Enhancing violet perovskite light-emitting diode performance via adjusting carrier effective mass

Violet-light emitters serve critical functions across diverse domains, spanning biology, photopolymerization processes, and anti-counterfeiting solutions. In perovskite materials, the partial substitution of Pb²⁺ with Sr²⁺ at the B-site enables the preparation of perovskite films with continuously tunable emission from green to violet. These films exhibit excellent photoluminescence quantum yields, highlighting the potential of Sr-based metal halide perovskites for violet-emitting applications. However, excessive introduction of Sr²⁺ increases the carrier effective mass, resulting in a significant decline in carrier mobility. Herein, we demonstrate that K⁺ doping optimizes the carrier effective mass, which contributes to a notable enhancement in carrier mobility. Density functional theory (DFT) calculations indicate that the carrier mobility in K⁺-modified perovskite is approximately 1.5 times that of the pristine perovskite. Moreover, the disparity between electron and hole mobilities is reduced, indicating a more balanced trend in charge transport properties. The K⁺-modified device exhibited a stable emission peak at 420 nm and achieved a maximum external quantum efficiency (EQE) of 0.35%, representing high performance among violet perovskite light-emitting diode (PeLEDs). This work presents a facile strategy for fabricating high-performance violet PeLEDs with enhanced efficiency and stability.