Pseudohalogen Resurfaced CsPbBr<sub>3</sub> Nanocrystals for Bright, Efficient, and Stable Green-Light-Emitting Diodes.

Yang, Jun-Nan; Ma, Zhen-Yu; Luo, Jin-Da; Wang, Jing-Jing; Ye, Chunyin; Zhou, Yujie; Yin, Yi-Chen; Ru, Xue-Chen et al. · Nano Lett · 2023

basic_science · Level V

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Abstract

Lead halide perovskite nanocrystals (LHP NCs) are regarded as promising emitters for next-generation ultrahigh-definition displays due to their high color purity and wide color gamut. Recently, the external quantum efficiency (EQE) of LHP NC based light-emitting diodes (PNC LEDs) has been rapidly improved to a level required by practical applications. However, the poor operational stability of the device, caused by halide ion migration at the grain boundary of LHP NC thin films, remains a great challenge. Herein, we report a resurfacing strategy via pseudohalogen ions to mitigate detrimental halide ion migration, aiming to stabilize PNC LEDs. We employ a thiocyanate solution processed post-treatment method to efficiently resurface CsPbBr<sub>3</sub> NCs and demonstrate that the thiocyanate ions can effectively inhibit bromide ion migration in LHP NC thin films. Owing to thiocyanate resurfacing, we fabricated LEDs with a high EQE of 17.3%, a maximum brightness of 48000 cd m<sup>-2</sup>, and an excellent operation half-life time.