Enhanced Efficiency, Broadened Excitation, and Tailored Er³⁺ Luminescence Triggered by Te⁴⁺ Codoping in Cs₂NaYbCl₆...

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 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 (²H_11/2, ⁴S_3/2-⁴I_15/2) to red (⁴F_9/2-⁴I_15/2) 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 the multiexcitonic excitations of Er³⁺ stem from f-f (⁴I_15/2-⁴G_11/2, ²H_9/2) rather than d-f transitions. The broadened 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 luminescence response of CNYC:Er³⁺ to temperature variations, offering potential applications in temperature sensing.