emitting Diodes and their Applications." Defect and Diffusion Forum 357 (July 2014): 29–93. http://dx.doi.org/10.4028/www.scientific.net/ddf.357.29.

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Organic light emitting diodes (OLEDs) have been the focus of intense study since the late 1980s, when the low voltage organic electroluminescence in small organic molecules such as Alq3, and large organic molecules such as polymers (PPV), was reported. Since that time, research has continued to demonstrate the potential of OLEDs as viable systems for displays and eco-friendly lighting applications. OLEDs offer full colour display, reduced manufacturing cost, larger viewing angle, more flexible, lower power consumption, better contrast, slimmer, etc. which help in replacing the other technologies such as LCD. The operation of OLEDs involves injection of charge carriers into organic semiconducting layers, recombination of charge carriers, formation of singlet and triplet excitons, and emission of light during decay of excitons. The maximum internal quantum efficiency of fluorescent OLEDs consisting of the emissive layer of fluorescent organic material is 25% because in this case only the 25% singlet excitons can emit light. The maximum internal quantum efficiency of phosphorescent OLEDs consisting of the emissive layer of fluorescent organic material mixed with phosphorescent material of heavy metal complexes such as platinum complexes, iridium complexes, etc. is nearly 100% because in this case both the 25% singlet excitons and 75% triplet excitons emit light. Recently, a new class of OLEDs based on thermally activated delayed fluorescence (TADF) has been reported, in which the energy gap between the singlet and triplet excited states is minimized by design, thereby promoting highly efficient spin up-conversion from non-radiative triplet states to radiative singlet states while maintaining high radiative decay rates of more than 106decays per second. These molecules harness both singlet and triplet excitons for light emission through fluorescence decay channels and provides an intrinsic fluorescence efficiency in excess of 90 per cent and a very high external electroluminescence efficiency of more than 19 per cent, which is comparable to that achieved in high-efficiency phosphorescence-based OLEDs.The OLED technology can be used to make screens large enough for laptop, cell phones, desktop computers, televisions, etc. OLED materials could someday be applied to plastic and other materials to create wall-size video panels, roll-up screens for laptops, automotive displays, and even head wearable displays. Presently, the OLEDs are opening up completely new design possibilities for lighting in the world of tomorrow whereby the offices and living rooms could be illuminated by lighting panels on the ceiling. The present paper describes the salient features of OLEDs and discusses the applications of OLEDs in displays and solid state lighting devices. Finally, the challenges in the field of OLEDs are explored. Contents of Paper

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Choi, Geun Su, Eun Jeong Bae, Byeong-Kwon Ju, and Young Wook Park. "P‐207: Enhancing OLED Optical Characteristics through Simple Fabrication of High Aspect Ratio Nanostructures based on photosensitive photopolymer for External Light Extraction." SID Symposium Digest of Technical Papers 55, no. 1 (June 2024): 2170–72. http://dx.doi.org/10.1002/sdtp.18038.

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Investigated nano‐pillar‐based light extraction methods for OLEDs. Explored photosensitive photopolymer (SU‐8) based random nanostructure's impact on light extraction efficiency. Achieved 85% visible spectrum transmittance, highest efficiency with minimal unetched structure thickness. Compared to OLEDs lacking nano‐pillar structure, saw up to 38% improved quantum efficiency and 40% enhanced power efficiency. Insights aid in optimizing these structures for OLED advancement.

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LI, Yilian, Na LIU, Pengchao ZHOU, Weixia LAN, Huayan PU, and Yingjie LIAO. "Efficient and Color-tunable Organic Light-emitting Diodes for Rear Light Application on the Motor Vehicle." Materials Science 27, no. 3 (August 23, 2021): 264–68. http://dx.doi.org/10.5755/j02.ms.24678.

