Journal articles: 'Perovskitas'

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Cota Leal, Marcos Alan, Merida Sotelo Lerma, and Manuel Quevedo López. "FABRICACIÓN DE PELÍCULAS DE PEROVSKITA (CH3NH3PbI3-XClX) POR DROP CASTING." Biotecnia 19 (September 21, 2017): 34–37. http://dx.doi.org/10.18633/biotecnia.v19i0.408.

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Las perovskitas de haluro de alquilamonio híbridas, han sido estudiadas en los últimos años. Principalmente, los plumbatos de trihalogenuro de alquilamonio (por ejemplo, CH3NH3PbI3), por sus excelentes propiedades como un semiconductor con el transporte de carga ambipolar, la absorción del espectro a (400-800 nm) intervalo de banda ajustable y gran longitud de difusión. Las Perovskitas han tenido un gran éxito en el campo de las celdas solares, donde han alcanzado un alto grado de eficiencia (20.1%) y dispositivo de bajo costo. Sin embargo, la perovskita es muy sensible a la humedad que provoca la degradación. En este trabajo se presenta una ruta para la síntesis de películas de perovskita (CH3NH3PbI3-xClx) enfocada en un proceso de bajo costo. Para la fabricación de las películas se utiliza el método de drop casting, partiendo de una solución de yoduro de plomo (PbI2) y cloruro de metilamonio (CH3NH3Cl), el depósito de las películas se lleva acabo a 160°C y adicionalmente se da un tratamiento térmico a las mismas. Las películas de perovskita obtenidas se caracterizaron por microscopía electrónica de barrido, difracción de rayos X, UV Vis.

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Paiva, A. K. O., J. J. S. Batista, J. B. M. Wanderley, F. M. M. Borges, and D. M. A. Melo. "Estudo comparativo de perovskitas La0,6Ca0,4(Co,Mn)O3 obtidas pelo método dos precursores poliméricos para utilização em catálise de combustão." Cerâmica 60, no. 353 (March 2014): 144–48. http://dx.doi.org/10.1590/s0366-69132014000100019.

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Materiais com estrutura perovskita são catalisadores em potencial para reduzir as emissões de componentes poluentes no meio ambiente. Na síntese das perovskitas, vários métodos têm sido propostos. Neste trabalho, os sistemas manganato de lantânio e cobaltato de lantânio com substituição parcial de cálcio (La0,6Ca0,4MnO3 e La0,6Ca0,4CoO3, respectivamente), foram sintetizados pelo método dos precursores poliméricos. Os pós obtidos após 4 h a 300 ºC foram calcinados a 700 e 900 ºC por 4 h, e caracterizados pelas técnicas de análise termogravimétrica, difração de raios X e microscopia eletrônica de varredura. Comparando os difratogramas das composições de manganato e cobaltato de lantânio, à medida que a temperatura aumenta ocorre um aumento da cristalinidade, mais evidenciada no manganato. As curvas de análise termogravimétrica apresentaram estabilidades térmicas semelhantes, com maior perda de massa para o material com cobalto. As perovskitas obtidas foram monofásicas e apresentaram boa porosidade, o que torna estes pós potenciais catalisadores para reações de combustão.

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Hueso, L. E., A. Fondado, J. Rivas, F. Rivadulla, and M. A. López-Quintela. "Efectos intergranulares en perovskitas de manganeso nanocristalinas." Boletín de la Sociedad Española de Cerámica y Vidrio 39, no. 3 (June 30, 2000): 259–62. http://dx.doi.org/10.3989/cyv.2000.v39.i3.837.

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Wanderley, J. B. M., F. M. M. Borges, J. P. Ribeiro, P. M. Pimentel, and D. M. A. Melo. "Síntese e estudo microestrutural de perovskita do tipo La0,8Ca0,2MO3 (M = Co ou Mn) com gelatina como precursor orgânico para aplicação em catálise automotiva." Cerâmica 59, no. 349 (March 2013): 156–59. http://dx.doi.org/10.1590/s0366-69132013000100018.

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Materiais com estrutura perovskita são potenciais catalisadores para prevenir a emissão de componentes poluentes no meio ambiente. Vários métodos têm sido propostos para a síntese desses materiais visando produzir materiais homogêneos com tamanho de partícula nanométrico. Neste trabalho os compostos manganato de lantânio e cobaltato de lantânio com substituição parcial de cálcio foram sintetizados com gelatina como agente de polimerização, visando sua utilização como catalisadores automotivos. Esse método de síntese foi utilizado porque permite a obtenção de fases cristalinas com pós homogêneos e porosos. Os pós obtidos a 300 ºC/4 h foram calcinados a 700 e 900 ºC/4 h e caracterizados pelas técnicas de análise termogravimétrica, difração de raios X e microscopia eletrônica de varredura. As perovskitas obtidas foram monofásicas, manométricas, porosas e com propriedades adequadas para aplicação em catálise automotiva.

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Deluque Toro, C. E., D. A. Landínez Téllez, Jairo Arbey Rodríguez, J. Roa-Rojas, and A. Mosquera. "Propiedades estructurales, electrónicas y magnéticas de la perovskita BiRO3." Respuestas 16, no. 2 (December 15, 2011): 14–19. http://dx.doi.org/10.22463/0122820x.367.

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Presentamos un estudio detallado de las propiedades estructurales, los estados, electrónicos y magnéticos de las perovskitas del tipo BiRO3, con R=Fe, Co, Ni, en su estructura cúbica, con grupo de simetría Pm-3m. En la obtención de los resultados se utilizó el método de Spin Polarizado de Ondas Planas Aumentadas y Linealizadas (SP-FP-LAPW) dentro del marco de la teoría DFT. El estudio estructural consistió en calcular las energías de cohesión en función del volumen y mediante su ajuste a la ecuación de estado de Murnaghan se determinaron el módulo de volumen, el volumen de equilibrio y de éste el valor de constante de red. En el estudio de las características electrónicas se han determinado curvas de energía en contra del número de onda (k) y la densidad de estado (DOS) para cada polarización de spin.Palabras clave: perovskitas BiRO3 , DFT, propiedades electrónicas.

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Kozhukharov, V. S., M. S. Machkova, and N. V. Brashkova. "Evolución térmica de precursores de nitratos para el procesado de perovskitas de lantánidos." Boletín de la Sociedad Española de Cerámica y Vidrio 37, no. 6 (December 30, 1998): 461–66. http://dx.doi.org/10.3989/cyv.1998.v37.i6.989.

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López-Ortega, Leonardo, Brayann Aldair Gutiérrez-García, Miguel Arteaga-Varela, Alejandro de Jesús Herrera-Carbajal, Eleazar Salinas-Rodríguez, and Ventura Rodríguez-Lugo. "Estudio teórico de las propiedades estructurales y electrónicas en sistemas BaTiO3 y BaZrO3." Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI 8, Especial (December 12, 2020): 54–59. http://dx.doi.org/10.29057/icbi.v8iespecial.6322.

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Se realizó un estudio teórico relativo dos perovskita de tipo ABO3, Titanato de Bario (BaTiO3) y Zirconato de Bario (BaZrO3), optimizando los parámetros para un pseudopotencial Perdew-Burke-Erszerhof (PBE) de tipo ultrasuave, mediante el uso del código SIESTA el cual está sustentado en la Teoría del Funcional de la Densidad (DFT). Así mismo se optimizaron las estructuras, alterando el parámetro de red de ambas perovskitas permitiendo determinar la más estable. Para las estructuras de mínima energía del BaTiO3 y BaZrO3 se obtuvieron parámetros de red correspondientes a 4.104 Å y 4.276 Å respectivamente, que difieren en poca cantidad a los reportados experimentalmente cuyos valores son de 4.004 Å y 4.256 Å mostrando que SIESTA permite obtener aproximaciones superiores al 97%, asimismo la estructura de bandas mostro el comportamiento indirecto en la transición de la banda de valencia a la de conducción para ambos materiales con características de semiconductores al poseer valores de 1.64 y 2.77 eV respectivamente.

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Pedroza-Rojas, Brandon, Brayan Javier Lorenzano-Hernández, Alejandro de Jesús Herrera-Carbajal, Miguel Arteaga-Varela, Mónica Araceli Camacho-González, María Isabel Reyes-Valderrama, and Ventura Rodríguez-Lugo. "Estudio teórico fundamental comparativo de perovskitas: NaNbO3 y SrTiO3." Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI 8, Especial (December 12, 2020): 60–67. http://dx.doi.org/10.29057/icbi.v8iespecial.6324.

