Broadband Near‐Infrared Garnet Phosphors with Near‐Unity Internal Quantum Efficiency

• Published in: Advanced optical materials Vol. 8; no. 12
• Main Authors: Basore, Endale T., Xiao, Wenge, Liu, Xiaofeng, Wu, Jianhong, Qiu, Jianrong
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.06.2020
• Subjects: Antisite defects; Broadband; Cr 3; garnets; Infrared radiation; Light emitting diodes; Light sources; Materials science; near‐infrared emission; Octahedrons; Optics; Phosphors; Portable equipment; Quantum efficiency; Solid solutions; Spectrometers; Substitutes; Thermal stability; Trivalent chromium
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202000296

Compact near‐infrared (NIR) light sources with broad emission band are essential to enable NIR spectroscopy compatible with portable devices, and phosphor‐converted light emitting diodes (pc‐LEDs) are efficient, low‐cost, and compact light sources. However, it is more challenging to develop highly efficient and thermally stable broadband NIR phosphors than conventional phosphors for white LEDs. Here, a series of solid solution phosphors with broadband NIR emission designed by cationic substitution in Cr3+ activated garnet Gd3Sc2Ga3O12 are reported. The internal quantum efficiency of Cr3+ emission can be significantly improved to nearly 100% via the substitution of ScO6 with smaller AlO6 octahedrons, which is attributed to the reduction of antisite defects. Moreover, the phosphor with optimized composition shows highly thermally stable emission, which renders the as‐fabricated pc‐LED with high‐power (750.8 mW) NIR emission covering the wavelength range of 700–1000 nm. The results could advance the development of NIR pc‐LEDs as high‐performance light sources for miniature NIR spectrometers. Broadband near‐infrared (NIR) phosphors with near‐unity internal quantum efficiency and high thermal stability are developed via the cation substitution of Sc3+ with smaller Al3+ to reduce the antisite defects of Cr3+ doped Gd3Sc2Ga3O12. Phosphor‐converted light emitting diodes (LEDs) with high‐power broadband NIR emission could serve as a compact light source for miniature NIR spectrometers.