American Chemical Society
nn7b00608_si_001.pdf (3.72 MB)

In-Situ Formed Type I Nanocrystalline Perovskite Film for Highly Efficient Light-Emitting Diode

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journal contribution
posted on 2017-03-09, 00:00 authored by Jin-Wook Lee, Yung Ji Choi, June-Mo Yang, Sujin Ham, Sang Kyu Jeon, Jun Yeob Lee, Young-Hyun Song, Eun Kyung Ji, Dae-Ho Yoon, Seongrok Seo, Hyunjung Shin, Gil Sang Han, Hyun Suk Jung, Dongho Kim, Nam-Gyu Park
Excellent color purity with a tunable band gap renders organic–inorganic halide perovskite highly capable of performing as light-emitting diodes (LEDs). Perovskite nanocrystals show a photoluminescence quantum yield exceeding 90%, which, however, decreases to lower than 20% upon formation of a thin film. The limited photoluminescence quantum yield of a perovskite thin film has been a formidable obstacle for development of highly efficient perovskite LEDs. Here, we report a method for highly luminescent MAPbBr3 (MA = CH3NH3) nanocrystals formed in situ in a thin film based on nonstoichiometric adduct and solvent-vacuum drying approaches. Excess MABr with respect to PbBr2 in precursor solution plays a critical role in inhibiting crystal growth of MAPbBr3, thereby forming nanocrystals and creating type I band alignment with core MAPbBr3 by embedding MAPbBr3 nanocrystals in the unreacted wider band gap MABr. 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. Based on a highly luminescent nanocrystalline MAPbBr3 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.