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By designing double emissive layers, orange light-emitting layer (EML) and red EML and a space layer of blending hole-transporting material (HTM) with electron-transporting material (ETM), we have achieved efficient and color-tunable organic light-emitting diodes (OLEDs). It is found that the red shift of EL spectrum was enhanced when the ratio of HTM to ETM was 5:1. And a maximum current efficiency of 41.17 cd/A was reached. It has been demonstrated that two ultra-thin emissive layers could improve the current efficiency of the OLEDs. The current efficiency of the OLEDs with a 1 nm o;6range EML and a 1 nm red EML was enhanced by 27.4 % as compared to the reference devices. This is a novel approach to realizing voltage-controlled electroluminescence (EL) over different colors and intensity in a single OLED. The color-tunable OLEDs show the potential to be utilized as rear light on motor vehicle. We have investigated the effect of the ratio of HTM to ETM on the efficiency and spectral shift of the OLEDs through the control of recommendation zone.

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Mischok, Andreas, Sabina Hillebrandt, Seonil Kwon, and Malte C. Gather. "61‐1: Invited Paper: Polaritonic OLEDs with Assistant Strong‐coupling Layers: A New Approach to Sub‐20nm Emission Linewidth in OLED Displays." SID Symposium Digest of Technical Papers 55, no. 1 (June 2024): 835–37. http://dx.doi.org/10.1002/sdtp.17660.

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With ever more stringent color‐gamut requirements in displays (e.g., BT.2100), there is growing demand for OLEDs with narrowband emission. However, many efficient emitters reported to date show spectrally broad luminescence. Micro‐cavity OLEDs offer narrow linewidth but suffer from changes in spectrum with observation angle. To overcome these limitations, we hybridize microcavity and exciton states in an efficient OLED, thus creating strongly coupled polariton states that inherit the angle insensitivity of excitons and the narrow linewidth of the microcavity. Using assistant strong‐coupling layers located away from the recombination zone yields efficient OLEDs with FWHM <20 nm and angle shift <10 nm @60° tilt.

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Blankenbach, Karlheinz. "46.1: Invited Paper: LCD Innovations vs. OLED Performance for Automotive Applications." SID Symposium Digest of Technical Papers 54, S1 (April 2023): 327–30. http://dx.doi.org/10.1002/sdtp.16295.

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LCDs are today's workhorse for automotive displays. In recent years, some premium OEMs started to ship cars with OLED displays. The advantages of OLEDs compared to LCDs are short response time at low temperature (relevant for e‐mirrors) and perfect black at night as well as highly curved and transparent versions. Replacing edge‐lit backlight of LCDs by FALD (full array local dimming) results in highest luminance at acceptable halo. Furthermore, LCDs have a large supply chain, which results in competitive cost. Well‐known challenges of OLEDs deal with high luminance and temperature sensitivity, which can result in reduced lifetime (LT) incl. Burn‐In. Challenges and solutions for LCDs and OLEDs such as halo measurements and viewing angle performance will be discussed more in detail. Latest automotive demonstrators show the potential of micro‐LEDs and electrically pumped Quantum Dots (QD) displays. Both have the potential to outperform LCDs and OLEDs.

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Xing, Xiaolin, Ziye Wu, Yingying Sun, Yunlong Liu, Xiaochen Dong, Shuhong Li, and Wenjun Wang. "The Optimization of Hole Injection Layer in Organic Light-Emitting Diodes." Nanomaterials 14, no. 2 (January 11, 2024): 161. http://dx.doi.org/10.3390/nano14020161.

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Organic light-emitting diodes (OLEDs) are widely recognized as the forefront technology for displays and lighting technology. Now, the global OLED market is nearly mature, driven by the rising demand for superior displays in smartphones. In recent years, numerous strategies have been introduced and demonstrated to optimize the hole injection layer to further enhance the efficiency of OLEDs. In this paper, different methods of optimizing the hole injection layer were elucidated, including using a suitable hole injection material to minimize the hole injection barrier and match the energy level with the emission layer, exploring new preparation methods to optimize the structure of hole injection layer, and so on. Meanwhile, this article can help people to understand the current research progress and the challenges still faced in relation to the hole injection layer in OLEDs, providing future research directions to enhance the properties of OLEDs.

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Hande, Savithri, and Prajna K B. "Survey on Organic Light Emitting Diode." International Journal of Innovative Science and Research Technology 5, no. 6 (July 2, 2020): 630–36. http://dx.doi.org/10.38124/ijisrt20jun492.

