Synergistic mixed halide and additive strategy for efficient pure red quasi-2D perovskite light-emitting diodes†

Quasi-two-dimensional (quasi-2D) perovskites have demonstrated considerable potential in optoelectronic applications due to their excellent photophysical properties. However, achieving spectral stability in pure red emission (620–660 nm) via the mixed halide method remains a formidable challenge. Here, we address these issues by employing a mixed iodide–bromide strategy to achieve pure red emission, while simultaneously incorporating a 4,7,10-trioxa-1,13-tridecanediamine (TDA) additive to suppress spectral redshift and passivate defects. The lone pair electrons in the –COC groups of the TDA additive coordinate with unsaturated Pb²⁺, resulting in effective defect passivation. Meanwhile, the –NH₂ groups in the TDA additive form N–H⋯X hydrogen bonds with halogens (X = Br or I), effectively anchoring them and thereby inhibiting spectral redshift under operational voltage. Consequently, the photoluminescence quantum yield (PLQY) of TDA-modified perovskite film increases from 11.9% to 66.2%. The resulting perovskite light-emitting diodes (PeLEDs) exhibit pure red emission at 650 nm, with a maximum current efficiency of 6.76 cd A⁻¹ and a peak external quantum efficiency (EQE) of 12.39%, significantly outperforming the pristine devices. Our findings provide a promising strategy for the development of stable pure red PeLEDs.