Cr<sup>3+</sup>↔Fe<sup>3+</sup> Energy Transfer Offset Enabling Anti‐Thermal Quenching Near‐Infrared Emission for Coded Wireless‐Communication Applications
Fanquan He, Enhai Song, Chuang Zhang, Hui Chang, Guoping Dong, Zhiguo Xia, Weichao Wang, Qinyuan Zhang
Abstract
Abstract Broadband near‐infrared (NIR) emission phosphors are crucial for the construction of next‐generation smart lighting sources; however, the thermal quenching (TQ) issue poses a significant challenge to their applications. In this study, anti‐TQ NIR emission is demonstrated in hexafluoride phosphors, using a facile Cr 3+ /Fe 3+ co‐doping strategy. Owing to the controlled forward resonance energy transfer (ET) from Cr 3+ to Fe 3+ and one‐phonon‐assisted back ET from Fe 3+ to Cr 3+ , the thermally enhanced broadband NIR luminescence is realised in series of fluoride such as Na 3 FeF 6 :Cr 3+ , Na 3 GaF 6 :Cr 3+ , Fe 3+ , K 2 NaScF 6 :Cr 3+ , Fe 3+ , etc. By varying the chemical composition of the phosphor, the anti‐TQ emission is achieved even upon raising the temperature to ≈423 K. The anti‐TQ luminescence mechanism is investigated, and the ET offset effect on luminescence TQ is demonstrated. More importantly, by combining these phosphors with blue InGaN chip, anti‐/zero‐TQ NIR light emitting diodes with a high photoelectric conversion efficiency even up to 19.13%@20 mA are further fabricated to realize the emerging coded optical wireless‐communication applications. These findings can initiate the exploration of NIR phosphors with anti‐TQ luminescence properties for advanced optoelectronic applications.