Dissertations / Theses on the topic 'Terthiophenes'

Thesis presents synthesis and study of thiophene monomers, oligomers and polymers. The new series of thieno[3,4-b]pyrazine copolymers based on 3-dodecylthiophene and pyrazine monomers were prepared by oxidative polymerization with FeCl3. The effective synthetic method for preparation of 3-alkylthiophenes and thiophene oligomers was developed by optimizing of Kumada cross-couplig. The mentioned method could be realized for multikilos scale with possibility of transfer to pilot plant production. The second part of thesis focuses on synthesis and study of new thiophene compounds, which consist of both 2,3-diazo-1,3-butadiene bridge with two terminal chromophores and two thiophene units linked together via -position by pyrazine or hydrazine bridge. Finally, the new type of regular alternating copolymer consists of 2,2´:5´,2´´-terthiophene-5,5´-dicarboxylic acid (TEDA) and polyethyleneoxide (PEO) was prepared. Formation of polymer nano-subunits as separated phases in solid state was confirmed by TEM.

As a means of reducing the dependence on fossil fuels, generation of hydrogen (H₂) has been proposed as a route for storing energy in a chemical bond. To access this energy, H₂ can be combusted with oxygen or used in a fuel to release the energy stored in the chemical bond, while generating water as the byproduct. To generate the hydrogen necessary to fuel a hydrogen economy, an energy efficient and stable catalyst needs to be designed. The work presented in this thesis describes the investigation of a catalytic mimic inspired by the [FeFe]-hydrogenase enzyme. The design of this and similar mimics have been pursued as the active site of the enzyme is composed of readily available and abundant elements, and has a turnover rate of 6000-9000 molecules of H₂ s⁻¹. The catalyst in this work was studied via cyclic voltammetry and density functional theory calculations to determine the catalytic activity as well as a mechanism for H₂ production of the complex. The complex 2,5-bis-(2',2"-thiophen-2-yl)-thiophene-µ-3,4-dithiolato)diiron hexacarbonyl, 1, was prepared and found to catalyze the production of molecular hydrogen in CH₂Cl₂, however the overpotential for catalysis was not determined as the standard potential of acetic acid in CH₂Cl₂ is not known. Comparison of the catalytic potentials of terthiophene-cat to µ-(1,2-benzenedithiolato)diiron hexacarbonyl, 2, and µ-(3,4-thiophenedithiolato)diiron hexacarbonyl, 3, in CH₂Cl₂ showed that 1 had a less negative potential (0.14 V and 0.16 V, respectively) for the catalytic reduction of protons to H₂. Electrochemical investigations combined with density functional theory (DFT) indicated that 1 has an ECEC mechanism for the reduction of protons, where E is an electrochemical step and C is a chemical process. The proposed mechanism for 1 is similar to that of 2 and 3, with 1 catalyzing the production of H₂ using acetic acid at a less negative potential than 2 and 3.

The discovery of conducting and semiconducting polymers has opened the possibility to produce integrated circuits entirely of plastic with standard continuous printing techniques. Nowadays several of this polymers are commercial available, however the performances of this materials are strongly affected by their supramolecular order achieved after deposition. In this research, the influence of some standard printing techniques on the electrical performances of conjugated polymers is evidenced in order to realise logic devices with these materials.

碩士
國立臺北科技大學
有機高分子研究所
101
In this study, a series of new two-dimensional conjugated polymers with benzodithiophene (BDT) unit, including PTBDT、P3TBDT、P3TBDTDT and P3TBDTCN were designed and synthesized using Stille coupling polymerization methed. These polymers bear terthiophene groups as conjugated side-chains and vinyl groups as conjugated bridge to link the side-chains to polymer backbone. To enhance the solubility, each terminal thiophenes of the terthiophene unit was incorporated with one ethylhexyl group. To reduce the crowd of effect in PTBDT, two thiophene rings were inserted into the backbone as space to form P3TBDT；moreover, the two ends of terthiophene side group in P3TBDT were further chemically modified with two different acceptor units, 1,3-diethyl-2-thiobarbituric and ethyl-2-cyanoacetate, to yield P3TBDTDT and P3TBDTCN, respectively. All intermediates and monomers were characterized using 1H NMR, 13C NMR, COSY, HSQC, HMBC and HRESI mass spectrometry. The properties of as-synthesized copolymers were characterized by UV-vis absorption spectrometer, X-ray Diffractometer, photoelectron spectrometer AC-2 and cyclic voltammetry. Gel permeation chromatography (GPC) was employed to determine the molecular weight characteristics of the final polymers. Experimental results show that inserting two thiophenes as spacer into the main chain of P3TBDT improves the coplanarity and increases the effective conjugation length of the polymer backbone. Compared with PTBDT, P3TBDT exhibits a narrower bandgap, a broader absorption spectrum and an enhanced absorption coefficient. Moreover, the incorporation of electron-withdrawing units to the terthiophene side groups in P3TBDTDT and P3TBDTCN greatly red-shifts the absorption of terthiophene into visible range and overlap with the absorption of main-chain that substantially increases the light-harvesting capability of polymer in a specific wavelength region.