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En el presente estudio teórico ab initio comparativo se utiliza el código SIESTA®, mediante la Teoría del Funcional de la Densidad (DFT) para comprender las propiedades estructurales y electrónicas de la fase cúbica en el equilibrio de la geometría de dos perovskitas complejas: NaNbO3 y SrTiO3. Se emplean dos pseudopotenciales base: Aproximación de Gradiente Generalizado (GGA) por los autores Perdew-Burke-Ernzerhof, y Aproximación de Densidad Local (LDA) por Ceperley-Alder. Los parámetros de red obtenidos para el NaNbO3 son a0= 3.900 y 4.040 Å con una precisión del 98.86 y 97.6%. Para el SrTiO3 se obtuvieron parámetros de red de a0= 3.969 y 3.811 Å con una precisión de 92.8 y 97.6% respectivamente de cada pseudopotencial. Se demuestra que el comportamiento de ambas estructuras de bandas tiene una transición electrónica indirecta particular con spin no polarizado, con un ancho de banda prohibida de ∼1.28 eV para el NaNbO3 y ∼2.0 eV para el SrTiO3 con el potencial de intercambio-correlación LDA y una estructura de bandas argumentativa de la fiable aplicación de estos materiales en fase cúbica para dispositivos opto-electrónicos.

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Kharton, V. V., A. P. Viskup, G. C. Mather, A. A. Yaremchenko, E. N. Naumovich, and F. M. B. Marques. "Conductividad mixta en perovskitas de La(Ga,Mg,Nb)O_3-Î´." Boletín de la Sociedad Española de Cerámica y Vidrio 38, no. 6 (December 30, 1999): 647–52. http://dx.doi.org/10.3989/cyv.1999.v38.i6.912.

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Villanueva-Ibáñez, M., M. A. Hernández-Pérez, P. N. Rivera Arzola, and M. A. Flores-González. "Síntesis en medio poli-alcohólico y caracterización de Perovskitas BaHfO3 y BaZrO3." Matéria (Rio de Janeiro) 18, no. 4 (December 2013): 1501–9. http://dx.doi.org/10.1590/s1517-70762013000400011.

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Los materiales tipo perovskita (ABO3) presentan considerable interés tecnológico, sus propiedades dependen de los elementos A y B que los sustituyan. Para la elaboración de materiales tipo perovskita se han empleado diversos métodos. En este trabajo se presentan los resultados obtenidos para el BaHfO3 y BaZrO3 utilizando la síntesis poliol. Se usaron sales inorgánicas disueltas en dietilenglicol y los materiales recuperados han sido tratados térmicamente a 700 °C y 900 °C. El análisis por difracción de rayos X reveló la estructura cúbica tipo perovskita y se observaron adicionalmente picos correspondientes a las fases secundarias de BaCO3 y MO2 (M=Hf o Zr) en ambos materiales. Los espectros obtenidos por FTIR pusieron en evidencia la presencia de BaCO3. Las observaciones por microscopía electrónica de barrido revelaron para ambos casos, materiales muy compactos conformados por sub-estructuras más pequeñas en forma de alambre de diámetro aproximado a 900 nm. Para temperaturas de calcinado entre 700ºC y 900ºC se observó un cambio remarcable en la morfología con materiales disgregados conformados por partículas más pequeñas. Los análisis en microscopía electrónica en transmisión revelaron que los materiales tratados a la mayor temperatura están constituidos por pequeños cristales inferiores a 15 nm.

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Deluque-Toro, Críspulo Enrique, David A. Landínez-Téllez, and Jairo Roa-Rojas. "Ab-initio analysis of magnetic, structural, electronic and thermodynamic properties of the Ba2TiMnO6 manganite." DYNA 85, no. 205 (April 1, 2018): 27–36. http://dx.doi.org/10.15446/dyna.v85n205.68517.

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Los materiales de tipo perovskita que incluyen elementos magnéticos son relevantes debido a sus perspectivas de aplicabilidad tecnológica en la industria de la espintrónica. En este trabajo fueron investigadas las propiedades magnéticas, estructurales, electrónicas y termodinámicas de la manganita de tipo perovskita Ba2TiMnO6. Los cálculos fueron realizados a través del método del potencial de ondas planas aumentadas y linealizadas (FP-LAPW), en el marco de la Teoría del Funcional Densidad (DFT), con efectos de intercambio y correlación en las aproximaciones de gradiente generalizado (GGA) y de densidad local (LDA), incluyendo polarización de espín. A partir de la minimización de la energía en función del volumen, usando la ecuación de estado de Murnaghan se obtuvieron los parámetros de equilibrio de la red las propiedades de cohesión de este compuesto. El estudio de la estructura electrónica se basó en el análisis de la densidad de estados (DOS) y la estructura de bandas, mostrando que este compuesto evidencia un momento magnético efectivo de 3.0 μB. la dependencia con la temperatura y la presión del calor específico, la entropía, el coeficiente de expansión térmica, la temperatura de Debye y el parámetro de Grüneisen fueron calculados mediante DFT a partir de la ecuación de estado, usando el modelo cuasi-armónico de Debye. Se encontró que el calor específico CV≈CP para temperaturas por debajo de T = 400 K, con un límite de Dulong-Petit relativamente mayor que el reportado para perovskitas simples.

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Godoi, Glauber S., and Dulcina P. F. de Souza. "Efeito de íons aliovalentes nas propriedades elétricas de céria dopada com ítria." Matéria (Rio de Janeiro) 13, no. 3 (September 2008): 512–21. http://dx.doi.org/10.1590/s1517-70762008000300010.

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A alta temperatura de operação da PaCOS pode causar a formação de fases resistivas isolantes na interface eletrólito-catodo o que contribui para a perda de eficiência da pilha, podendo-se citar como exemplo a formação de zirconatos na interface manganita de lantânio dopada com estrôncio (LSM) - zircônia estabilizada com ítria (ZEI). Outro aspecto importante em PaCOS é o uso de material de eletrólito com uma condutividade iônica maior do que a da zircônia em temperaturas mais baixas. Essa característica é importante para a redução da temperatura de operação da PaCOS minimizando os problemas relacionados com a alta temperatura de operação, sendo Céria dopada com ítria (CY) um exemplo desse tipo de material. Por isso, para o uso de CY como eletrólito em PaCOS é importante avaliar a possibilidade de formação de fase isolante envolvendo esse material e o material do catodo, como perovskitas de lantânio. Para avaliar possíveis reações entre céria dopada com ítria e dois tipos de perovskitas usadas como catodo, LSM and LSCF, foi realizado, neste trabalho, a dopagem de CY com dois conjuntos de íons: La, Sr, Mn e La, Sr, Fe, Co. A dopagem provocou aumento da condutividade elétrica do grão enquanto que a condutividade efetiva do contorno de grão decresceu. Contudo a condutividade total não foi comprometida com a dopagem. A dopagem com La, Mn e Sr forneceu amostra de Céria dopada com Itria mais estáveis em alta temperatura e atmosfera redutora.

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Castro, Dayane A. de, Yagly G. dos S. Gomes, Ariadne C. Eduardo, Nara L. de Oliveira, Kellen C. M. Borges, Rosana de F. Gonçalves, Maria R. de C. Santos, and Mario G. Junior. "Síntese de Condutores Protônicos de Cerato de Estrôncio (SrCeO 3) pelo Método dos Precursores Poliméricos para Uso em Células a Combustíveis." Revista Processos Químicos 13, no. 26 (March 9, 2020): 97–104. http://dx.doi.org/10.19142/rpq.v13i26.545.

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O crescente aumento tecnológico traz consigo a necessidade de se produzir novos materiais que atendam tal evolução de maneira sustentável. Nesse sentido, o estudo de perovskitas de cerato de estrôncio SrCeO3 torna-se de grande relevância, visto que estes materiais possuem propriedade de condução protônica e são bastante utilizadas como eletrólito sólido para células a combustíveis de óxido sólido, as quais são muito importantes para a geração de energia com baixas ou nenhuma emissões de poluentes, por meio de combustíveis renováveis. Logo, o presente trabalho visou sintetizar o SrCeO3 pelo método do precursor polimérico dopado e não dopado e caracterizá-los estruturalmente.

