Achieving Efficient Light-Emitting Diodes by Controlling Phase Distribution of Quasi-2D Perovskites

Quasi-2D perovskite light-emitting diodes (PeLEDs) are promising candidates to realize superior luminescent. However, the poorly controlled phase distribution and surface defects hinder the improvement of the device's performance. Here, by introducing rubidium bromide (RbBr) to tune the crystallization kinetics of quasi-2D perovskites, more uniform phase distribution is achieved through the suppression of medium-n phases, resulting in narrower emission spectrum and more efficient energy transfer. Meanwhile, the defects are effectively passivated by the addition of RbBr. As a result, the photoluminescence quantum yield (PLQY) of quasi-2D perovskite films increases significantly from 45.6% to 81.3%, and the maximum external quantum efficiency (EQE) of PeLEDs reaches 18.92%. This finding provides a new insight into the phase distribution control of quasi-2D perovskites and the further improvement of PeLEDs.