碩士
國立交通大學
應用化學系
83
In others' research showed that bithiophene and terthiophene rivatives have the great potentoal to be developed into therapeutic agents against infectious diseases or cancers. Some of them have the phototoxicity under UV light or sunlight. In the dark, one can increase the quantity and get the same effect. we want to use them as therapeutic agents, we have to increase their solubility in water or hydrophilic solvent and decrease the toxicity. Thus, our laboratory synthesize a series of new hydro- philic bithiophene and terthiophene derivatives, including: 5-(2- iminoethanol)-2,2'-bithiophene(5), 5-(2-methylaminoethanol)-2,2'- bithiophene(6), 5-(2-iminoethanol)-2,2':5',2"-terthiophene(7),(2- methylaminoethanol)-2,2':5',2"-terthiophene(8), 1,2-bis( 2,2'-bithiophene-5-imino)ethylene(9), 5-(2-methylaminoethylamine) -2,2'-bithiophene(10), 1,2-bis(2,2':5'2"-terthiophene-5-imino) ethylene(11), 5-(2-(2-imino)ethylaminoethanol)-2,2'-bithiophene( 12) and 5-(2-(2-imino)ethylaminoethanol)-2,2':5'2"-terthiophene( 13) for supplying advanced biological activity test.

碩士
國立臺北科技大學
有機高分子研究所
100
In this study, a series of new two-dimensional polythiophene derivatives with terthiophene as pendant group, including p(2EHT-BT), p(2EHT-TT), p(2EHT-DTT) and p(3EHT-DTT), were designed and synthesized. To enhance the solubility, the two terminal thiophene rings of the terthiophene unit were incorporated with ethylhexyl groups. Moreover, the bithiophene (BT) and fused thiophene families, thieno[3,2-b]thiophene (TT) and dithieno[3,2-b:2 '', 3 ''-a]thiophene (DTT), were applied as comonomer to vary the distance between two bulky terthiophene-bearing monomer and increase the extent of coplanarity of the polymer main chain. All intermediates, monomers and polymer products were characterized with 1H NMR, 13C NMR and EI mass spectrometry. Gel permeation chromatography (GPC) was employed to determine the molecular weight characteristics of the final polymers. As indicated by the XRD diffraction patterns, the insertion of BT and DTT as a spacer between two bulky monomer substantially increases the crystallinity of polymer chains. Also, the fused structure of the comonomer further enhances the crystallinity of the polymer. Additionally, both p(2EHT-DTT) and p(3EHT-DTT) exhibit more red-shifted absorption maxima and wider absorption spectra (350~660 nm) than those of p(2EHT-BT) and p(2EHT-TT), indicating the formers have longer conjugation length and better main-chain planarity compared with the latters. Importantly, CV measurements demonstrate that the HOMO level of these two two-dimensional polymers is apparently lower than that of P3HT, suggesting an improved environmental stability and an potential acceptor material for developing high-open-circuit voltage polymer solar cells.

