Stabilizing electroluminescence color of blue perovskite LEDs via amine group doping
Fengjuan Zhang1, Jizhong Song1, Bo Cai1
1School of Materials Science and Engineering, MIIT Key Laboratory of Advanced Display Materials and Devices, Institute of Optoelectronics & Nanomaterials, Nanjing University of Science and Technology, Nanjing 210094, China.
Abstract:
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⋯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⋯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.
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