Progress in all-inorganic heterometallic halide layered double perovskites

Abstract

The development of all-inorganic lead-free perovskite materials has attracted tremendous attention over the past few years due to their advantages in reduced toxicity, rich composition, unique crystal structures, and enhanced stability. All-inorganic lead-free heterometallic halide layered double perovskites (LDPs), also called quadruple perovskites, have emerged recently as a class of promising candidates for various optoelectronic applications, while providing ample opportunities to deepen our understanding of the composition–structure–property relationships. In this review, we focus on the recent progress in the material synthesis, composition tuning, crystal structure, phase transformation, and optoelectronic applications of all-inorganic heterometallic halide LDPs. Lastly, we identify current challenges and provide some prospects on future opportunities towards expanding LDPs from both fundamental research and broader application aspects.