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DE PAULA, Márcio, and Regina Helena Porto FRANCISCO. "USE OF DUST X-RAY DIFFRACTION IN THE CHARACTERIZATION OF PEROVSKITAS TYPE FERRITES." Periódico Tchê Química 05, no. 9 (January 20, 2008): 23–30. http://dx.doi.org/10.52571/ptq.v5.n09.2008.janeiro/4_pgs_23_30.pdf.

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The X-ray diffraction is one experimental method very important on characterization solids compounds. In the case of polycrystalline samples, the x-ray powder diffraction allows for the identification of the solid phase and the characterization of structural changes. The present paper was prepared any antiferromagnetic ceramic phases, bicalcic ferrite derivate (Ca2Fe2O5) by solid state reaction from pulverized reagents and mixed manually. These were heated in the Pt melting pan, in air oven at temperature between 1000 and 1450oC for 12h. The occurrence of reaction with reagents and the products obtained were identified and structurally characterized by X-ray diffraction by polycrystalline sample. Mixtures of regents CaCO3, SrCO3, BaCO3, Fe2O3, Nb2O5, Have been made with various symmetries: a) Ba2Fe2O5, b) CaBaFe2O5, c) Ba2FeNbO6, d) Ca2Fe2O5, (e) Ba2Nb2O7, (f) Ca2Nb2O7, (g) Sr2Nb2O7, (h) CaBaFeNbO6. The products obtained showed that O2 of the air participated of reactions by providing the anions oxides required for obtaining the cubic phase. The formation of this phase was also helped by the presence of barium and niobium, since in the absence of these elements, can be seen the formation of orthorhombic phase, characteristic of Ca2Fe2O5.

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Moura, J. S., L. A. Silva, M. C. Rangel, and G. C. Araújo. "Síntese e caracterização de perovskitas do tipo LaNi1-xCu xO3 para a purificação de hidrogênio para PaCOS." Matéria (Rio de Janeiro) 15, no. 3 (2010): 472–79. http://dx.doi.org/10.1590/s1517-70762010000300009.

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Neste trabalho, foram estudados sólidos do tipo LaNi1-xCuxO3 (x = 0,0; 0,3 e 0,5), com estrutura perovskita, visando a desenvolver catalisadores destinados à produção de hidrogênio de alta pureza na reforma interna de células a combustível de óxido sólido (SOFC). Observou-se que as condições experimentais usadas na preparação favoreceram a incorporação quantitativa dos cátions ao precursor e a formação dos sólidos com estrutura perovskita. Esses materiais mostraram diferentes propriedades redutoras e a presença do cobre favoreceu a estabilidade da estrutura perovskita. As propriedades catalíticas das amostras obtidas foram avaliadas na reação de deslocamento de monóxido de carbono com vapor d'água (WGSR, water gas shift reaction), uma etapa importante de purificação do hidrogênio, no processo de reforma de hidrocarbonetos. Os resultados mostraram que os catalisadores são promissores para esta reação, apresentando atividade muito superior à de um catalisador comercial de óxido de ferro contendo cromo e cobre; isto foi atribuído à tendência das amostras em favorecer o mecanismo adsortivo, provavelmente decorrente de uma alta mobilidade dos oxigênios da rede cristalina. O valor mais elevado de atividade catalítica foi apresentado pela Amostra LaNi0,5Cu0,5O3, considerada o catalisador de melhor desempenho.

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Zhou, Dahua, Leyong Yu, Peng Zhu, Hongquan Zhao, Shuanglong Feng, and Jun Shen. "Lateral Structured Phototransistor Based on Mesoscopic Graphene/Perovskite Heterojunctions." Nanomaterials 11, no. 3 (March 5, 2021): 641. http://dx.doi.org/10.3390/nano11030641.

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Due to their outstanding optical properties and superior charge carrier mobilities, organometal halide perovskites have been widely investigated in photodetection and solar cell areas. In perovskites photodetection devices, their high optical absorption and excellent quantum efficiency contribute to the responsivity, even the specific detectivity. In this work, we developed a lateral phototransistor based on mesoscopic graphene/perovskite heterojunctions. Graphene nanowall shows a porous structure, and the spaces between graphene nanowall are much appropriated for perovskite crystalline to mount in. Hot carriers are excited in perovskite, which is followed by the holes’ transfer to the graphene layer through the interfacial efficiently. Therefore, graphene plays the role of holes’ collecting material and carriers’ transporting channel. This charge transfer process is also verified by the luminescence spectra. We used the hybrid film to build phototransistor, which performed a high responsivity and specific detectivity of 2.0 × 103 A/W and 7.2 × 1010 Jones, respectively. To understand the photoconductive mechanism, the perovskite’s passivation and the graphene photogating effect are proposed to contribute to the device’s performance. This study provides new routes for the application of perovskite film in photodetection.

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Landínez Téllez, David Arsenio, Jairo Roa-Rojas, Gabriel Peña-Rodríguez, Fabio Enrique Fajardo Tolosa, and Jairo Arbey Rodríguez Martinez. "DFT Calculation of Electronic Structure for the CaLaBaCu3O7 Superconducting Perovskite." Respuestas 15, no. 2 (February 17, 2016): 47–51. http://dx.doi.org/10.22463/0122820x.374.

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Se reportan las propiedades estructurales y electrónicas de la perovskita en la fase cristalográfica tetragonal. Este material tiene un carácter superconductor con una temperatura crítica alrededor de 80 K. En el compuesto , la transición tetragonal a ortorrómbico no aparece cuando se disminuye el contenido de oxígeno, como ocurre en el caso del . A pesar de su importancia, son pocos los cálculos teóricos de la estructura electrónica y de bandas de energía para esta familia de perovskitas. Se presentan los posibles mecanismos superconductores en el plano de y cadenas O, en este tipo de material. Los cálculos se realizaron para el compuesto en el estado normal por medio del método FP-LAPW, en la aproximación GGA, siempre dentro del formalismo de la teoría del funcional de densidad (DFT). En primer lugar, el estudio consistió en encontrar la energía del compuesto, el volumen óptimo y el módulo de volumen. También se optimizó la relación c/a, donde a y c son los parámetros de red de la celda cristalográfica tetragonal. A partir de estos resultados, se llevó a cabo un estudio detallado de las propiedades electrónicas para este material. El objetivo de esta investigación es la determinación de las relaciones de dispersión y el cálculo de la densidad de los estados (DOS). También se determinó la proyección de la DOS en los orbitales atómicos. Se concluye que el orden de Cu y los átomos de oxígeno en los planos estructurales son importantes para el comportamiento superconductor del .Palabras clave: DFT, estructura electrónica, superconductor de alta temperatura, CaLaBaCu3O7.

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de los Santos Guerra, J., P. Barranco, F. Calderón, D. Garcia, and J. A. Eiras. "Substituição do Pb2+ por La3+ na rede cristalina do sistema ferroelétrico PZT (53/47): influência nas propriedades estruturais, microestruturais e elétricas." Cerâmica 51, no. 317 (March 2005): 19–23. http://dx.doi.org/10.1590/s0366-69132005000100005.

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Propriedades estruturais, microestruturais e elétricas foram investigadas em cerâmicas ferroelétricas perovskitas do sistema PLZT em função do conteúdo de lantânio. Foi analisada a composição com razão Zr/Ti=53/47 que se encontra na região do contorno de fases morfotrópico. As cerâmicas foram obtidas pelo método convencional de mistura de óxidos utilizando reagentes de alta pureza. A análise por difração de raios X revelou a presença das fases tetragonal e romboédrica, com uma diminuição contínua do fator de tetragonalidade (c/a) com o aumento da concentração de La. Corpos cerâmicos com alta densificação foram obtidos como confirmado por microscopia eletrônica de varredura. A diminuição da temperatura de transição de fase ferroelétrica-paraelétrica (Tm), segundo o aumento da concentração de lantânio, é discutida em função da incorporação do cátion La3+ na rede cristalina do PZT.

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Peña, O., K. Ghanimi, C. Moure, D. Gutiérrez, and P. Durán. "Inversión de espín en perovskitas Gd(Me,Mn)O₃ (Me = Co, Ni)." Boletín de la Sociedad Española de Cerámica y Vidrio 43, no. 3 (June 30, 2004): 706–9. http://dx.doi.org/10.3989/cyv.2004.v43.i3.480.

