Low-Dimensional Lead-Free Metal Halides for Efficient Electrically Driven Light-Emitting Diodes

Electrically driven light-emitting diodes (ED LEDs) based on 3D metal halide perovskites have seen remarkable advancements during the past decade. However, the highest-performing devices are largely based on lead-containing 3D perovskites, presenting two key challenges-toxicity and stability-that must be addressed for commercialization. Reducing structural dimensionality and incorporating non-lead metals present promising pathways to address these issues. Although research on ED LEDs based on low-dimensional, lead-free metal halides (LD LFMHs) is growing, their performance still significantly lags behind that of 3D lead halide perovskites. This review seeks to deliver a comprehensive overview of ED LEDs based on LD LFMHs, covering a brief history of their development, methods for material synthesis, luminescence mechanisms, and applications in electroluminescent devices. It also examines current challenges and proposes practical strategies to enhance device performance, with the goal of inspiring further progress in the field.