碩士
正修科技大學
化工與材料工程研究所
97
Two series of light emitting single polymers (PFS series and PFTS series) are prepared by incorporating different contents of monomers into the main chain of polyfluorene. PFS series contain different contents of 2,2':5',2'-terthiophene moieties; PFTS series comprise 5 mol% 2,3,4,5-tetraphenyl thiophene (TP) and different amount of 2,2':5',2' -terthiophene moieties. The monomers and polymers have been characterized by mass, elemental analysis, 1H-NMR, 13C-NMR, UV/vis, GPC, thermogravimetric analysis, and fluorescence spectroscopy. The thermal properties of polymer were investigated by TGA. The decomposition temperatures (Td) of PFS series and PFTS series range from 319 to 402°C and 404 to 422°C, respectively. All differential scanning calorimetry (DSC) scans for the two series of polymers do not show any glass transition in the temperature range up to 300 °C. The optical properties of these polymers are studied by UV/vis and PL spectroscopic methods. The polymers of PFS series and PFTS series exhibit the maximum absorption in the range of 373~382 nm and 374~381nm in liquid solution, respectively. The range of 367~378 nm and 376~379 nm in thin film demonstrate the maximum absorption for both, respectively. The polymers of PFS series and PFTS series exhibit the maximum emission in the range of 411~414 nm and 413~415 nm in liquid solution, respectively. The range of 503~592 nm and 502~543 nm in thin film demonstrate the maximum absorption for both, respectively. Single layer devices (ITO/PEDOT:PSS/polymer/LiF/Al) are fabricated with these polymers. The color coordinates (0.32, 0.35) of PFTS-3 devices in the best condition for the turn-on voltage of 4.5V and the highest brightness of 558 cd/m2 could meet pure white light (0.33, 0.33) of the ideal CIE chromaticity coordinates. We can find the feed ratio of the white light emitting single polymers is 92 mol% fluorine moieties, 5 mol% TP moieties and 3 mol% 2,2':5',2'-terthiophene moieties. According to cyclic voltametry (CV), HOMO level of PFS series and PFTS series could reveal in the range of -5.61~ -5.73 eV and -5.69~ -5.73 eV, respectively. The range of -2.69~ -2.79 eV and -2.74~ -2.76 eV could indicate LUMO level of them, respectively.

碩士
國立中央大學
化學學系
107
The power conversion efficiency（PCE）of perovskite solar cells（PSCs）has shown a significant enhancement from 3.8 % in 2009 to 23.7 % in 2018. To increase the PCE, developing a hole-transporting material（HTM）which has superior ability of positive charge extraction and transportation is one of the important factors. In this article, three terthiophene-based hole-transporting materials named WZ40, WZ102, WZ103 have been synthesized. The compounds of WZ series exhibit amorphous property and appropriate thermal stability. However, the perovskite solar cell employing WZ102 generates a power conversion efficiency of 11.91 %, which is higher than the power conversion efficiency of 10.23 % based on PEDOT:PSS. The better performance gives it potential as a promising HTM for the further advance of PSCs.

