Molecular Bridging Strategy Enables High Performance and Stable Quasi-2D Perovskite Light-Emitting Devices

Quasi-two-dimensional (quasi-2D) Ruddlesden-Popper (RP) perovskites have attracted extraordinary attention due to their favorable energy funnel structures and outstanding optical performance. However, quasi-2D perovskites commonly contain the disordered mixture of phases, which results in low energy transfer between phases and subsequently limits the performance of the device. In this work, 4 '- (Aminomethyl)-biphenyl-3-carboxylic acid (4-ABCA) was introduced into PEA2(FAPbBr3)2PbBr4 (PEA = phenethylammonium) film. The experimental and theoretical investigations demonstrate that 4-ABCA can coordinate Pb2+ and Br- with its carboxyl and amion groups, respectively, which reconstructs the phase distribution of PEA2(FAPbBr3)2PbBr4 film, and simultaneously reduces the van der Waals gap, resulting in the efficient energy transfer of carriers. Finally, the external quantum efficiency (EQE) of 23.15% and the maximal brightness of 133560 cd/ m2 were achieved in the green perovskite light-emitting diodes (PeLEDs) based on quasi-2D film by adding 4-ABCA. Notably, it is the highest brightness for the pure green quasi-2D PeLEDs reported in the literature.