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Meyer, Edson, Dorcas Mutukwa, Nyengerai Zingwe, and Raymond Taziwa. "Lead-Free Halide Double Perovskites: A Review of the Structural, Optical, and Stability Properties as Well as Their Viability to Replace Lead Halide Perovskites." Metals 8, no. 9 (August 27, 2018): 667. http://dx.doi.org/10.3390/met8090667.

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Perovskite solar cells employ lead halide perovskite materials as light absorbers. These perovskite materials have shown exceptional optoelectronic properties, making perovskite solar cells a fast-growing solar technology. Perovskite solar cells have achieved a record efficiency of over 20%, which has superseded the efficiency of Gräztel dye-sensitized solar cell (DSSC) technology. Even with their exceptional optical and electric properties, lead halide perovskites suffer from poor stability. They degrade when exposed to moisture, heat, and UV radiation, which has hindered their commercialization. Moreover, halide perovskite materials consist of lead, which is toxic. Thus, exposure to these materials leads to detrimental effects on human health. Halide double perovskites with A2B′B″X6 (A = Cs, MA; B′ = Bi, Sb; B″ = Cu, Ag, and X = Cl, Br, I) have been investigated as potential replacements of lead halide perovskites. This work focuses on providing a detailed review of the structural, optical, and stability properties of these proposed perovskites as well as their viability to replace lead halide perovskites. The triumphs and challenges of the proposed lead-free A2B′B″X6 double perovskites are discussed here in detail.

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Mitchell, Roger H., Mark D. Welch, and Anton R. Chakhmouradian. "Nomenclature of the perovskite supergroup: A hierarchical system of classification based on crystal structure and composition." Mineralogical Magazine 81, no. 3 (June 2017): 411–61. http://dx.doi.org/10.1180/minmag.2016.080.156.

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AbstractOn the basis of extensive studies of synthetic perovskite-structured compounds it is possible to derive a hierarchy of hettotype structures which are derivatives of the arisotypic cubic perovskite structure (ABX3), exemplified by SrTiO3 (tausonite) or KMgF3 (parascandolaite) by: (1) tilting and distortion of the BX6 octahedra; (2) ordering of A- and B-site cations; (3) formation of A-, B- or X-site vacancies. This hierarchical scheme can be applied to some naturally-occurring oxides, fluorides,hydroxides, chlorides, arsenides, intermetallic compounds and silicates which adopt such derivative crystal structures. Application of this hierarchical scheme to naturally-occurring minerals results in the recognition of a perovskite supergroup which is divided into stoichiometric and non-stoichiometricperovskite groups, with both groups further divided into single ABX3 or double A2BB'X6 perovskites. Subgroups, and potential subgroups, of stoichiometric perovskites include: (1) silicate single perovskites of the bridgmanite subgroup;(2) oxide single perovskites of the perovskite subgroup (tausonite, perovskite, loparite, lueshite, isolueshite, lakargiite, megawite); (3) oxide single perovskites of the macedonite subgroup which exhibit second order Jahn-Teller distortions (macedonite, barioperovskite); (4) fluoride singleperovskites of the neighborite subgroup (neighborite, parascandolaite); (5) chloride single perovskites of the chlorocalcite subgroup; (6) B-site cation ordered double fluoride perovskites of the cryolite subgroup (cryolite, elpasolite, simmonsite); (7) B-site cation orderedoxide double perovskites of the vapnikite subgroup [vapnikite, (?) latrappite]. Non-stoichiometric perovskites include: (1) A-site vacant double hydroxides, or hydroxide perovskites, belonging to the söhngeite, schoenfliesite and stottite subgroups; (2) Anion-deficient perovskitesof the brownmillerite subgroup (srebrodolskite, shulamitite); (3) A-site vacant quadruple perovskites (skutterudite subgroup); (4) B-site vacant single perovskites of the oskarssonite subgroup [oskarssonite]; (5) B-site vacant inverse single perovskites of the coheniteand auricupride subgroups; (6) B-site vacant double perovskites of the diaboleite subgroup; (7) anion-deficient partly-inverse B-site quadruple perovskites of the hematophanite subgroup.

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Nascimento, C. C., R. E. S. Bretas, and M. R. Morelli. "Síntese da perovskita [KNbO3]0,9[BaNi0,5Nb0,5O3-δ]0,1 por combustão em solução." Cerâmica 65, no. 373 (January 2019): 45–53. http://dx.doi.org/10.1590/0366-69132019653732444.

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Resumo O desenvolvimento de perovskitas ferroelétricas capazes de absorver a luz visível, particularmente KBNNO - [KNbO3]0,9[BaNi0,5Nb0,5O3-δ]0,1 (band-gap Eg= 1,39 eV), tem encorajado a aplicação desses materiais na camada ativa de células solares. Em dispositivos fotovoltaicos, esses materiais podem permitir a obtenção de voltagens superiores à magnitude de seus band-gaps e contribuir para uma separação de portadores de cargas mais eficiente. A obtenção de KBNNO na forma de pó de elevada área superficial pode ser uma estratégia para posterior incorporação do óxido em células compostas de materiais processados a baixas temperaturas. Neste trabalho, reporta-se pela primeira vez o uso da rota de combustão em solução como uma alternativa para a síntese de KBNNO. As amostras foram caracterizadas por DRX, MEV, EDS, TG/DSC e espectroscopia UV-vis. As propriedades ópticas confirmaram a contribuição na absorção da luz visível e um band-gap próximo do valor ideal para aplicações fotovoltaicas.

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Yang, Bilin, Yujun Xie, Pan Zeng, Yurong Dong, Qiongrong Ou, and Shuyu Zhang. "Tightly Compacted Perovskite Laminates on Flexible Substrates via Hot-Pressing." Applied Sciences 10, no. 6 (March 11, 2020): 1917. http://dx.doi.org/10.3390/app10061917.

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Pressure and temperature are powerful tools applied to perovskites to achieve recrystallization. Lamination, based on recrystallization of perovskites, avoids the limitations and improves the compatibility of materials and solvents in perovskite device architectures. In this work, we demonstrate tightly compacted perovskite laminates on flexible substrates via hot-pressing and investigate the effect of hot-pressing conditions on the lamination qualities and optical properties of perovskite laminates. The optimized laminates achieved at a temperature of 90 °C and a pressure of 10 MPa could sustain a horizontal pulling pressure of 636 kPa and a vertical pulling pressure of 71 kPa. Perovskite laminates exhibit increased crystallinity and a crystallization orientation preference to the (100) direction. The optical properties of laminated perovskites are almost identical to those of pristine perovskites, and the photoluminescence quantum yield (PLQY) survives the negative impact of thermal degradation. This work demonstrates a promising approach to physically laminating perovskite films, which may accelerate the development of roll-to-roll printed perovskite devices and perovskite tandem architectures in the future.

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McDonald, Calum, Chengsheng Ni, Paul Maguire, Paul Connor, John Irvine, Davide Mariotti, and Vladimir Svrcek. "Nanostructured Perovskite Solar Cells." Nanomaterials 9, no. 10 (October 18, 2019): 1481. http://dx.doi.org/10.3390/nano9101481.

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Over the past decade, lead halide perovskites have emerged as one of the leading photovoltaic materials due to their long carrier lifetimes, high absorption coefficients, high tolerance to defects, and facile processing methods. With a bandgap of ~1.6 eV, lead halide perovskite solar cells have achieved power conversion efficiencies in excess of 25%. Despite this, poor material stability along with lead contamination remains a significant barrier to commercialization. Recently, low-dimensional perovskites, where at least one of the structural dimensions is measured on the nanoscale, have demonstrated significantly higher stabilities, and although their power conversion efficiencies are slightly lower, these materials also open up the possibility of quantum-confinement effects such as carrier multiplication. Furthermore, both bulk perovskites and low-dimensional perovskites have been demonstrated to form hybrids with silicon nanocrystals, where numerous device architectures can be exploited to improve efficiency. In this review, we provide an overview of perovskite solar cells, and report the current progress in nanoscale perovskites, such as low-dimensional perovskites, perovskite quantum dots, and perovskite-nanocrystal hybrid solar cells.

