Trivalent Rare Earth Ion‐Doped Metal Halide Perovskite Near‐Infrared Semiconductors for High‐Performance Optoelectronic Devices

Abstract Given the extensive application of near‐infrared (NIR) emission, the quest for efficient and versatile NIR semiconductors have attracted tremendous attention. Leveraging trivalent rare earth (RE³⁺) ions doping, the integration of metal halide perovskites with RE³⁺ ions makes it easy to achieve NIR‐II emission (1000–1700 nm). However, although showing promise in bioimaging, optical communication, and night vision, enhancing NIR‐II emission intensity to promote further progress in real‐world applications remains a challenge. This review summarizes the recent advancements in RE³⁺ ion‐doped perovskite NIR semiconductors, and discusses what kind of properties are needed and how to achieve desired optical properties in various applications. The review starts with the synthesis methods for various material types with rich examples. Following this, the mechanisms of strategies for optimizing NIR luminescence performance are discussed in detail. Furthermore, the review highlights their multifunctional applications both as an electrically driven emitter in NIR light‐emitting diodes (LEDs) and as a down‐conversion emitter in photovoltaic devices (PVs) or phosphor‐converted LEDs (pc‐LEDs). Finally, insights on how to fill the gap between current research and future goals are provided. This review aims to provide a deeper understanding of RE³⁺ ion‐doped NIR light‐emitting perovskite materials, and to promote the exploration of efficient NIR emitters.