博士
國立臺灣大學
高分子科學與工程學研究所
103
In this thesis, a series of novel polythiophenes with terthiophene-vinylene moieties as conjugated side-chains were designed and synthesized by Stille polycondensation. The correlations between the chemical structure and properties of such polymers and their effect on the performance of solar cells were intensively investigated. In the first part, two isomeric polythiophenes with terthiophene-vinylene (TTV) as conjugated side-chains, PBTTTV-h and PBTTTV-v, were designed, synthesized, and characterized. Although both polymers show low-lying HOMO energy levels and good solubility, the architecture of conjugated side chain significantly affects the optical, electrochemical, molecular self-assembling and photovoltaic properties. The PBTTTV-h displays two distinct absorption peaks in UV-Vis spectrum and a crystal polymer as verified by XRD; on the other hand, the PBTTTV-v displays a single broad absorption peak and is an amorphous material. Moreover, the BHJ solar cell fabricated from PBTTTV-h/PC71BM exhibited a higher power conversion efficiency (PCE) of 4.75 % under AM1.5G illumination at 100 mWcm-2 than PBTTTV-v/PC71BM of 4.00 %. Based on the results of the previous part that the two-dimensional polythiophene with parallel TTV conjugated side chains has good crystallinity, we further varied the anchoring site of alkyl groups on the conjugated side chain and substitute fused thiophenes in different sizes, TT and DTT, for BT as a spacer to control the spatial distance between bulky terthiophene-bearing monomers. The results clearly indicate the length of π-spacer is a crucial factor to the crystallinity of these 2D-polythiophenes as well as the anchoring site of alkyl chains and the coplanirity of main chain apparently influence the degree of molecular packing and the d-spacing of crystallites. Under AM1.5G illumination at 100 mWcm-2, the cell based on PBTTTV-h2/PC61BM exhibits the best PCE of 4.62%. In the third part, the 2D conjugated copolymers, PBTTTV-h-r-PBTDBT, containing 12% and 23% of 2, 1, 3-benzothiadiazole (BTD) were synthesized by Stille random-copolymerization and their optical, electrochemical, charge transport and photovoltaic properties were investigated. Both copolymers show a broader absorption spectrum, covering the spectral range from 300 nm up to 750 nm, and a reduced optical bandgap of 1.68 eV. The low content of BTD unit in PBTTTV-h-r-PBTDBT allowed preservation of many important properties of PBTTTV-h, including low-lying HOMO and high crystallinity. Under AM1.5G illumination at 100 mWcm-2, the polymer solar cell based on PBTTTV-h-r-PBTDBT-12%/PC71BM exhibits the best PCE of 5.31% with an open-circuit voltage (Voc) of 780 mV, a short-circuit current density (Jsc ) of 10.82 mAcm2, and a fill factor (FF) of 62.92 %. The IPCE measurements revealed a strong photo response from the random copolymers up to 750 nm, with IPCE values above 40% from 300 nm to 650 nm for PBTTTV-h-r-PBTDBT. These results indicate that the incorporation of acceptor units into a 2D-polymer by random copolymerization provide a simple and effective route toward polymers with a broad photocurrent response in PSCs. In last part, two new copolymers were designed, synthesized, characterized and applied in polymer solar cells (PSCs) as donor materials. Copolymer PBTTTVDK attaching two electron-withdrawing heptanoyl groups at TTV conjugated side chains showed a deeper HOMO energy level, better solubility, and red-shifted absorption of conjugated side chains. By introduction of strong electron-withdrawing BTD unit, PBTTTVDK-r-BTD possessed further red-shifted absorption band with absorption onset at 743 nm and effectively improved the coplanity of polymer backbone and ability of self-assembling to enhance carrier mobility. The bulk-heterojunction PSCs based on PBTTTVDK/PC61BM and PBTTTVDK-r-BTD/PC61BM displayed PCE of 1.52% and 4.17%, respectively, under the illumination of AM1.5G, 100 mW cm-2. We have successfully designed, synthesized and characterized a family of polythiophenes with a terthiophene-vinylene (TTV) as conjugated side-chains and applied them in PSC device. The achievement of structure-property correlations will be benefit of developing high performance 2D-conjugated polymeric semiconductor materials.

碩士
國立臺灣大學
高分子科學與工程學研究所
102
We employed all-atom molecular dynamics (AAMD) simulation and the quantum mechanical (QM) methods to explore the correlation between the molecular conformation and the UV absorption behaviors of terthiophene-based conjugated polymers. The four model systems examined here are PBTTTV-v, PBTTTV-h, H-PBTTTV-v and H-PBTTTV-h. We focus on the effects of side-chain architecture on the two-dimensional extended conjugation properties of the UV absorption spectra of polythiophenes. First, we observe the molecular conformation displaying disordered state of polymer chains within dilute solution via AAMD. In the PBTTTV-v, PBTTTV-h, H-PBTTTV-v and H-PBTTTV-h molecules, due to a large steric hindrance from the linkage between main chain and side chain, they have broader torsional angle distribution of main chain (τMain chain_A) and side chain (τSide chain_B). Because of the free motion of single bonds, the single bond linkages between main chain and side chain don’t intend to preserve a coplanar conformation as the H-PBTTTV-v and H-PBTTTV-h molecules. In contrast, as for the PBTTTV-v and PBTTTV-h polymers with vinyl linkage tend to keep a coplanar conformation. Then, we explore the UV absorption spectra of PBTTTV-v and PBTTTV-h molecules via QM. We notice that PBTTTV-v and PBTTTV-h have the two-dimensional extended conjugation properties in the UV absorption spectra, which make the UV absorption spectra more complicated. On the other hand, we observe the molecular orbital and discover the electron cloud may scatter along the main chain to side chain. As a result, we constitute several segments from the molecular orbitals by adjusting each segment’s fraction. The resultant UV absorption spectra of PBTTTV-v and PBTTTV-h show good match to the experimental results. When the single bonds are substituted for the vinyl linkages, the UV absorption spectra of H-PBTTTV-v and H-PBTTTV-h dimer show two peaks in the same range. The two absorption peaks are from either the main chain or the side chain. In the future, we will modify the torsional angle of molecular conformation within AAMD. We will systematically explore the correlation between molecular conformation and optoelectronic properties of PBTTTV-v, PBTTTV-h, H-PBTTTV-v and H-PBTTTV-h.

