Comprehensive defect suppression in perovskite nanocrystals for high-efficiency light-emitting diodes

• Published in: Nature photonics Vol. 15; no. 2; pp. 148 - 155
• Main Authors: Kim, Young-Hoon, Kim, Sungjin, Kakekhani, Arvin, Park, Jinwoo, Park, Jaehyeok, Lee, Yong-Hee, Xu, Hengxing, Nagane, Satyawan, Wexler, Robert B., Kim, Dong-Hyeok, Jo, Seung Hyeon, Martínez-Sarti, Laura, Tan, Peng, Sadhanala, Aditya, Park, Gyeong-Su, Kim, Young-Woon, Hu, Bin, Bolink, Henk J., Yoo, Seunghyup, Friend, Richard H., Rappe, Andrew M., Lee, Tae-Woo
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2021; Nature Publishing Group
• Subjects: 119/118; 639/301/1019/1020/1091; 639/301/357/354; Applied and Technical Physics; Cadmium; Confinement; Crystals; Current carriers; Current efficiency; Doping; Efficiency; Electroluminescence; Electron recombination; Entropy; Light emitting diodes; Metal halides; Nanocrystals; Optics; Perovskites; Physics; Physics and Astronomy; Quantum efficiency; Quantum Physics; Radiative recombination; Recombination; Surface defects
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-020-00732-4

Electroluminescence efficiencies of metal halide perovskite nanocrystals (PNCs) are limited by a lack of material strategies that can both suppress the formation of defects and enhance the charge carrier confinement. Here we report a one-dopant alloying strategy that generates smaller, monodisperse colloidal particles (confining electrons and holes, and boosting radiative recombination) with fewer surface defects (reducing non-radiative recombination). Doping of guanidinium into formamidinium lead bromide PNCs yields limited bulk solubility while creating an entropy-stabilized phase in the PNCs and leading to smaller PNCs with more carrier confinement. The extra guanidinium segregates to the surface and stabilizes the undercoordinated sites. Furthermore, a surface-stabilizing 1,3,5-tris(bromomethyl)-2,4,6-triethylbenzene was applied as a bromide vacancy healing agent. The result is highly efficient PNC-based light-emitting diodes that have current efficiency of 108 cd A −1 (external quantum efficiency of 23.4%), which rises to 205 cd A −1 (external quantum efficiency of 45.5%) with a hemispherical lens. Guanidinium doping is shown to enhance the operation of perovskite nanocrystal light-emitting diodes.