Simple and Efficient Green-Light-Emitting Diodes Based on Thin Organolead Bromide Perovskite Films via Tuning Precursor Ratios and Postannealing Temperature.

Organometal halide perovskites (OHPs) are becoming a hot topic in the field of display and lighting. Unlike the strategy used for solar cells, that is, using several hundred nanometers thick OHP film for fully absorbing solar light to convert electricity, thin-film OHPs (<50 nm) are advantageous to restrain its self-absorption drawback and thus beneficial for preparing efficient light-emitting diodes (LEDs). Here we manipulate the excess molar ratio of MABr/PbBr2 precursors and the post-annealing temperature to obtain uniform thin-film OHPs and suppress the nonradiative defects. Using this simple process, high efficient green perovskite light-emitting diode (PeLED) was obtained, with a maximum luminance of 6124 cd m-2, current efficiency of 15.26 cd A-1, and external quantum efficiency of 3.38%, which is nearly three-fold enhancement with respect to the previous reported best PeLED based on thin perovskite films (<50 nm).