2,2′-Bipyridine-4,4′-dicarboxylic acid ligand engineered CsPbBr3 perovskite nanocrystals for enhanced photoluminescence quantum yield with stable display applications

Abstract

Cesium lead halide perovskite nanocrystals (PNCs) have emerged over the last decade as a promising candidate for optoelectronic devices, owing to their exceptional optical and color-tunable properties. Despite this, the instability of these materials and reduction in the photoluminescence (PL) properties with time prevents them from reaching their potential applications in the real world. The degradation in the PL properties of PNCs is due to surface defects caused by the removal of surface ligands. Herein, we have used a bidentate ligand, namely 2,2′-bipyridine-4,4′-dicarboxylic acid (BPY), to improve the optical properties of green-emitting CsPbBr₃ PNCs such as PL, and photoluminescence quantum yield (PLQY). The surface defects are reduced by the coordination of the carboxyl group of the bidentate BPY ligand with under-coordinated lead atoms. The PLQY of pristine CsPbBr₃ PNCs increased from 64 ± 2% to 88 ± 2% for BPY-CsPbBr₃ PNCs. In addition, a down-converted green light-emitting diode (LED) was fabricated by utilizing BPY-CsPbBr₃ PNCs, which shows its potential in display applications. Thus, our results will promote these inorganic PNCs in the commercial development of optoelectronic devices.