Enhanced Efficiency, Broadened Excitation, and Tailored Er3+ Luminescence Triggered by Te4+ Codoping in Cs2naybcl6 Crystals for Multifunctional Applications

The quest for efficient and tunable luminescent materials has been at the forefront of research in the field of chemistry and materials science. This work delves into the investigation of the luminescence properties of Er3+ ions triggered by 1%Te4+ in the environmentally benign perovskite Cs2NaYbCl6 (CNYC) crystals, aiming to enhance their efficiency and tune the luminescence color. The ratio of the green (2H11/2, 4S3/2 - 4I15/2) to red (4F9/2 - 4I15/2) emissions of Er3+ can be freely tunable by varying the concentration of Er3+, and producing the defects induced by codoping Te4+. The calculations reveal that that the multiexcitonic excitations of Er3+ stem from f-f (4I15/2 – 4G11/2, 2H9/2) rather than d-f transitions. The broaden excitation, tuning of color, and enhancement of efficiency achieved in the luminescence perovskite crystals Cs2NaYbCl6:Te4+,Er3+ (CNYC:Te4+,Er3+) presents promising opportunities for the development of advanced optoelectronic devices with superior performance. Moreover, our investigation demonstrates the tunable luminescent response of CNYC:Er3+ to temperature variations, offering potential applications in temperature sensing.