Perovskite light-emitting diodes

University of Oulu 2020-12-15

The usage of artificial lighting and displays is increasing all the time. Energy efficient and affordable light-emitting materials are being developed widely. Light-emitting diodes (LEDs) are energy efficient, and LED technology and displays based on LEDs have developed greatly in the recent years. In the year 2014, the first research article related to a perovskite LED (PeLED) that is functional in room temperature was released. The light-emitting material in PeLED has ABX3 stoichiometry and perovskite structure. The most common A-cations used in perovskites in PeLEDs are methylammonium, formamidinium and cesium (Cs+). The most common B-cation is lead (Pb2+) and X-anion is a halide or a mixture of halides. Lead halide perovskites are interesting light-emitting materials, since they can be readily solution processed with inexpensive methods. The emission of lead halide perovskites can be tuned across the whole visible spectrum by changing the composition, and the emission colors are bright due to narrow emission. There are multiple challenges in PeLED development. Especially the efficiency of blue PeLEDs needs to be improved. Furthermore, there are challenges related to health and stability. The perovskite used in PeLEDs contains lead, which is poisonous, and perovskites are often solution processed from toxic solvents such as dimethylformamide. The biggest challenges in perovskite stability are sensitivity to moisture, oxygen, illumination and heat. Moreover, the stability is affected by mechanical stress, reactions caused by electric bias and reactions between materials used in PeLEDs. In this thesis, the most common perovskite materials, PeLED architectures, and their characterizations are introduced. Challenges in PeLED development are discussed, especially stability. Perovskite stability can be increased by e.g. perovskite substitution, additives, morphology control and optimization of PeLED structure.Tiivistelmä. Keinovalaistuksen ja näyttöjen määrä

Kemian maisteriohjelma; info:eu-repo/semantics/masterThesis; info:eu-repo/semantics/publishedVersion

Open access content. Open access content
info:eu-repo/semantics/openAccess
© Antti Nurmesjärvi, 2020

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