Quasi-2D perovskites have emerged as a promising luminescent material for perovskite light-emitting diodes (Pe-LEDs). However, efficiency and stability are still obstacles to practical application due to numerous defects and inefficient energy transfer of perovskite films. Herein, functional phenethylammonium bromine-modified CsPbBr3 nanocrystals (PEA-CsPbBr3 NCs) are first introduced as multifunctional additive to simultaneously improve abovementioned problems. PEA-CsPbBr3 NCs not only serve as heteronuclear seeds and trigger growth, thus greatly reducing leakage current, but also deliver Cs+ and Br- to passivate the intrinsic defects inside film. More importantly, the PEA-CsPbBr3 construct a new carrier-transfer pathway from the small-n phase of the quasi-2D perovskite to the PEA-CsPbBr3 , which not only accelerates the energy-transfer process but also promotes radiation recombination of carriers due to stronger quantum confinement effect. Afterward, the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate/poly[9,9-dioctylfluoreneco-N-[4-(3-methylpropyl)]diphenylamine]:black phosphorus quantum dot double hole-transport layer is successfully constructed to enhance its carrier-injection and charge-transport abilities. Consequently, a champion external quantum efficiency of 25.32% and maximal brightness of 128 842 cd m-2 are achieved, which is the record efficiency of the quasi-2D Pe-LED with pure green emission at 530 nm. Moreover, an impressive 174 min lifetime is obtained at T50 , which is about five times longer than the control device.
Keywords: PEA-CsPbBr 3 NCs; defect passivation; energy-transfer process; quasi-2D perovskites; radiative recombination.
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