Solution-processed highly bright and durable cesium lead halide perovskite light-emitting diodes

• Main Authors: Wei, Zhanhua, Perumal, Ajay, Su, Rui, Sushant, Shendre, Xing, Jun, Zhang, Qing, Tan, Swee Tiam, Demir, Hilmi Volkan, Xiong, Qihua
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2020
• Subjects: Science::Physics; Light-emitting Diodes (LEDs); CsPbBr3
• Online Access: https://hdl.handle.net/10356/140356
• Institution: Nanyang Technological University

Recently, CsPbBr3 perovskites have been emerging as very promising green emission materials for light-emitting diodes (LEDs) due to their high color purity, low cost and high photoluminescence quantum yield (PLQY). However, the corresponding LED performance is still low and far behind CH3NH3PbBr3; it is due to the lack of proper perovskite film preparation methods and interfacial engineering. Herein, we report highly bright and durable CsPbBr3-based LEDs fabricated using a one-step solution method. The precursor solution is prepared by simply dissolving CsPbBr3 powder and a CsBr additive in dimethyl sulfoxide (DMSO). We find that the CsBr additive not only significantly enhances the PLQY but also induces directional crystal growth into micro-plates, forming a smooth perovskite film for LEDs. LEDs employing such high quality films show a high luminance of 7276 cd m−2 and high color purity with a full width at half maximum of 18 nm. Furthermore, the as-fabricated LEDs reveal an outstanding ambient stability with a decent luminance output (>100 cd m−2, steady increase without any degradation trend) for at least 15 h under a constant driving current density (66.7 mA cm−2). And we propose two reasons for this unique luminance increasing behavior: (1) the CsPbBr3 perovskite is thermally stable and can survive from joule heat; and (2) on the other hand, the joule heating will induce interface or crystalline film annealing, reduce device resistance and then enhance the luminance output.