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Korolev, Viacheslav I., Anatoly P. Pushkarev, Petr A. Obraztsov, Anton N. Tsypkin, Anvar A. Zakhidov, and Sergey V. Makarov. "Enhanced terahertz emission from imprinted halide perovskite nanostructures." Nanophotonics 9, no. 1 (December 27, 2019): 187–94. http://dx.doi.org/10.1515/nanoph-2019-0377.

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AbstractLead halide perovskites were known to be a prospective family of materials for terahertz (THz) generation. On the other hand, perovskite nanostructures, nanoantennas, and metasurfaces allow tailoring perovskites optical characteristics, resulting in more efficient interaction with incident or emitted light. Moreover, the perovskites are robust materials against formation of defects caused by mechanical deformations and can be efficiently nanostructured by various high throughput methods. In this work, we have enhanced THz emission from MAPbI3 perovskite upon femtosecond laser irradiation using nanoimprint lithography. The formed nanostructures not only improve absorption of the incident laser pulses, but also lead to a non-symmetric near-field distribution. As a result, we have enhanced the efficiency of THz emission from the nanostructured perovskite by 3.5 times as compared with a smooth perovskite film. Our results paved the way for a new application of large-scale perovskite nanostructuring, making halide perovskites competitive with more expensive conventional semiconductors for THz generation.

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Heidari Gourji, Fatemeh, and Dhayalan Velauthapillai. "A Review on Cs-Based Pb-Free Double Halide Perovskites: From Theoretical and Experimental Studies to Doping and Applications." Molecules 26, no. 7 (April 1, 2021): 2010. http://dx.doi.org/10.3390/molecules26072010.

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Despite the progressive enhancement in the flexibility of Pb-based perovskites for optoelectronic applications, regrettably, they are facing two main challenges; (1) instability, which originates from using organic components in the perovskite structure, and (2) toxicity due to Pb. Therefore, new, stable non-toxic perovskite materials are demanded to overcome these drawbacks. The research community has been working on a wide variety of Pb-free perovskites with different molecular formulas and dimensionality. A variety of Pb-free halide double perovskites have been widely explored by different research groups in search for stable, non-toxic double perovskite material. Especially, Cs-based Pb-free halide double perovskite has been in focus recently. Herein, we present a review of theoretical and experimental research on Cs-based Pb-free double halide perovskites of structural formulas Cs2M+M3+X6 (M+ = Ag+, Na+, In+ etc.; M3+= Bi3+, In3+, Sb3+; X = Cl−, Br−, I¯) and Cs2M4+X6 (M4+ = Ti4+, Sn4+, Au4+ etc.). We also present the challenges faced by these perovskite compounds and their current applications especially in photovoltaics alongside the effect of metal dopants on their performance.

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Wyn Jones, Eurig, Peter James Holliman, Leon Bowen, Arthur Connell, Christopher Kershaw, and Diana Elizabeth Meza-Rojas. "Hybrid Al2O3-CH3NH3PbI3 Perovskites towards Avoiding Toxic Solvents." Materials 13, no. 1 (January 6, 2020): 243. http://dx.doi.org/10.3390/ma13010243.

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We report the synthesis of organometal halide perovskites by milling CH3NH3I and PbI2 directly with an Al2O3 scaffold to create hybrid Al2O3-CH3NH3PbI3 perovskites, without the use of organic capping ligands that otherwise limit the growth of the material in the three dimensions. Not only does this improve the ambient stability of perovskites in air (100 min versus 5 min for dimethylformamide (DMF)-processed material), the method also uses much fewer toxic solvents (terpineol versus dimethylformamide). This has been achieved by solid-state reaction of the perovskite precursors to produce larger perovskite nanoparticles. The resulting hybrid perovskite–alumina particles effectively improve the hydrophobicity of the perovskite phase whilst the increased thermal mass of the Al2O3 increases the thermal stability of the organic cation. Raman data show the incorporation of Al2O3 shifts the perovskite spectrum, suggesting the formation of a hybrid 3D mesoporous stack. Laser-induced current mapping (LBIC) and superoxide generation measurements, coupled to thermogravimetric analysis, show that these hybrid perovskites demonstrate slightly improved oxygen and thermal stability, whilst ultra-fast X-ray diffraction studies using synchrotron radiation show substantial (20×) increase in humidity stability. Overall, these data show considerably improved ambient stability of the hybrid perovskites compared to the solution-processed material.

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Wong, Walter P. D., John V. Hanna, and Andrew C. Grimsdale. "The classification of 1D `perovskites'." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 77, no. 3 (May 20, 2021): 408–15. http://dx.doi.org/10.1107/s2052520621004376.

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There has been a huge amount of interest in perovskites recently and new structures of hybrid perovskites are frequently reported. The classification of perovskites has been unambiguous in the discussion of 3D and layered 2D perovskites due to the dimensional constraints. However, in 1D perovskites, the additional degrees of freedom have resulted in a large number of possible structural configurations. The new proposed notation aims to classify these structures based on the connectivity of the octahedra of the perovskite, which has a periodic repeating pattern. However, the notation should be restricted to simple 1D perovskites and haloplumbate structures as the notation would become too cumbersome when applied to an exotic framework which has 3D characteristics, such as perovskite polytypes.

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Era, Masanao, Yumeko Komatsu, and Naotaka Sakamoto. "Enhancement of Exciton Emission in Lead Halide-Based Layered Perovskites by Cation Mixing." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3338–42. http://dx.doi.org/10.1166/jnn.2016.12295.

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Spin-coated films of a lead halide, PbX: X = I and Br, layered perovskites having cyclohexenylethyl ammonium molecule as an organic layer, which were mixed with other metal halide-based layered perovskites consisting of various divalent metal halides (for example, CaI2, CdI2, FeI2, SnBr2 and so on), were prepared. The results of X-ray diffraction measurements exhibited that solid solution formation between PbX-based layered perovskite and other divalent metal halide-based layered perovskites was observed up to very high molar concentration of 50 molar% in the mixed film samples when divalent cations having ionic radius close to that of Pb2+ were employed. In the solid solution films, the exciton emission was much enhanced at room temperature. Exciton emission intensity of PbI-based layered perovskite mixed with CaI-based layered perovskite (20 molar%) is about 5 times large that of the pristine PbI-based layered perovskite, and that of PbBr-based layered perovskite mixed with SnBr-based layered perovskite (20 molar%) was also about 5 times large that of the pristine PbBr-based layered perovskite at room temperature.

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Cardona Vasquez, Jorge Andres, Maria Elena Gomez, David Arsenio Landinez Tellez, and Jairo Roa Rojas. "Producción y caracterización de nuevos materiales multiferróicos basados en el sistema LCMO/BLZT Ba0.9La0.067Ti0.91Zr0.09O3/ La0.67Ca0.33MnO3." Respuestas 17, no. 2 (July 1, 2012): 81–92. http://dx.doi.org/10.22463/0122820x.426.

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Reportamos los detalles de síntesis y caracterización estructural eléctrica y magnética del sistema multiferroico Ba0.9La0.067Ti0.91Zr0.09O3/ La0.67Ca0.33MnO3. Se han preparado mediante la técnica de reacción de estado sólido mezclas con diferentes porcentajes de masa de la manganita de lantano y calcio La0.67Ca0.33MnO3 (LCMO), en su fase ferromagnética, y el titanatozirconato de bario y lantano Ba0.9La0.067Ti0.91Zr0.09O3 (BLZT) el cual ha sido reportado como ferroeléctrico. Patrones de difracción de rayos X muestran que los materiales han reaccionado dando lugar a nuevos materiales con estructura tipo perovskita con simetría tetragonal, grupo espacial P4mm (#99), la estructura de los materiales fue refinada usando el método de Rietveld. Curvas de magnetización FC y ZFC muestran dos transiciones de fase, una de ellas por arriba de 200 K y la otra por debajo de 50 K, dichas transiciones has sido asociadas con dos diferentes regímenes magnéticos en los cuales se han medido curvas de histéresis confirmando que la relación entre el campo aplicado y la magnetización no tiene un comportamiento lineal. Medidas de espectroscopía de impedancias muestran un carácter ferroeléctrico con pérdida dieléctrica, comportamiento que es confirmado mediante curvas de polarización en los materiales sintetizados.Reportamos los detalles de síntesis y caracterización estructural eléctrica y magnética del sistema multiferroico Ba0.9La0.067Ti0.91Zr0.09O3/ La0.67Ca0.33MnO3. Se han preparado mediante la técnica de reacción de estado sólido mezclas con diferentes porcentajes de masa de la manganita de lantano y calcio La0.67Ca0.33MnO3 (LCMO), en su fase ferromagnética, y el titanatozirconato de bario y lantano Ba0.9La0.067Ti0.91Zr0.09O3 (BLZT) el cual ha sido reportado como ferroeléctrico. Patrones de difracción de rayos X muestran que los materiales han reaccionado dando lugar a nuevos materiales con estructura tipo perovskita con simetría tetragonal, grupo espacial P4mm (#99), la estructura de los materiales fue refinada usando el método de Rietveld. Curvas de magnetización FC y ZFC muestran dos transiciones de fase, una de ellas por arriba de 200 K y la otra por debajo de 50 K, dichas transiciones has sido asociadas con dos diferentes regímenes magnéticos en los cuales se han medido curvas de histéresis confirmando que la relación entre el campo aplicado y la magnetización no tiene un comportamiento lineal. Medidas de espectroscopía de impedancias muestran un carácter ferroeléctrico con pérdida dieléctrica, comportamiento que es confirmado mediante curvas de polarización en los materiales sintetizados.Palabras clave: Perovskitas, multiferróico, superparamagnetismo, refinamiento rietveld.

