Enhancing Energy Transfer through Structure Reconstruction of Quasi-2D Perovskites for Highly Efficient Light-Emitting Diodes

Quasi-two-dimensional (quasi-2D) Ruddlesden–Popper (RP) perovskites, exemplified by BA₂Cs_n–1Pb_nBr_3n+1 (BA = butylammonium, n > 1), show promise as efficient emitters. However, their electroluminescence performance is limited by a significant energy loss during carrier transportation. Herein we use 2-methylthiophene-3-carboxylic acid (MeTCA), which forms robust hydrogen-bonding interactions with the spacer BA cations, to reconstruct the quasi-2D perovskite structure. This reconstruction enhances the energy transfer in perovskite films, thereby improving the light emission efficiency. Additionally, MeTCA reduces the defect density in RP perovskites by acting as an electron-rich Lewis base and eliminating uncoordinated Pb²⁺. Consequently, we achieve a photoluminescence quantum yield of up to 83.22% for the quasi-2D perovskite prepared by using the MeTCA additive strategy. Furthermore, we successfully fabricate high-efficiency quasi-2D perovskite light-emitting diodes with a maximum external quantum efficiency of 21.73% and a current efficiency of 70.30 cd A^–1.