Interstitial Solid Solution Design Breaks the Property Ceiling: Cr <sup>3+</sup> Doped Near‐Infrared Phosphors with EQE Exceeding 50% and Zero‐Thermal‐Quenching Characteristics
Qianxi Pang, Yichao Wang, Ping Jin, Ge Zhu, Sai Xu, Jinsu Zhang, Xizhen Zhang, Yongze Cao, Hongquan Yu, Xiangping Li, Baojiu Chen
Abstract
Abstract Ultra‐efficient near‐infrared (NIR) phosphor‐converted light‐emitting diodes are essential for advancing biomedical imaging and nondestructive testing. However, existing Cr 3+ ‐doped phosphors encounter challenges such as low external quantum efficiency (EQE) and severe thermal quenching. Herein, we propose an innovative interstitial solid solution strategy by incorporating quadrivalent ions (e.g., Ge 4+ , Sn 4+ , Ti 4+ ) into Cr 3+ ‐activated β‐Ga 2 O 3 derivatives. The formation of interstitial oxygen ions during this process enhances structural rigidity and relaxes the spin selection rule of Cr 3+ by reducing the structural symmetry, as confirmed by first‐principles calculations and extended X‐ray absorption fine structure analysis. The optimized Ga 2–y Sc y O 3 :Cr 3+ , Ge 4+ phosphors, with emission tunable from 689 to 780nm, achieve ultra‐high EQEs exceeding 50% and exhibit nearly zero‐thermal‐quenching (ZTQ) characteristics. This is the first report of successfully developing NIR phosphors that simultaneously achieve EQE exceeding 50% and exhibit ZTQ properties. A representative as‐fabricated NIR pc‐LED device demonstrates superior performance, achieving an output power of 67.0 mW and a photoelectric conversion efficiency of 24.5% at 100 mA, surpassing state‐of‐the‐art devices and showcasing immense potential in bioimaging, night vision, and nondestructive testing. This work not only provides high‐performance NIR phosphors but also establishes a pioneering paradigm for designing advanced NIR phosphors via the interstitial solid solution strategy.