Abstract：
Broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) hold promising potential as next-generation compact, portable, and intelligent NIR light sources. Nonetheless, the lack of high-performance broadband NIR phosphors with an emission peak beyond 900 nm has severely hindered the development and widespread application of NIR pc-LEDs. This study presents a strategy for precise control of energy-state coupling in spinel solid solutions composed of MgxZn1-xGa2O4 to tune the NIR emissions of Cr3+ activators. By combining crystal field engineering and heavy doping, the Cr3+-Cr3+ ion pair emission from the 4T2 state is unlocked, giving rise to unusual broadband NIR emission spanning 650 and 1400 nm with an emission maximum of 913 nm and a full width at half-maximum (fwhm) of 213 nm. Under an optimal Mg/Zn ratio of 4:1, the sample achieves record-breaking performance, including high internal and external quantum efficiency (IQE = 83.9% and EQE = 35.7%) and excellent thermal stability (I423 K/I298 K = 75.8%). Encapsulating the as-obtained phosphors into prototype pc-LEDs yields an overwhelming NIR output power of 124.2 mW at a driving current of 840 mA and a photoelectric conversion efficiency (PCE) of 10.5% at 30 mA, rendering high performance in NIR imaging applications.
摘要：
宽带近红外（NIR）磷光体转换发光二极管（pc-LED）作为下一代紧凑型，便携式，和智能近红外光源。尽管如此，缺乏发射峰超过900nm的高性能宽带NIR磷光体严重阻碍了NIRpc-LED的开发和广泛应用。这项研究提出了一种策略，用于精确控制由MgxZn1-xGa2O4组成的尖晶石固溶体中的能态耦合，以调节Cr3活化剂的NIR发射。通过结合晶体场工程和重掺杂，来自4T2状态的Cr3+-Cr3+离子对发射被解锁，产生不寻常的宽带NIR发射，跨越650和1400nm，发射最大值为913nm，半峰全宽（fwhm）为213nm。在4:1的最佳Mg/Zn比率下，样品达到了创纪录的性能，包括高的内部和外部量子效率（IQE=83.9％和EQE=35.7％）和出色的热稳定性（I423K/I298K=75.8％）。将获得的磷光体封装到原型pc-LED中，在840mA的驱动电流下产生124.2mW的压倒性NIR输出功率，在30mA下的光电转换效率（PCE）为10.5％，在近红外成像应用中呈现高性能。
