Improving Green Perovskite Nanoplate Light-Emitting Diode Performance via Precision Passivation and Phase Distribution Management

In recent years, the realization of highly efficient perovskite light-emitting diodes (PeLEDs) based on two-dimensional perovskite nanoplates, featuring unique quantum-well structures and substantial exciton binding energies, has been a notable achievement. However, the perovskite emissive layer synthesized through solution processing has exhibited numerous defects, and the propensity for the formation of a wide-band gap low-dimensional phase has posed limitations on the advancement of PeLEDs. In this study, the small organic molecule trimorpholinophosphine oxide, containing PO bond, was employed for passivating the uncoordinated Pb²⁺ cations, while an antisolvent treatment using chlorobenzene was implemented to further optimize the phase distribution based on the PPA₂FA_n–1Pb_nBr_3n+1 perovskite film. This synergetic strategy effectively reduced the defect density and enhanced the energy transfer efficiency. Consequently, highly efficient PeLEDs were achieved, demonstrating a remarkable external quantum efficiency of 14.14% and a luminance of 17,196.7 cd/m², representing more than 5.06 and 1.77 times superior performance compared to the original devices, respectively. This study presents an approach for the defect passivation and phase distribution control in perovskites nanoplates.