Perovskite light-emitting diodes (PeLEDs) still faces the challenges such as poor film morphol. and inefficient energy transfer from the small-n phase to the large-n phase leading to rapid efficiency degradation and instability in high temperatureTo address these issues, herein, chlormezanone was employed to modify the perovskite film.Combined beneficial points were obtained including improved film morphol., reduced luminescence quenching, enhanced phase distribution and energy transfer by suppressing small-n phases, and defect mitigation at grain boundaries/interfaces via passivation groups (C = O, S = O).Consequently, the fabricated sky-blue PeLEDs delivered an external quantum efficiency of 10.14 % and an operating lifetime (T50) of 23.1 min, which was twice as long as the control device.This developed strategy significantly enhanced the stability while maintain excellent efficiency, providing a solid foundation for future investigation.