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Organic light emitting diodes is a new display technology, which uses organic thin materials that are placed between conductors. When an electric current is applied, a bright light is emitted. OLEDs are thin, transparent, flexible, foldable displays. In 1987 researchers of Eastman Kodak company invented OLED diode technology. The principal inventors were Chemists Ching W. Tang and Steven Van Slyke. In 2001 they received an Industrial Innovation Award from the American Chemical Society for their contribution in organic light emitting diodes. In 2003, Kodak realised its first OLED display had 512 by 218 pixels, 2.2 inch. Two technologies necessary to make flexible OLEDs were invented by Researchers at Pacific Northwest National Laboratory and the Department of Energy. Many researchers are contributing to improve the OLED technology. In this paper we give a brief of what is OLED, types of OLED, different fabrication methods of OLED, advantages and disadvantages of OLED.

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Lee, Seok Je, Jun Li, Seung Il Lee, Chang-Bum Moon, Woo Young Kim, Jin Cao, and Chul Gyu Jhun. "Effects of MEH-PPV Molecular Ordering in the Emitting Layer on the Luminescence Efficiency of Organic Light-Emitting Diodes." Molecules 26, no. 9 (April 25, 2021): 2512. http://dx.doi.org/10.3390/molecules26092512.

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We investigated the effects of molecular ordering on the electro-optical characteristics of organic light-emitting diodes (OLEDs) with an emission layer (EML) of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). The EML was fabricated by a solution process which can make molecules ordered. The performance of the OLED devices with the molecular ordering method was compared to that obtained through fabrication by a conventional spin coating method. The turn-on voltage and the luminance of the conventional OLEDs were 5 V and 34.75 cd/m2, whereas those of the proposed OLEDs were 4.5 V and 120.3 cd/m2, respectively. The underlying mechanism of the higher efficiency with ordered molecules was observed by analyzing the properties of the EML layer using AFM, SE, XRD, and an LCR meter. We confirmed that the electrical properties of the organic thin film can be improved by controlling the molecular ordering of the EML, which plays an important role in the electrical characteristics of the OLED.

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Zhong, Gao Yu, Pei Yuan Fang, and Yong Ming Cao. "Organic Light-Emitting Diodes with Varying Thickness of Bathocuproine Layer." Materials Science Forum 694 (July 2011): 901–7. http://dx.doi.org/10.4028/www.scientific.net/msf.694.901.

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A series of organic light-emitting diodes (OLEDs) with or without a bathocuproine (BCP) layer inserted in the control device indium-tin-oxide (ITO)\ N,N'-bis-(1-naphthl)-diphenyl-1,1'- biphenyl-4,4'-diamine (NPB)\ tris(8-quinolinolato) aluminum (Alq)\LiF\Al have been fabricated and measured. Different influences of the BCP layer on electroluminescence (EL) of the OLEDs have been investigated. It is found that the highest efficiency of the OLED with a 1-nm BCP layer inserted between NPB and Alq increases to 3.99 cd/A, ~48% higher than that of the control device, while the EL efficiencies of the devices with other structures are similar to the latter. This phenomenon is ascribed to the hole-blocking effect of the BCP layer and the resulting higher density of carriers in the emission zone of the OLED. The EL performances of the OLEDs with different thicknesses of BCP layer are also discussed in details.

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Cho, Jung Yohn, and Ho Jung Chang. "Preparation and Characterization of Organic Light Emitting Devices Using QD Dopant." Materials Science Forum 449-452 (March 2004): 1021–24. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.1021.

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Two types of the organic light-emitting devices (OLEDs) with different emission structures were prepared using Alq3 (aluminum tris 8-hydroxyquinoline) host material and quinacridone (QD) dopant at the emission layer. One is the OLED device with emission layer consisting of Alq3 host material doped with QD dopant ("codoped OLED"). The another one has a seperated QD dopant film in the Alq3 emission layer ("undoped OLED"). The maximum brightness of the codoped and undoped OLEDs were 3207 cd/m2 and 1570 cd/m2, respectively. The wavelength of the maximum emission peak in the undoped sample was 527 nm and shifted slightly toward longer wavelength with the value of 540 nm for the codoped OLED sample. The maximum luminous efficiency of the undoped OLED was about 1.4 lm/W and increased to 7.0 lm/W for the codoped sample.

