Efficient and Stable Ytterbium‐doped CsPbCl ₃ Near‐Infrared Light‐Emitting Diodes via Additive‐Assisted Crystallization

Abstract Near‐infrared (NIR) luminescence technology plays a pivotal role in advanced applications, such as optical communication, biomedical imaging, and spectral analysis. Recently, the quantum‐cutting emission of Yb 3+ ‐doped lead halide perovskite, exhibiting a photoluminescence quantum yield exceeding 100%, has been extensively studied and applied in the field of optoelectronics. However, the development of Yb 3+ ‐doped CsPbCl 3 ‐based light‐emitting diodes faces a significant challenge in controlling the rapid crystallization of perovskite films. Herein, an additive‐assisted crystallization strategy is presented to control the formation process of Yb 3+ ‐doped CsPbCl 3 perovskite films, enabling the fabrication of high‐quality thin films. In situ photoluminescence measurements indicate that the introduction of additives effectively slows the reaction kinetics, resulting in slow crystal growth and optimizing film morphology. Additionally, the additives play a critical role in passivating defects, significantly enhancing the optical properties of the films. Consequently, the additive‐modified devices exhibit markedly improved electroluminescent performance, achieving stable spectral emission at 984 nm with an external quantum efficiency of 3.2% and an operating time of 940 s. This study not only provides a novel technological approach for advancing perovskite applications in NIR luminescence but also offers valuable insights for the future design and optimization of optoelectronic devices.