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

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.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)Accepted versio