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Momodu, D. Y., T. Tong, M. G. Zebaze Kana, and W. O. Soboyejo. "Adhesion and Degradation of Organic and Hybrid Organic-Inorganic Light-Emitting Devices." Advanced Materials Research 1132 (December 2015): 185–203. http://dx.doi.org/10.4028/www.scientific.net/amr.1132.185.

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This paper presents the results of a combined analytical, computational and experimental study of adhesion and degradation of Organic Light Emitting Devices (OLEDs). The adhesion between layers that are relevant to OLEDs is studied using force microscopy during Atomic Force Microscopy. The interfacial failure mechanisms associated with blister formation in OLEDs and the addition of TiO2nanoparticles (into active regions) are then elucidated using a combination of fracture mechanics/finite element modeling and experiments. The blisters observed in the models are shown to be consistent with the results from adhesion and interfacial fracture mechanics models. The implications of the work are discussed for the future design of OLED structures with improved lifetimes and robustness.

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Yadav, Rohit Ashok Kumar, Mangey Ram Nagar, Deepak Kumar Dubey, Sujith Sudheendran Swayamprabha, and Jwo-Huei Jou. "Highly-Efficient Solution-Processed Organic Light Emitting Diodes with Blend V2O5-PEDOT:PSS Hole-Injection/Hole-Transport Layer." MRS Advances 4, no. 31-32 (2019): 1779–86. http://dx.doi.org/10.1557/adv.2019.261.

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ABSTRACTOrganic light-emitting diodes (OLEDs) have attracted huge concern because of their intrinsic characteristics and ability to reach the pinnacle in the field of high-quality flat-panel displays and energy-efficient solid-state lighting. High-efficiency is always a key crux for OLED devices being energy-saving and longer life-span. OLEDs have encountered enormous difficulties in meeting the requirements for large-sized devices due to a major limitation in vacuum thermal evaporation technology. In multilayered OLED devices, the characteristics of the charge injection/transport layer is a crucial factor for the operating-voltage, power-efficiency and stability of the device. Transition metal oxides have shown great potential owing to their wide range of possible energy level alignments, balanced charge injection, and improvement of carrier mobilities. In this study, we report a solution-processed blend V2O5-PEDOT:PSS hole-injection/hole-transport layer (HIL/HTL) for efficient orange phosphorescent OLEDs. The electroluminescent characteristics of blend V2O5-PEDOT:PSS based devices were studied with the structure ITO/V2O5-PEDOT:PSS/CBP:Ir(2-phq)3/TPBi/LiF/Al. The V2O5-PEDOT:PSS based OLEDs displayed relatively higher device performance and low roll-off than that of the counter PEDOT:PSS device in terms of a maximum luminance of 17,670 cd m-2, power efficiency of 19.4 lm W-1, external quantum efficiency of 8.7%, and more importantly, low turn-on voltage. These results demonstrate an alternative approach based on metal oxide/organic blend HIL/HTL as a substitute of PEDOT:PSS for high-efficiency solution process OLEDs.

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Izawa, Seiichiro. "(Invited) Blue Organic Light-Emitting Diode Using Dynamic Exciton for Low Driving Voltage." ECS Meeting Abstracts MA2024-01, no. 13 (August 9, 2024): 1039. http://dx.doi.org/10.1149/ma2024-01131039mtgabs.

