Enhanced Efficiency, Broadened Excitation, and Tailored Er 3+ Luminescence Triggered by Te 4+ Codoping in Cs 2 NaYbCl 6 Crystals for Multifunctional Applications.

The quest for efficient and tunable luminescent materials has been at the forefront of research in the fields of chemistry and materials science. This work delves into the investigation of the luminescence properties of Er 3+ ions triggered by 1% Te 4+ in the environmentally benign perovskite Cs 2 NaYbCl 6 (CNYC) crystals, aiming to enhance their efficiency and tune the luminescence color. The ratio of the green ( 2 H 11/2 , 4 S 3/2 - 4 I 15/2 ) to red ( 4 F 9/2 - 4 I 15/2 ) emissions of Er 3+ can be freely tunable by varying the concentration of Er 3+ and producing the defects induced by codoping Te 4+ . The calculations reveal that the multiexcitonic excitations of Er 3+ stem from f-f ( 4 I 15/2 - 4 G 11/2 , 2 H 9/2 ) rather than d-f transitions. The broadened excitation, tuning of color, and enhancement of efficiency achieved in the luminescence perovskite crystals Cs 2 NaYbCl 6 :Te 4+ , Er 3+ (CNYC:Te 4+ ,Er 3+ ) presents promising opportunities for the development of advanced optoelectronic devices with superior performance. Moreover, our investigation demonstrates the tunable luminescence response of CNYC:Er 3+ to temperature variations, offering potential applications in temperature sensing.