Simultaneous Interfacial Modification and Crystallization Regulation for High-Performance Pure-Blue Quasi-2D Perovskite Light-Emitting Diodes

Quasi-2D perovskites have been recognized as promising candidates for light-emitting diode (PeLEDs) owing to their great optoelectronic properties and solution-processability. However, the disordered initial growth of the perovskites leads to phase disproportionation and defect formation in the perovskite film, which are detrimental to both stability and performance of the pure-blue PeLEDs. Herein, 4-methylbenzenesulfonate (EATsO) is designed as a buried interface to manage the crystallization process of quasi-2D perovskite films. The findings indicate that the strong interaction between EATsO and the precursors facilitates a well-ordered phase arrangement and reduces surface defects in quasi-2D perovskites, thereby enhancing the energy transfer within the perovskite films. Moreover, EATsO tunes the energy level alignment at the interface, which facilitates efficient hole injection and boosts radiative recombination in the PeLEDs. Benefiting from these improvements, the fabricated pure-blue PeLEDs (emitting at 468 nm) achieve a peak external quantum efficiency of 17.4% and a maximum luminance of 2346 cd m–2.