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Among the three primary colors, blue emission in organic light-emitting diodes (OLEDs) are highly important but very difficult to develop. OLEDs have already been commercialized; however, blue OLEDs have the problem of requiring a high applied voltage due to the high-energy of blue emission. Herein, an ultralow voltage turn-on at 1.47 V for blue emission with a peak wavelength at 462 nm (2.68 eV) is demonstrated in an OLED device. This OLED reaches 100 cd/m2, which is equivalent to the luminance of a typical commercial display, at 1.97 V. Blue emission from the OLED is achieved by the selective excitation of the low-energy triplet states at a low applied voltage by using the charge transfer (CT) state as a precursor and the triplet-triplet annihilation, which forms one emissive singlet from two triplet excitons. We found that the essential component for efficient blue emission is a smaller energy difference between the CT state and triplet exciton, accelerating the energy transfer between the two states and achieving the optimal performance by avoiding direct decay from the CT state to the ground state. Our study demonstrates that the developed OLED allows for a much longer operation lifetime than that from a typical blue phosphorescent OLED because the blue emission originates from a stable low-energy triplet exciton that avoids degrading the constituent materials.

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Nan, Ji, Yupei Zhang, Zhi Huang, Long Chen, and Bong‐Geum Lee. "21‐2: Modulus Spectroscopy and Capacitance‐Voltage Measurement of OLEDs as Tools for Estimating Charge Dynamics." SID Symposium Digest of Technical Papers 55, no. 1 (June 2024): 260–63. http://dx.doi.org/10.1002/sdtp.17504.

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In the past few decades, the injection and transporting characteristics of charge carriers in organic light emitting diodes (OLEDs) have been analyzed using hole‐only and electron‐only devices (HODs and EODs). However, such methods cannot fully explain the dynamic characteristics of OLEDs such as charge accumulation and recombination. In this study, we well‐established the combination of modulus spectroscopy and capacitance‐voltage measurement and applied it to describe the carrier dynamics in OLED devices.

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Jeong, Changyeong, Yong-Bum Park, and L. Jay Guo. "Tackling light trapping in organic light-emitting diodes by complete elimination of waveguide modes." Science Advances 7, no. 26 (June 2021): eabg0355. http://dx.doi.org/10.1126/sciadv.abg0355.

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Conventional waveguide mode decoupling methods for organic light-emitting diodes (OLEDs) are typically not scalable and increase fabrication complexity/cost. Indium-tin-oxide–free transparent anode technologies showed efficiency improvement without affecting other device properties. However, previous works lack rigorous analysis to understand the efficiency improvement. Here, we introduced an ultrathin silver (Ag) film as transparent electrode and conducted systematic modal analysis of OLEDs and report that waveguide mode can be completely eliminated by designing an OLED structure that is below the cutoff thickness of waveguide modes. We also experimentally verified the waveguide mode removal in organic waveguides with the help of index-matching fluid and prism. The negative permittivity, extremely thin thickness (~5 nanometers), and highly conductive properties achieved by a uniform copper-seeded Ag film can suppress waveguide mode formation, enhancing external quantum efficiency without compromising any other characteristics of OLEDs, which paves the way for cost-effective high-efficiency OLEDs in current display industry.

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Han, Chul Hee. "A Study of Photo and Photocatalytic Degradation of Arylamine with Respect to Design of Organic Light-Emitting Diode." Materials Science Forum 695 (July 2011): 194–97. http://dx.doi.org/10.4028/www.scientific.net/msf.695.194.

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In our study of organic molecules for OLED, we have paid attention to 4,4'-bis(N-carbazolyl)biphenyl (CBP), an arylamine commonly used as phosphorescent host or hole transport material in OLED, and performed photochemical and photocatalytic experiments. For the photocatalytic experiment, heterogeneous mixture of CBP and TiO2powder (Degussa P25) in tetrahydrofuran solution has been placed under UV radiation. Both photochemical and photocatalytic experiments have resulted in degradation of CBP, however, with widely different rates and degradation products. With ever increasing demand for high performance OLEDs, higher stability and longer lifetime of their organic components are essential. In this respect, current informations are sure to be valuable in the design and operation of OLEDs as well as arylamine-based OLED.

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Choi, Geun Su, Dong-Hyun Baek, and Young Wook Park. "Organic Thin-Film Characteristics Modulated by Deposition Substrate Rotation Speed and the Effect on Organic Light-Emitting Diodes." Journal of Nanoscience and Nanotechnology 21, no. 8 (August 1, 2021): 4185–91. http://dx.doi.org/10.1166/jnn.2021.19383.