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Wang, Fangfang, Qing Chang, Yikai Yun, Sizhou Liu, You Liu, Jungan Wang, Yinyu Fang, et al. "Hole-Transporting Low-Dimensional Perovskite for Enhancing Photovoltaic Performance." Research 2021 (May 28, 2021): 1–11. http://dx.doi.org/10.34133/2021/9797053.

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Halide perovskites with low-dimensionalities (2D or quasi-2D) have demonstrated outstanding stabilities compared to their 3D counterparts. Nevertheless, poor charge-transporting abilities of organic components in 2D perovskites lead to relatively low power conversion efficiency (PCE) and thus limit their applications in photovoltaics. Here, we report a novel hole-transporting low-dimensional (HT2D) perovskite, which can form a hole-transporting channel on the top surface of 3D perovskite due to self-assembly effects of metal halide frameworks. This HT2D perovskite can significantly reduce interface trap densities and enhance hole-extracting abilities of a heterojunction region between the 3D perovskite and hole-transporting layer. Furthermore, the posttreatment by HT2D can also reduce the crystal defects of perovskite and improve film morphology. As a result, perovskite solar cells (PSCs) can effectively suppress nonradiative recombination, leading to an increasement on photovoltage to >1.20 V and thus achieving >20% power conversion efficiency and >500 h continuous illumination stability. This work provides a pathway to overcome charge-transporting limitations in low-dimensional perovskites and delivers significant enhancements on performance of PSCs.

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Bartel, Christopher J., Christopher Sutton, Bryan R. Goldsmith, Runhai Ouyang, Charles B. Musgrave, Luca M. Ghiringhelli, and Matthias Scheffler. "New tolerance factor to predict the stability of perovskite oxides and halides." Science Advances 5, no. 2 (February 2019): eaav0693. http://dx.doi.org/10.1126/sciadv.aav0693.

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Predicting the stability of the perovskite structure remains a long-standing challenge for the discovery of new functional materials for many applications including photovoltaics and electrocatalysts. We developed an accurate, physically interpretable, and one-dimensional tolerance factor, τ, that correctly predicts 92% of compounds as perovskite or nonperovskite for an experimental dataset of 576 ABX3 materials (X = O2−, F−, Cl−, Br−, I−) using a novel data analytics approach based on SISSO (sure independence screening and sparsifying operator). τ is shown to generalize outside the training set for 1034 experimentally realized single and double perovskites (91% accuracy) and is applied to identify 23,314 new double perovskites (A2BB′X6) ranked by their probability of being stable as perovskite. This work guides experimentalists and theorists toward which perovskites are most likely to be successfully synthesized and demonstrates an approach to descriptor identification that can be extended to arbitrary applications beyond perovskite stability predictions.

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Burger, Stefan, Shivani Grover, Keith T. Butler, Hanna L. B. Boström, Ricardo Grau-Crespo, and Gregor Kieslich. "Tilt and shift polymorphism in molecular perovskites." Materials Horizons 8, no. 9 (2021): 2444–50. http://dx.doi.org/10.1039/d1mh00578b.

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Zhang, Taiyang, Yuetian Chen, Miao Kan, Shumao Xu, Yanfeng Miao, Xingtao Wang, Meng Ren, Haoran Chen, Xiaomin Liu, and Yixin Zhao. "MA Cation-Induced Diffusional Growth of Low-Bandgap FA-Cs Perovskites Driven by Natural Gradient Annealing." Research 2021 (August 18, 2021): 1–11. http://dx.doi.org/10.34133/2021/9765106.

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Low-bandgap formamidinium-cesium (FA-Cs) perovskites of FA1-xCsxPbI3 (x<0.1) are promising candidates for efficient and robust perovskite solar cells, but their black-phase crystallization is very sensitive to annealing temperature. Unfortunately, the low heat conductivity of the glass substrate builds up a temperature gradient within from bottom to top and makes the initial annealing temperature of the perovskite film lower than the black-phase crystallization point (~150°C). Herein, we take advantage of such temperature gradient for the diffusional growth of high-quality FA-Cs perovskites by introducing a thermally unstable MA+ cation, which would firstly form α-phase FA-MA-Cs mixed perovskites with low formation energy at the hot bottom of the perovskite films in the early annealing stage. The natural gradient annealing temperature and the thermally unstable MA+ cation then lead to the bottom-to-top diffusional growth of highly orientated α-phase FA-Cs perovskite, which exhibits 10-fold of enhanced crystallinity and reduced trap density (~3.85×1015 cm−3). Eventually, such FA-Cs perovskite films were fabricated into stable solar cell devices with champion efficiency up to 23.11%, among the highest efficiency of MA-free perovskite solar cells.

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Kim, Young-Hoon, Himchan Cho, and Tae-Woo Lee. "Metal halide perovskite light emitters." Proceedings of the National Academy of Sciences 113, no. 42 (September 27, 2016): 11694–702. http://dx.doi.org/10.1073/pnas.1607471113.

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Twenty years after layer-type metal halide perovskites were successfully developed, 3D metal halide perovskites (shortly, perovskites) were recently rediscovered and are attracting multidisciplinary interest from physicists, chemists, and material engineers. Perovskites have a crystal structure composed of five atoms per unit cell (ABX3) with cation A positioned at a corner, metal cation B at the center, and halide anion X at the center of six planes and unique optoelectronic properties determined by the crystal structure. Because of very narrow spectra (full width at half-maximum ≤20 nm), which are insensitive to the crystallite/grain/particle dimension and wide wavelength range (400 nm ≤ λ ≤ 780 nm), perovskites are expected to be promising high-color purity light emitters that overcome inherent problems of conventional organic and inorganic quantum dot emitters. Within the last 2 y, perovskites have already demonstrated their great potential in light-emitting diodes by showing high electroluminescence efficiency comparable to those of organic and quantum dot light-emitting diodes. This article reviews the progress of perovskite emitters in two directions of bulk perovskite polycrystalline films and perovskite nanoparticles, describes current challenges, and suggests future research directions for researchers to encourage them to collaborate and to make a synergetic effect in this rapidly emerging multidisciplinary field.

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Akinbami, O., G. N. Ngubeni, F. Otieno, R. Kadzutu-Sithole, E. C. Linganiso, Z. N. Tetana, S. S. Gqoba, K. P. Mubiayi, and N. Moloto. "The effect of temperature and time on the properties of 2D Cs2ZnBr4 perovskite nanocrystals and their application in a Schottky barrier device." Journal of Materials Chemistry C 9, no. 18 (2021): 6022–33. http://dx.doi.org/10.1039/d1tc00264c.

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2D hybrid perovskites are promising materials for solar cell applications, in particular, cesium-based perovskite nanocrystals as they offer the stability that is absent in organic–inorganic perovskites.

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Hiragond, Chaitanya B., Niket S. Powar, and Su-Il In. "Recent Developments in Lead and Lead-Free Halide Perovskite Nanostructures towards Photocatalytic CO2 Reduction." Nanomaterials 10, no. 12 (December 21, 2020): 2569. http://dx.doi.org/10.3390/nano10122569.

