Interstitial Li+ Occupancy Enabling Radiative/Nonradiative Transition Control toward Highly Efficient Cr3+-Based Near-Infrared Luminescence

Fanquan He; Enhai Song; Hui Chang; Yayun Zhou; Zhiguo Xia; Qinyuan Zhang

doi:10.1021/acsami.2c07495

Interstitial Li⁺ Occupancy Enabling Radiative/Nonradiative Transition Control toward Highly Efficient Cr³⁺-Based Near-Infrared Luminescence

ACS Appl Mater Interfaces. 2022 Jul 13;14(27):31035-31043. doi: 10.1021/acsami.2c07495. Epub 2022 Jul 2.

Authors

Fanquan He¹, Enhai Song^{1

2}, Hui Chang¹, Yayun Zhou¹, Zhiguo Xia^{1

3}, Qinyuan Zhang^{1

3}

Affiliations

¹ State Key Laboratory of Luminescent Materials and Devices and Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou 510641, P. R. China.
² MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials, Guangxi University, Nanning, Guangxi 530004, China.
³ School of Physics and Optoelectronics, South China University of Technology, Guangzhou 510641, China.

PMID: 35785991
DOI: 10.1021/acsami.2c07495

Abstract

Highly efficient and stable broadband near-infrared (NIR) emission phosphors are crucial for the construction of next-generation smart lighting sources; however, the discovery of target phosphors remains a great challenge. Benefiting from the interstitial Li⁺ occupancy-induced relatively large distorted octahedral environment for Cr³⁺ and suppressed nonradiative relaxation of the emission centers, an NIR emission fluoride phosphor Na₃GaF₆:Cr³⁺,Li⁺ peaking at 758 nm with a high internal quantum efficiency of 95.8% and an external quantum efficiency of 38.3% is demonstrated. Moreover, it exhibits a good thermal stability (84.9%@150 °C of the integrated emission intensity at 25 °C) and excellent moisture resistance as well. A high-power light-emitting diode (LED) with a record watt-level NIR output (974.12 mW) and a photoelectric conversion efficiency of 20.9% is demonstrated by combining Na₃GaF₆:Cr³⁺,Li⁺ and a blue InGaN chip, and a special information encryption/decryption technology suitable for rapid and long-distance identification of machines is further presented based on this device. This study not only advances the development of efficient NIR emission phosphors for broadband NIR LEDs but also for NIR-related emerging applications and devices.

Keywords: Cr3+ ions; LED; broadband NIR emission; high efficiency; watt-level output.