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In this paper, we report on the effects of the substrate thermal evaporation process rotation speed on the electroluminescence (EL) characteristics of organic light-emitting diodes (OLEDs). In general OLED research, rotational and angle tilted deposition are widely used to maintain uniformity. However, there have been few reports on the effects of this deposition method on film characteristics. We analyzed these effects and found that the film density and its refractive index showed remarkable changes as a function of substrate rotational speed during tilted deposition. The EL characteristics of the transport layer of fluorescent OLEDs were also significantly affected. We derived the OLED optimal thickness and refractive index from our calculations.

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Park, Chan Young, Chang-Ho Hyun, and Byoungdeog Choi. "P‐124: Efficiency Enhanced Top Emitting OLED‐on‐Silicon Microdisplay with Aluminum Anode." SID Symposium Digest of Technical Papers 54, no. 1 (June 2023): 1314–16. http://dx.doi.org/10.1002/sdtp.16823.

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A top emitting organic light emitting diode‐on‐silicon (OLEDoS) panel with aluminum (Al) anode for high‐resolution microdisplays was proposed and fabricated. The low work function of the Al anode increases the energy barrier of the interface between the anode and hole injection layer (HIL), and has poor hole‐injection properties, which causes the low efficiency of the device. To enhance the hole‐injection characteristics of the Al anode, we applied optimized HIL and hole transportation layer (HTL) materials. The proposed single stack structure white OLED display panel with Al anode was fabricated on CMOS backplane and the white OLED device improved efficiency by up to 20 cd/A at 1000 nit, which is 90% of the level of conventional OLEDs with indium tin oxide (ITO) anode.

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Janietz, Silvia, Björn Gruber, Sylvia Schattauer, and Kerstin Schulze. "Integration of OLEDs in Textiles." Advances in Science and Technology 80 (September 2012): 14–21. http://dx.doi.org/10.4028/www.scientific.net/ast.80.14.

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In place of silicon, which is normally used in microelectronics, organic materials offer the opportunity to produce devices on large area, low-cost and plastic planar substrates. These materials are attracting increased attention also in the field of electronic-textiles (e-textiles) because they show an interesting combination of electronic and mechanical properties that can be favourably exploited in smart textiles. A key step for the integration of mass production of e-textiles is to combine electronic production with textile manufactures. In the last years, progress has been achieved in the development of fibers and their processing for application in e-textiles. The application ranged from fabric integrated light sources to low cost solid state lighting for protection and security. Here research results are presented regarding the integration of encapsulated glass OLEDs and additionally OLEDs fabricated on flexible high barrier substrates which were integrated into textiles. On the other hand, the first results concerning the realization of an OLED on cylindrical surfaces based on solution processed technologies which is a first step in the direction of low cost processing will be discussed. A simple, inverted planar construction prepared from solution was realized. This preliminary work was the precondition for the development of a fiber based OLED. In addition, OLEDs that were prepared using glass fibers as substrates and solution processed active and hole-transport layers will be shown.

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Kho, Samil, Sungjun Bae, and Donggeun Jung. "Effects of a Nanothin Al2O3 Cathode Buffer Layer on the Characteristics of Organic Light-emitting Diodes with Sputter-deposited Cathodes." Journal of Materials Research 17, no. 6 (June 2002): 1248–50. http://dx.doi.org/10.1557/jmr.2002.0186.

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Effects of an Al2O3 nanothin film between the emitting layer and the sputterdeposited cathode were studied for organic light-emitting diodes (OLEDs) with indium–tin–oxide, NN′-dephenyl-NN′-bis)(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine, tris(8-hydroxyquinoline)aluminum (Alq3), and aluminum (Al) as an anode, a hole transport layer, an emitting layer (EML), and a cathode, respectively. The performance of the OLEDs with sputter-deposited Al cathodes was inferior to that of the OLED with the evaporated Al cathode. However, the insertion of an Al2O3 nanothin film with a proper thickness between the EML and the sputter-deposited Al cathode was effective to alleviate performance degradation of the OLEDs with sputter-deposited Al cathodes in current flow and light emission. It is considered that both protection of EML by Al2O3 from the sputtering damage and higher luminance by the presence of a thin insulating layer between the EML and the cathode alleviated performance degradation of the OLED with an Al2O3 cathode buffer layer. The Al2O3 buffer layer could not alleviate quantum efficiency reduction caused by the sputtering damage.

