This article is cited by 137 publications. Based on a highly luminescent nanocrystalline MAPbBr 3 thin film, a highly efficient green LED with a maximum external quantum efficiency of 8.21% and a current efficiency of 34.46 cd/A was demonstrated.
A solvent-vacuum drying process was developed to preserve nanocrystals in the film, which realizes a fast photoluminescence lifetime of 3.9 ns along with negligible trapping processes. Excess MABr with respect to PbBr 2 in precursor solution plays a critical role in inhibiting crystal growth of MAPbBr 3, thereby forming nanocrystals and creating type I band alignment with core MAPbBr 3 by embedding MAPbBr 3 nanocrystals in the unreacted wider band gap MABr. Here, we report a method for highly luminescent MAPbBr 3 (MA = CH 3NH 3) nanocrystals formed in situ in a thin film based on nonstoichiometric adduct and solvent-vacuum drying approaches. The limited photoluminescence quantum yield of a perovskite thin film has been a formidable obstacle for development of highly efficient perovskite LEDs. Perovskite nanocrystals show a photoluminescence quantum yield exceeding 90%, which, however, decreases to lower than 20% upon formation of a thin film. Excellent color purity with a tunable band gap renders organic–inorganic halide perovskite highly capable of performing as light-emitting diodes (LEDs).