[en] In the past decade, flat-panel displays have become ubiquitous due to the proliferation of modern electronic devices such as laptops, tablets, and smartphones. This has steered scientific efforts towards innovating electroluminescent materials that are energy efficient and possess excellent emission properties. As a result of extensive research, evaporated organic light emitting diodes emerged as a successful display technology and have since enjoyed significant market penetration. However, they have broad emission spectra and are also fairly expensive particularly for flexible displays. Thus, low-cost solution-processed light-emitting materials that exhibit colour pure electroluminescence are invaluable for next-generation display and lighting technologies. In this dissertation, novel light-emitting diodes based on perovskite semiconductors are presented. Some of their beneficial properties include bandgap tunability, balanced charge carrier mobilities, colour-pure emission with a full-width at half maximum of < 20 nm, solution processability, and low material cost. These attributes make them particularly attractive for low-cost light-emitting applications. By developing a device with suitable charge transport layers and by optimizing the perovskite deposition protocol, perovskite light-emitting diodes (PeLEDs) with luminance exceeding 17,000 cd/m2 with an external quantum efficiency of 3.9% were obtained. Further analysis shows that the key to better performance lies in fabricating thin and dense perovskite layers composed of tiny crystallites. Additionally, a novel gas-assisted perovskite thin-film deposition protocol was developed which is compatible with commercial roll-to-roll manufacturing techniques. Using this technique, large area devices with uniform emission were fabricated on a 230 cm2 substrate. While the efficiencies of PeLEDs have been gradually growing in the past four years, their operational lifetime needs to be addressed as it is relatively short. Here, the underlying degradation mechanisms in PeLEDs that limit their lifetime are elucidated. Decomposition of the organic cations in the perovskite layer seems to be the major degradation factor under bias. By replacing the organic cation with an inorganic cation their operational lifetime can be substantially improves. The insights provided in this dissertation are likely to catapult emerging PeLED technology further.

[es] Los dispositivos electrónicos modernos tales como televisores inteligentes, ordenadores portátiles, tabletas y teléfonos móviles requieren del uso de pantallas planas. Esto se logró en la última década usando pantallas de cristal líquido. Sin embargo, las proyecciones futuras llevan a usar pantallas flexibles y ligeras, un desafío importante para la tecnología convencional. Esto ha impulsado el desarrollo de materiales electroluminiscentes que son eficientes y tienen un contraste excelente. Como resultado de ello, nacieron los diodos orgánicos de emisión de luz (OLEDs), que han conseguido instalarse en el mercado. Sin embargo, esta tecnología es aún cara debido a la baja rentabilidad del proceso de fabricación de estos diodos. Es por ello que para la siguiente generación de paneles de pantalla plana y demás tecnologías de iluminación es muy importante poder disponer de materiales emisores que sean baratos, y que cuenten con una alta pureza de color. En esta tesis se estudian los diodos de emisión de luz (LEDs) basados en semiconductores de perovskitas. Estos LEDs se denominan diodos de emisión de luz de perovskita (PeLEDs). Aunque en la última década se ha logrado un progreso destacable en el campo de la fotovoltaica basada en materiales de perovskita, los PeLEDs todavía se encuentran en su fase inicial de desarrollo. Aún no se han llevado a cabo investigaciones exhaustivas sobre materiales y optimización de dispositivos, ni estudios fundamentales sobre el funcionamiento de los PeLEDs. Los siguientes capítulos se centrarán en abordar algunos de estos aspectos para contribuir a la mejora de las propiedades de los PeLEDs.