A Multifunctional "Halide-Equivalent" Anion Enabling Efficient CsPb(Br/I)3 Nanocrystals Pure-Red Light-Emitting Diodes with External Quantum Efficiency Exceeding 23%

作者：Zhang, Jibin; Zhang, Tiankai; Ma, Zhuangzhuang; Yuan, Fanglong^*; Zhou, Xin; Wang, Heyong; Liu, Zhe; Qing, Jian; Chen, Hongting; Li, Xinjian; Su, Shijian; Xie, Jianing; Shi, Zhifeng^*; Hou, Lintao^*; Shan, Chongxin

来源：Advanced Materials, 2023, 35(8).

DOI：10.1002/adma.202209002

• CsPb(Br
• I)(3) nanocrystals
• halide vacancies
• phase separation
• pure-red light-emitting diodes
• self-doping effect

Pure-red perovskite LEDs (PeLEDs) based on CsPb(Br/I)(3) nanocrystals (NCs) usually suffer from a compromise in emission efficiency and spectral stability on account of the surface halide vacancies-induced nonradiative recombination loss, halide phase segregation, and self-doping effect. Herein, a "halide-equivalent" anion of benzenesulfonate (BS-) is introduced into CsPb(Br/I)(3) NCs as multifunctional additive to simultaneously address the above challenging issues. Joint experiment-theory characterizations reveal that the BS- can not only passivate the uncoordinated Pb2+-related defects at the surface of NCs, but also increase the formation energy of halide vacancies. Moreover, because of the strong electron-withdrawing property of sulfonate group, electrons are expected to transfer from the CsPb(Br/I)(3) NC to BS- for reducing the self-doping effect and altering the n-type behavior of CsPb(Br/I)(3) NCs to near ambipolarity. Eventually, synergistic boost in device performance is achieved for pure-red PeLEDs with CIE coordinates of (0.70, 0.30) and a champion external quantum efficiency of 23.5%, which is one of the best value among the ever-reported red PeLEDs approaching to the Rec. 2020 red primary color. Moreover, the BS--modified PeLED exhibits negligible wavelength shift under different operating voltages. This strategy paves an efficient way for improving the efficiency and stability of pure-red PeLEDs.

• 单位
  郑州大学; i; 佛山科学技术学院