Surface Defect Recovery in Perovskite Nanocrystals with Excess Halide for Core–Shell Structure
Dong Hyeon Lee, Woo Hyeon Jeong, Seokhyun Choung, Ji Won Jang, Gyudong Lee, Hochan Song, Sang‐Hun Han, Gyeong Eun Seok, Ji-Hoon Kim, Myeonggeun Han, Jeong Woo Han, Hyosung Choi, Jongmin Choi, Bo Ram Lee, Yong‐Young Noh
Abstract
We present a method to synthesize stable and uniform high-quality perovskite nanocrystals (PNCs) by using excess halide to recover surface defects in CsPbBr 3 /ZnS core/shell nanocrystals. Use of N -bromosuccinimide as a halide donor recovered surface halide vacancies of bare CsPbBr 3 PNCs during the growth of the ZnS shell, as confirmed by DFT calculations. This approach achieves a high photoluminescence quantum yield of nearly 1, and significantly increases the stability of PNCs under adverse conditions such as high humidity and elevated temperature. CsPbBr 3 /ZnS PNC light-emitting diodes demonstrated outstanding luminous characteristics, with a remarkable external quantum efficiency of 12.77% and a maximum luminance of 1449 cd m –2 at 517 nm. These characteristics of the PNCs will have a wide variety of applications and will help enable development of highly efficient optoelectronic devices.