Stabilizing electroluminescence color of blue perovskite LEDs via amine group doping

Voltage loading-induced change in the electroluminescence (EL) wavelength of mixed halide perovskite light-emitting diodes (PeLEDs), so-called color-shift, has become an inevitable phenomenon, which is seriously unfavorable to their applications in lighting and display. Here, we achieve color-stable blue PeLEDs via a hydrogen-bonded amine-group doping strategy. Selecting guanidine (GA) or formamidinium (FA) as amine-group (-NH2) doping source for CsPbBrxCl3-x quantum dots (QDs), experimental and theoretical results reveal that the strong N-H center dot center dot center dot X (X = Br/Cl) bonding can be produced between -NH2 dopants and Pb-X lattices, thereby increasing the migration barrier of halide anions. Resultantly, color-stable sky-blue devices were realized with emission peaks fixed at 490.5 (GA) and 492.5 (FA) nm without any obvious shift as the voltage increases, in sharp contrast devices without N-H center dot center dot center dot X producing a 15 nm red-shift from 487 to 502 nm. Not only that, maximum external quantum efficiency is improved to 3.02% and 4.14% from the initial 1.3%. This finding offers a convenient boulevard to achieve color-stable PeLEDs with high efficiency. (C) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

Color-stable blue PeLEDs were achieved through a hydrogen-bonded amine-group doping strategy, with emission peaks fixed at 490.5 (GA) and 492.5 (FA) nm without any obvious shift as the voltage increases. The maximum external quantum efficiency was also significantly improved.