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Perovskite materials have been widely considered as emerging photocatalysts for CO2 reduction due to their extraordinary physicochemical and optical properties. Perovskites offer a wide range of benefits compared to conventional semiconductors, including tunable bandgap, high surface energy, high charge carrier lifetime, and flexible crystal structure, making them ideal for high-performance photocatalytic CO2 reduction. Notably, defect-induced perovskites, for example, crystallographic defects in perovskites, have given excellent opportunities to tune perovskites’ catalytic properties. Recently, lead (Pb) halide perovskite and their composites or heterojunction with other semiconductors, metal nanoparticles (NPs), metal complexes, graphene, and metal-organic frameworks (MOFs) have been well established for CO2 conversion. Besides, various halide perovskites have come under focus to avoid the toxicity of lead-based materials. Therefore, we reviewed the recent progress made by Pb and Pb-free halide perovskites in photo-assisted CO2 reduction into useful chemicals. We also discussed the importance of various factors like change in solvent, structure defects, and compositions in the fabrication of halide perovskites to efficiently convert CO2 into value-added products.

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Liu, Zhengzheng, Sihao Huang, Juan Du, Chunwei Wang, and Yuxin Leng. "Advances in inorganic and hybrid perovskites for miniaturized lasers." Nanophotonics 9, no. 8 (March 11, 2020): 2251–72. http://dx.doi.org/10.1515/nanoph-2019-0572.

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AbstractThe rapid advancement of perovskite-based optoelectronics devices has caught the world’s attention due to their outstanding properties, such as long carrier lifetime, low defect trap density, large absorption coefficient, narrow linewidth and high optical gain. Herein, the photonic lasing properties of perovskites are reviewed since the first stimulated emission of perovskites observed in 2014. The review is mainly focused on 3D structures based on their inherently active microcavities and externally passive microcavities of the perovskites. First, the fundamental properties in terms of crystal structure and optical characteristics of perovskites are reviewed. Then the perovskite lasers are classified into two sections based on the morphology features: the ability/inability to support lasing behaviors by themselves. Every section is further divided into two kinds of cavities according to the light reflection paths (Standing wave for the Fabry–Pérot cavity and travelling wave for the Whispering-Gallery-Mode cavity). The lasing performance involves fabrication methods, cavity sizes, thresholds, quality factors, pumping sources, etc. Finally, some challenges and prospects for perovskite lasers are given.

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Supianto, Mulya, Suyanta Suyanta, and Indriana Kartini. "An Interplay Role between Ammonium and Halide Anions as Additives in Perovskite CH₃NH₃PbI₃." Materials Science Forum 948 (March 2019): 287–93. http://dx.doi.org/10.4028/www.scientific.net/msf.948.287.

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Methylammonium lead trihalide perovskites have emerged as attractive materials for solar cell applications. The major eminence of this materials can be crystallized via various solution methods to produce the solid state of thin films. However, the crystallinity of perovskite depends on the composition of perovskites. Here, we study NH4Cl and NH4Br as precursor additives for improving crystallinity of perovskites. Perovskite was synthesized by mixing precursor solutions of CH3NH3I and Pb(Ac)2with or without additives NH4Cl and NH4Br using the one-step spin-coating method. By characterizing the thin films using XRD, SEM and UV-Vis spectrophotometer, we found anion Cl and Br performed an important role toward crystallinity, morphology, and optical absorption of perovskites, respectively. Meanwhile, ammonium has assisted to facile remove the residual DMSO solvent confirmed by FTIR. These results shed light on using ammonium halides as potentially dual side additives in the synthesis of perovskites.

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Cheng, Lu, Chang Yi, Yunfang Tong, Lin Zhu, Gunnar Kusch, Xiaoyu Wang, Xinjiang Wang, et al. "Halide Homogenization for High-Performance Blue Perovskite Electroluminescence." Research 2020 (December 24, 2020): 1–10. http://dx.doi.org/10.34133/2020/9017871.

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Metal halide perovskite light-emitting diodes (LEDs) have achieved great progress in recent years. However, bright and spectrally stable blue perovskite LED remains a significant challenge. Three-dimensional mixed-halide perovskites have potential to achieve high brightness electroluminescence, but their emission spectra are unstable as a result of halide phase separation. Here, we reveal that there is already heterogeneous distribution of halides in the as-deposited perovskite films, which can trace back to the nonuniform mixture of halides in the precursors. By simply introducing cationic surfactants to improve the homogeneity of the halides in the precursor solution, we can overcome the phase segregation issue and obtain spectrally stable single-phase blue-emitting perovskites. We demonstrate efficient blue perovskite LEDs with high brightness, e.g., luminous efficacy of 4.7, 2.9, and 0.4 lm W-1 and luminance of over 37,000, 9,300, and 1,300 cd m-2 for sky blue, blue, and deep blue with Commission Internationale de l’Eclairage (CIE) coordinates of (0.068, 0.268), (0.091, 0.165), and (0.129, 0.061), respectively, suggesting real promise of perovskites for LED applications.

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Hirose, Kei, Ryosuke Sinmyo, and John Hernlund. "Perovskite in Earth’s deep interior." Science 358, no. 6364 (November 9, 2017): 734–38. http://dx.doi.org/10.1126/science.aam8561.

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Silicate perovskite-type phases are the most abundant constituent inside our planet and are the predominant minerals in Earth’s lower mantle more than 660 kilometers below the surface. Magnesium-rich perovskite is a major lower mantle phase and undergoes a phase transition to post-perovskite near the bottom of the mantle. Calcium-rich perovskite is proportionally minor but may host numerous trace elements that record chemical differentiation events. The properties of mantle perovskites are the key to understanding the dynamic evolution of Earth, as they strongly influence the transport properties of lower mantle rocks. Perovskites are expected to be an important constituent of rocky planets larger than Mars and thus play a major role in modulating the evolution of terrestrial planets throughout the universe.

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Chen, Lung-Chien, Ching-Ho Tien, Yang-Cheng Jhou, and Wei-Cheng Lin. "Co-Solvent Controllable Engineering of MA0.5FA0.5Pb0.8Sn0.2I3 Lead–Tin Mixed Perovskites for Inverted Perovskite Solar Cells with Improved Stability." Energies 13, no. 10 (May 13, 2020): 2438. http://dx.doi.org/10.3390/en13102438.

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Use of a lead–tin mixed perovskite is generally considered an effective method to broaden the absorption wavelength of perovskite thin films. However, the preparation of lead–tin mixed perovskites is a major challenge due to the multivalent state of tin and stability in the atmosphere. This study attempted to replace the organic cation and metal elements of perovskites with a relatively thermal stable formamidinium (FA+) and a more environmentally friendly tin element. MA0.5FA0.5Pb0.8Sn0.2I3 lead–tin mixed perovskite thin films were prepared with the one-step spin-coating method. By adjusting the dimethylformamide (DMF):dimethyl sulfoxide (DMSO) concentration ratio of the lead–tin mixed perovskite precursor solution, the surface morphologies, crystallinity, and light-absorbing properties of the films were changed during synthesis to optimize the lead–tin mixed perovskite films as a light-absorbing layer of the inverted perovskite solar cells. The quality of the prepared lead–tin mixed perovskite film was the highest when the ratio of DMF:DMSO = 1:4. The power-conversion efficiency of the perovskite solar cell prepared with the film was 8.05%.

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Thrithamarassery Gangadharan, Deepak, and Dongling Ma. "Searching for stability at lower dimensions: current trends and future prospects of layered perovskite solar cells." Energy & Environmental Science 12, no. 10 (2019): 2860–89. http://dx.doi.org/10.1039/c9ee01591d.

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Two-dimensional perovskites are an attractive alternative to 3D perovskites for solar cell application as they directly address a critical issue of stability of 3D perovskite solar cells, while achieving similarly high power conversion efficiencies.

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Zhao, J., N. L. Ross, and R. J. Angel. "Estimation of polyhedral compressibilities and structural evolution of GdFeO3-type perovskites at high pressures." Acta Crystallographica Section B Structural Science 62, no. 3 (May 15, 2006): 431–39. http://dx.doi.org/10.1107/s0108768106009384.