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Lian, Cheng, Dan Young, Richard E. Randall, and Ifor D. W. Samuel. "Organic Light-Emitting Diode Based Fluorescence-Linked Immunosorbent Assay for SARS-CoV-2 Antibody Detection." Biosensors 12, no. 12 (December 5, 2022): 1125. http://dx.doi.org/10.3390/bios12121125.

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Immunodiagnostics have been widely used in the detection of disease biomarkers. The conventional immunological tests in central laboratories require expensive equipment and, for non-specialists, the tests are technically demanding and time-consuming, which has prevented their use by the public. Thus, point-of-care tests (POCT), such as lateral flow immunoassays, are being, or have been, developed as more convenient and low-cost methods for immunodiagnostics. However, the sensitivity of such tests is often a concern. Here, a fluorescence-linked immunosorbent assay (FLISA) using organic light-emitting diodes (OLEDs) as excitation light sources was investigated as a way forward for the development of compact and sensitive POCTs. Phycoerythrin (PE) was selected as the fluorescent dye, and OLEDs were designed with different emission spectra. The leakage light of different OLEDs for exciting PE was then investigated to reduce the background noise and improve the sensitivity of the system. Finally, as proof-of-principle that OLED-based technology can be successfully further developed for POCT, antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human serum was detected by OLED−FLISA.

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Ciobotaru, Iulia Corina, Monica Enculescu, Silviu Polosan, Ionut Enculescu, and Constantin Claudiu Ciobotaru. "Organic Light-Emitting Diodes with Electrospun Electrodes for Double-Side Emissions." Micromachines 14, no. 3 (February 25, 2023): 543. http://dx.doi.org/10.3390/mi14030543.

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Transparent conductive electrodes (TCE) obtained by the electrospinning method and gold covered were used as cathodes in the organic light-emitting diodes (OLEDs) to create double side-emission. The electro-active nanofibers of poly(methyl methacrylate) (PMMA) with diameters in the range of several hundreds of nanometers, were prepared through the electrospinning method. The nanofibers were coated with gold by sputtering deposition, maintaining optimal transparency and conductivity to increase the electroluminescence on both electrodes. Optical, structural, and electrical measurements of the as-prepared transparent electrodes have shown good transparency and higher electrical conductivity. In this study, two types of OLEDs consisting of indium tin oxide (ITO)/ poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS)/ Ir(III) complex (8-hydroxyquinolinat bis(2-phenylpyridyl) iridium–IrQ(ppy)2 20 wt% embedded in N, N′-Dicarbazolyl-4,4′-biphenyl (CBP) sandwich structure and either gold-covered PMMA electrospun nanoweb (OLED with electrospun cathode) were fabricated together with a similar structure containing thin film gold cathodes (OLED with thin film cathode). The luminance-current-voltage characteristics, the capacitance-voltage, and the electroluminescence properties of these OLEDs were investigated.

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Hyun, Young Jun, Seung Won Han, Dong Chan Lee, Jin Won Sun, Chang Woong Chu, and Jun Yeob Lee. "P‐200: N‐type Host Derived from Phenyl‐Triazine Moiety for Low Driving Voltage in Blue Phosphorescent Organic Light‐Emitting Diodes." SID Symposium Digest of Technical Papers 55, no. 1 (June 2024): 2147–49. http://dx.doi.org/10.1002/sdtp.18031.

