Progress and Perspective in Low‐Dimensional Metal Halide Perovskites for Optoelectronic Applications

Organic–inorganic metal halide perovskites with three‐dimensional (3D) crystal structures have attracted tremendous attention due to their successful demonstrations in varying optoelectronic applications, particularly in photovoltaics (PV). Despite the rapid progress in achieving high performance in optoelectronic devices, the long‐term instability and lead toxicity in 3D perovskites are still two major challenges hindering their steps toward commercialization. To overcome these issues, a series of low‐dimensional perovskites and their derivatives are investigated, aiming at prolonging device lifetime and reducing toxicity. Herein, recent advances of low‐dimensional perovskites and their derivatives in PV with a focus on enhanced long‐term stability and reduced toxicity are reviewed. The fundamental understanding on their crystal structures and properties is presented. Beyond PV, the exploration of low‐dimensional perovskites for other promising optoelectronic applications is also summarized. In addition, the current challenges and future opportunities are discussed to provide a roadmap to the development of low‐dimensional perovskites.