Conducting polymers display properties such as high conductivity, light weight and redox activity giving them great potential for use in many applications. Polythiophenes have proved to be particularly useful because they are readily functionalised and have good chemical stability. The purpose of this work was to investigate the effect of electron-withdrawing and electron-donating substituents on the synthesis and properties of polythiophenes. Initial work entailed the synthesis of a series of styryl-substituted terthiophenes. Polymerisation of these materials using both chemical and electrochemical methods was found to produce predominantly short chain oligomers (n < 4) and insoluble material that could not be further processed. An analogous series of styryl-substituted terthienylenevinylene materials were electrochemically oxidised for comparison to the terthiophene series. These materials were also found to produce predominantly dimer and short oligomers, but with the expected higher conjugation length than the corresponding terthiophene oligomers. To enhance polymerisation and increase the solubility of the resulting materials, the polymerisation of styryl-terthiophenes with alkyl and alkoxy functionalities was investigated. The properties of the resulting polymeric materials were determined using electrochemistry, mass spectrometry, spectroscopy and microscopy. The alkoxy substituted polymer was found to have a longer average polymer length than the corresponding alkyl derivative (~n = 11 compared to ~n = 6), but was less soluble (78% compared to 100%). It was found, however, that by increasing the alkoxy chain length from 6 carbons to 10 carbons, the solubility of the polymer could be increased to 97% without affecting the average polymer length. The alkoxy-substituted polymers were observed to be very stable in the oxidised, conducting state compared to the alkyl-substituted polymer, which appeared to be more stable in the neutral, non-conducting state. It was found that these soluble materials could be separated into fractions of different length polymers by using sequential soxhlet extractions in different solvents. Preliminary investigations were made into the suitability of these soluble oligomeric and polymeric materials for use in photovoltaic, actuator and organic battery applications and promising results were achieved for actuator and battery functions. In addition, the solubility of these materials allowed nano- and micro-structured fibre and fibril surfaces to be prepared for use in high surface area electrodes.

