Potassium Bromide Surface Passivation on CsPbI3-xBrx Nanocrystals for Efficient and Stable Pure Red Perovskite Light-Emitting Diodes

Jun-Nan Yang; Yang Song; Ji-Song Yao; Kun-Hua Wang; Jing-Jing Wang; Bai-Sheng Zhu; Ming-Ming Yao; Sami Ur Rahman; Yi-Feng Lan; Feng-Jia Fan; Hong-Bin Yao

doi:10.1021/jacs.9b11719

Potassium Bromide Surface Passivation on CsPbI_3-xBr_x Nanocrystals for Efficient and Stable Pure Red Perovskite Light-Emitting Diodes

J Am Chem Soc. 2020 Feb 12;142(6):2956-2967. doi: 10.1021/jacs.9b11719. Epub 2020 Jan 16.

Authors

Jun-Nan Yang^{1

2}, Yang Song¹, Ji-Song Yao^{1

2}, Kun-Hua Wang^{1

2}, Jing-Jing Wang^{1

2}, Bai-Sheng Zhu², Ming-Ming Yao^{1

2}, Sami Ur Rahman¹, Yi-Feng Lan¹, Feng-Jia Fan^{1

3

4}, Hong-Bin Yao^{1

2}

Affiliations

¹ Hefei National Laboratory for Physical Sciences at the Microscale , University of Science and Technology of China , Hefei , Anhui 230026 , China.
² Department of Applied Chemistry, Hefei Science Center of Chinese Academy of Sciences , University of Science and Technology of China , Hefei , Anhui 230026 , China.
³ CAS Key Laboratory of Microscale Magnetic Resonance , University of Science and Technology of China , Hefei , Anhui 230026 , China.
⁴ Synergetic Innovation Center of Quantum Information and Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China.

PMID: 31902206
DOI: 10.1021/jacs.9b11719

Abstract

All-inorganic lead halide perovskite nanocrystals (NCs) are potential candidates for fabricating high-performance light-emitting diodes (LEDs) owing to their precisely tunable bandgaps, high photoluminescence (PL) efficiency, and excellent color purities. However, the performance of pure red (630-640 nm) all-inorganic perovskite LEDs is still limited by the halide segregation-induced instability of the electroluminescence (EL) of mixed halide CsPbI_3-xBr_x NCs. Herein, we report an effective approach to improving the EL stability of pure red all-inorganic CsPbI_3-xBr_x NC-based LEDs via the passivation of potassium bromide on NCs. By adding potassium oleate to the reaction system, we obtained potassium bromide surface-passivated (KBr-passivated) CsPbI_3-xBr_x NCs with pure red PL emission and a photoluminescence quantum yield (PLQY) exceeding 90%. We determine that most potassium ions present on the surface of NCs bind with bromide ions and thus demonstrate that potassium bromide surface passivation of NCs can both improve the PL stability and inhibit the halide segregation of NCs. Using KBr-passivated CsPbI_3-xBr_x NCs as an emitting layer, we fabricated stable and pure red perovskite LEDs with emission at 637 nm, showing a maximum brightness of 2671 cd m^-2, maximum external quantum efficiency of 3.55%, and good EL stability. The proposed KBr-passivated NC strategy will open a new avenue for fabricating efficient, stable, and tunable pure color perovskite NC LEDs.