Efficient Inorganic Perovskite Light-Emitting Diodes by Inducing Grain Arrangement via a Multifunctional Interface.

Accumulating evidence shows that metal halide perovskite light-emitting diodes (PeLEDs) are well-described to show broad application prospects in lighting and display due to the wide color gamut and high color purity. However, it is still a great challenge to prepare high-quality all-inorganic PeLEDs by a solution method. For example, it is difficult to obtain all-inorganic perovskite films with good crystallinity and high grain orientation because of too fast and uncontrollable crystallization of all-inorganic perovskite films. Here, we demonstrated a multifunctional interface of formamide (FA)-doped PEDOT:PSS, which improved the crystallinity of all-inorganic perovskite films by inducing grain arrangement. As a result, a highly crystalline, ordered, and defect-passivated CsPbBr film was obtained by the multiple roles of FA, and the CsPbBr-based PeLED treated with FA achieved both high brightness and high efficiency: the peak external quantum efficiency (EQE) reaches 9.61%, and the maximum brightness is 185,000 cd/m. In addition, Tween 80, used as a passivator of perovskite films, reduced the defect states and suppressed ion migration. Under the synergistic effect of FA interface treatment and Tween 80 passivation treatment, efficient CsPbBr-based PeLEDs were obtained with an EQE of 15.02% and an operation lifetime of 182.5 min at an initial brightness of 1000 cd/m, which is among the best reported lifetimes under high brightness. Our study provides a simple and effective strategy for the realization of all-inorganic PeLEDs with high efficiency, high brightness, and ultralong operation lifetime.