博士
國立臺灣大學
藥學研究所
95
Part I. Studies of the Active Ingredient of Sauropus Androgynus on Reduction of the Body Weight Gain in vitro and in vivo. The raw juice of young sticks and leaves of Sauropus androgynus (SA) has been widely used as a natural food for body weight reduction in Taiwan and Southeast Asia. When taking for more than three months, an endemic of SA-associated obliterative bronchiolitis develops. Lung transplantation is carried out in severe cases. To study the toxic effect and perhaps anti-obesity activity, we separated the SA extract into three parts, namely CHCl3, EtOAc and n-BuOH fractions. The n-BuOH fraction was further purified to 3-O-β-D-glucosyl-(1→6)-β-D-glucosyl-kaempferol (GGK). When CHCl3 and n-BuOH fractions treated Bcl-2/NIH3T3 (a Bcl-2 overexpressed cell line) and NIH3T3 cells for 36 h, the genomic DNA of cells upon CHCl3 fraction treatment appeared smearing in both cells. DNA appeared fragmenting in NIH3T3 cells treated with n-BuOH fraction, while Bcl-2/NIH3T3 cells were not affected. In animal studies, Wistar rats received SA fractions for 28 day. Serum GOP and cholesterol levels in the n-BuOH group were significantly lower than that in control group. The n-BuOH group exhibited bronchiolitis obliterans and organizing pneumonia (BOOP) in lung and fatty change with occasional apoptosis in liver from histopathological observations. CHCl3 group showed organizing pneumonia with hemorrhage in lung and micro and macrovesicular fatty change in liver. Results indicate that n-BuOH fraction of SA extract induces apoptosis, that is distinctive from the effect of CHCl3 fraction of SA extract. SA, used as health supplement for control of body weight, may contain certain active ingredients responsible for anti-obesity. A preadipocyte 3T3-L1 cell line was employed to study the effect of SA on adipogenesis. Cells treated with the toxic fractions CHCl3 and n-BuOH displayed a significant reduction in number and size of oil droplets although CHCl3 fraction is more cytotoxic than n-BuOH fraction by PI flow cytometry assay. Furthermore, GGK purified from n-BuOH fraction demonstrates inhibition of the middle stage of adipogenesis progress through preventing oil droplets maturation, ATPase activation and the key protein PPARγ. We next looked at weight reduction by SA in animals. Wistar rats received 6 or 60 mg/kg of GGK as well partial purified fractions of SA extract daily for 28 days. Sixty milligrams per kilogram GGK treatment significantly reduced food intake in rats by 15% (p < 0.05). The reduced food intake corresponded to decreases in body weight in the high or low dose GGK groups, as compared to the control groups. Serum levels of free triglyceride decreased in GGK-treated rats; in contrast, the cholesterol concentration increased. GGK treatment led to maintainable reductions in daily food intake and body weight without any obvious toxicity to Wistar rats. Thus, after appropriate modification GGK might be potentially a safe novel compound for anti-obesity treatment. Distribution and metabolism of GGK is important for its development to be clinically applicable. Wistar rats were orally administered with GGK 60 mg/kg. We then collect plasma, urine and feces for high-performance liquid chromatography (HPLC) analysis. The HPLC chromatogram of plasma, collected at 12th h, appeared a major peak of which did not overlap with GGK peak. The major GGK metabolite peak was assumed to be 3-O-β-D-glucosyl-kaempferol-monoglucuronide (GKG`) using either glucosidase or glucuronidase enzyme reactions. HPLC analysis of urine collected at 24th h revealed the presence of glucurono-conjugated derivative, 3-O-β-D-glucosyl-kaempferol (GK) and kaempferol (K). Like urine, GK and K were found in feces. GK maybe absorbed into the body directly and was conjugated with glucuronide in liver, and then enter systemic circulation. GK hydrolyzed from GGK may be an important entity to reduce adipogenesis and become an so called anti-obesity agent. Part II. Screening of Terthiophene Derivatives for Anticancer Activity and Studies of Their Mechanisms. Echinops grijisii, a Chinese herbal medicine, has been used as antipyretic and antidote over a long period of time. Synthetic terthiophenes via chemical modification could inhibit protein kinase A, mitogen activated protein kinase and protein tyrosine kinase. We investigated the effect of four terthiophenes: NSC-646270, NSC-647455, NSC-663561 and NSC-658878, in 11 human cancer cell lines. All terthiophenes exhibited strong cytotoxicity in A498, SW480, NPC-039 and NPC-039N1 cells with the IC50 < 0.5 μM. Among them, A498 cells had the strongest response to terthiophenes cytotoxicity. Terthiophenes at 10 μM were able to compete with ethidium bromide for DNA intercalation and at 1μM induce intracellular DNA fragmentation in A498. The fragmenting DNA accumulated in sub G1 phase of cell cycle distribution by flowcytometry analysis. Cytotoxic effect of terthiophenes may be related to induction of apoptosis in A498 cells. The mechanism of terthiophenes was extensively studied in A498 upon NSC-646270 treatment. There was a 50% increase in TNFα and TNFR1 expression levels after 1 μM NSC-646270 treatment in A498 cells for 12 h. At the same time, caspases 8 increased 2 folds and caspase 3 increased 1.5 folds, while Bid decreased significantly. Furthermore, a large reduction of Bcl-2 protein started from 12th h and Bax and Bad were significantly induced. The release of cytochrome c from mitocondria into the cytosol was detected in cells upon NSC-646270 treatment for 9 h. The enzyme activity of caspase-3, -6 and -9 increased around 2 folds when cells were exposed to NSC-646270 for 24 h. In conclusion, the mechanism of terthiophenes on induction of apoptosis in A498 involves two pathways of caspase activation: (i) death receptor-mediated caspase-8 and (ii) mitochondria-mediated caspase-9. Development of terthiophenes as anticancer drugs needs to be further evaluated.

The discovery of conducting and semiconducting polymers has opened the possibility to produce integrated circuits entirely of plastic with standard continuous printing techniques. Nowadays several of this polymers are commercial available, however the performances of this materials are strongly affected by their supramolecular order achieved after deposition. In this research, the influence of some standard printing techniques on the electrical performances of conjugated polymers is evidenced in order to realise logic devices with these materials.