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For commercialization of blue phosphorescent OLED, it is desirable to satisfy low driving voltage, high efficiency, and long device lifetime at the same time. In this work, we developed a new phenyl‐triazine type based PTHN‐2 host with oxasiline functional group by applying a novel molecular design strategy that modulates intermolecular distance and electron mobility. The PTNH‐2 host was compared with PTNH‐1 host with tetraphenylsilane functional group instead of oxasiline functional group. The fabricated blue phosphorescent OLEDs with PTNH‐2 as the N type host showed the driving voltage of 4.1 V and the external quantum efficiency of 22.0% relative to driving voltage of 4.5 V and external quantum efficiency of 18.3% collected from PTNH‐1 based blue phosphorescent OLED. Additionally, the device lifetime of the blue phosphorescent OLEDs was extended by more than 100% by replacing PTNH‐1 host with PTNH‐2 host. The driving voltage, quantum efficiency, device lifetime, and power efficiency of the blue phosphorescent OLEDs were dramatically improved by employing the PTNH‐2 host.

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Lim, Junseop, Jae-Min Kim, and Jun Yeob Lee. "85‐2: Prediction of Triplet Harvesting Ability in Blue Fluorescent Organic Light‐Emitting Diodes Using Deep Learning." SID Symposium Digest of Technical Papers 55, no. 1 (June 2024): 1179–82. http://dx.doi.org/10.1002/sdtp.17752.

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In this paper, we implemented new time dependent exciton decay model based on exciton dynamics using transient electroluminescence profile of fluorescent triplet‐triplet annihilation (TTA) orgarnic light‐emitting diodes (OLEDs). The prompt and delayed components of fluorescent TTA OLED could be distinguished quantitatively and accurate TTA ratio analysis was achieved using the new TTA model. In addition, predictive model of kinetic coefficients and TTA ratio was established using neural network of multilayer perception, and it demonstrated nearly perfect prediction ability of TTA ratio (determination coefficient, R2 = 0.999). The results of this study would contribute to understand TTA mechanisms deeply with exact estimation of major parameters of TTA OLEDs and help future OLED research using deep learning predictive model.

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Lee, Ho Won, Hyunjin Jeong, Young Kwan Kim, and Yunkyoung Ha. "Synthesis and Electroluminescent Property of New Orange Iridium Compounds for Flexible White Organic Light Emitting Diodes." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 7754–59. http://dx.doi.org/10.1166/jnn.2015.11205.

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Recently, white organic light-emitting diodes (OLEDs) have aroused considerable attention because they have the potential of next-generation flexible displays and white illuminated applications. White OLED applications are particularly heading to the industry but they have still many problems both materials and manufacturing. Therefore, we proposed that the new iridium compounds of orange emitters could be demonstrated and also applied to flexible white OLEDs for verification of potential. First, we demonstrated the chemical properties of new orange iridium compounds. Secondly, conventional two kinds of white phosphorescent OLEDs were fabricated by following devices; indium-tin oxide coated glass substrate/4,4-bis[N-(napthyl)-N-phenylamino]biphenyl/N,N- dicarbazolyl-3,5-benzene doped with blue and new iridium compounds for orange emitting 8 wt%/1,3,5-tris[N-phenylbenzimidazole-2-yl]benzene/lithium quinolate/aluminum. In addition, we fabricated white OLEDs using these emitters to verify the potential on flexible substrate. Therefore, this work could be proposed that white light applications can be applied and could be extended to additional research on flexible applications.

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Liu, C. H., C. H. Tesng, and C. P. Cheng. "Efficiency Improvement of Organic Light Emitting Diodes with Co-Deposited Hole Blocking Layer." Defect and Diffusion Forum 297-301 (April 2010): 561–66. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.561.

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There are several kinds of methods in improving the efficiency of organic light emitting diodes (OLEDs). In this work, we used a co-deposited hole blocking layer to improve the efficiency of OLEDs. The structure of the component is: ITO/ MTDATA(15 nm) /NPB(40 nm) /BCP(10 nm) /BCP: Alq(15 nm) /LiF(0.7 nm)/ Al(180 nm). We changed the mixing rate of the BCP:Alq layer to be capable of hole blocking and electron transporting, and then improved the efficiency of OLEDs. Finally, we prepared white light OLED with doping Rubrene in NPB. When the concentration of the NPB: Rubrene layer was 2.0 wt.%, the device could emit the white light at 100 mA/cm2, and the luminance was above 2300 cd/m2, and the color coordinate was x = 0.36, y = 0.37.

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Journal articles on the topic 'OLEDs'

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