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A new approach based on the bond-valence matching relation is developed to predict the detailed structural evolution of GdFeO3-type perovskites at high pressure from knowledge of the room-pressure structure and the high-pressure unit-cell parameters alone. The evolution of perovskite structures estimated in this way is in good agreement with the structure refinements available from high-pressure single-crystal diffraction measurements of a number of perovskites. The method is then extended to predict the structure of MgSiO3 perovskite at pressures for which no single-crystal structural data are available and the results are compared to ab initio quantum calculations of MgSiO3 perovskite up to 120 GPa.

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Eperon, Giles E., Giuseppe M. Paternò, Rebecca J. Sutton, Andrea Zampetti, Amir Abbas Haghighirad, Franco Cacialli, and Henry J. Snaith. "Inorganic caesium lead iodide perovskite solar cells." Journal of Materials Chemistry A 3, no. 39 (2015): 19688–95. http://dx.doi.org/10.1039/c5ta06398a.

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The vast majority of perovskite solar cell research has focused on organic–inorganic lead trihalide perovskites; herein, we present working inorganic CsPbI₃perovskite solar cells for the first time.

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Turren-Cruz, Silver-Hamill, Anders Hagfeldt, and Michael Saliba. "Methylammonium-free, high-performance, and stable perovskite solar cells on a planar architecture." Science 362, no. 6413 (October 11, 2018): 449–53. http://dx.doi.org/10.1126/science.aat3583.

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Currently, perovskite solar cells (PSCs) with high performances greater than 20% contain bromine (Br), causing a suboptimal bandgap, and the thermally unstable methylammonium (MA) molecule. Avoiding Br and especially MA can therefore result in more optimal bandgaps and stable perovskites. We show that inorganic cation tuning, using rubidium and cesium, enables highly crystalline formamidinium-based perovskites without Br or MA. On a conventional, planar device architecture, using polymeric interlayers at the electron- and hole-transporting interface, we demonstrate an efficiency of 20.35% (stabilized), one of the highest for MA-free perovskites, with a drastically improved stability reached without the stabilizing influence of mesoporous interlayers. The perovskite is not heated beyond 100°C. Going MA-free is a new direction for perovskites that are inherently stable and compatible with tandems or flexible substrates, which are the main routes commercializing PSCs.

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Fan, Ping, Huan-Xin Peng, Zhuang-Hao Zheng, Zi-Hang Chen, Shi-Jie Tan, Xing-Ye Chen, Yan-Di Luo, Zheng-Hua Su, Jing-Ting Luo, and Guang-Xing Liang. "Single-Source Vapor-Deposited Cs2AgBiBr6 Thin Films for Lead-Free Perovskite Solar Cells." Nanomaterials 9, no. 12 (December 11, 2019): 1760. http://dx.doi.org/10.3390/nano9121760.

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Lead-free double perovskites have been considered as a potential environmentally friendly photovoltaic material for substituting the hybrid lead halide perovskites due to their high stability and nontoxicity. Here, lead-free double perovskite Cs2AgBiBr6 films are initially fabricated by single-source evaporation deposition under high vacuum condition. X-ray diffraction and scanning electron microscopy characterization show that the high crystallinity, flat, and pinhole-free double perovskite Cs2AgBiBr6 films were obtained after post-annealing at 300 °C for 15 min. By changing the annealing temperature, annealing time, and film thickness, perovskite Cs2AgBiBr6 solar cells with planar heterojunction structure of FTO/TiO2/Cs2AgBiBr6/Spiro-OMeTAD/Ag achieve an encouraging power conversion efficiency of 0.70%. Our preliminary work opens a feasible approach for preparing high-quality double perovskite Cs2AgBiBr6 films wielding considerable potential for photovoltaic application.

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De Giorgi, Maria Luisa, Stefania Milanese, Argyro Klini, and Marco Anni. "Environment-Induced Reversible Modulation of Optical and Electronic Properties of Lead Halide Perovskites and Possible Applications to Sensor Development: A Review." Molecules 26, no. 3 (January 29, 2021): 705. http://dx.doi.org/10.3390/molecules26030705.

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Lead halide perovskites are currently widely investigated as active materials in photonic and optoelectronic devices. While the lack of long term stability actually limits their application to commercial devices, several experiments demonstrated that beyond the irreversible variation of the material properties due to degradation, several possibilities exist to reversibly modulate the perovskite characteristics by acting on the environmental conditions. These results clear the way to possible applications of lead halide perovskites to resistive and optical sensors. In this review we will describe the current state of the art of the comprehension of the environmental effects on the optical and electronic properties of lead halide perovskites, and of the exploitation of these results for the development of perovskite-based sensors.

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Gao, Zhan, Yifan Zheng, Guancheng Huang, Genjie Yang, Xinge Yu, and Junsheng Yu. "Additive Modulated Perovskite Microstructures for High Performance Photodetectors." Micromachines 11, no. 12 (December 10, 2020): 1090. http://dx.doi.org/10.3390/mi11121090.

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Organic-inorganic hybrid perovskites have been widely used as light sensitive components for high-efficient photodetectors due to their superior optoelectronic properties. However, the unwanted crystallographic defects of perovskites typically result in high dark current, and thus limit the performance of the device. Herein, we introduce a simple route of microstructures control in MAPbI3 perovskites that associates with introducing an additive of 3,3,4,4-benzophenonetetracarboxylic dianhydridean (BPTCD) for crystallization adjustment of the perovskite film. The BPTCD additive can facilitate the formation of high-quality perovskite film with a compact and nearly pinhole-free morphology. Through characterizing the molecular interactions, it was found that the carbonyl groups in BPTCD is the key reason that promoted the nucleation and crystallization of MAPbI3. As a result, we obtained high-efficient and stable perovskite photodetectors with low dark current of 9.98 × 10−8 A at −0.5 V, an on/off ratio value of 103, and a high detectivity exceeding 1012 Jones over the visible region.

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Deluque Toro, Crispulo Enrique, David Arsenio Landinez Tellez, Jairo Arbey Rodriguez Martinez, and Jairo Roa Rojas. "Estudio AB-Initio de las propiedades estructurales y electrónicas de la doble Perovskita Ba2InTaO6." Respuestas 18, no. 1 (January 1, 2013): 5–8. http://dx.doi.org/10.22463/0122820x.429.

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Los materiales de tipo Perovskita doble con fórmula genérica A2BB’O6 han sido ampliamente estudiados en los últimos años debido a su gran versatilidad, la cual permite la inclusión de iones de tipo alcalino térreo en los sitios A de la estructura y metales de transición en los sitios B y B’, dando origen a diversas propiedades físicas que redundan en múltiples aplicaciones industriales. En este trabajo estudiamos las propiedades estructurales y electrónicas del compuesto Ba2InTaO6, el cual es de particular interés ya que dichos sistemas podrían aplicarse en el desarrollo de resonadores dieléctricos y filtros para señal de microondas en teléfonos móviles y otros dispositivos inalámbricos, entre otras. Mediante modelamiento computacional ab-initio, basado en la Teoría de Funcional Densidad (DFT), y partiendo de la estructura de grupo espacial Fm-3m, evaluamos los parámetros de red, las energías de equilibrio y la ecuación de estado entre otras cantidades. La minimización de la energía en función del volumen permite la obtención de un parámetro de red de 15.861 Bohr. Los resultados de la Densidad de Estados Electrónicos (DOS) muestran que la doble Perovskita Ba2InTaO6 tiene un gap indirecto de ~ 4.25 eV.Palabras clave: Doble Perovskita, AB-Initio, estructura electrónica.Abstract The double Perovskites materials with the formula A2 BB’O6 has been studied thoroughly in the past years due to its versatility, which allow to include the alkaline earth ions in A sites and transition metals in B and B’sites, giving origin to several physical properties with various industrials applications. In this work the structural and electronic properties of Ba2 InTaO6 are studied, material that is particularly interesting due to its possible application to the development of dielectric resonators and microwave signal filters on mobile phones and other wireless devices. Using ab-initio computational model, based on the Density Funtional Theory (DFT), and starting from spacial group Fm-3m, we calculate lattice parameters, equilibrium energies and equations of state among other quantities. The energy minimization as a function of volume allows to obtain a attice constant of 15.861 Bohr. The results of electronic density of states (DOS) show that the double Perovskite Ba2 InTaO6 has an indirect gap of ~ 4.25 eV.Keywords: Double Perovskites, Ba2 InTaO6 , DFT, Electronic structure

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Journal articles on the topic 'Perovskitas'

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