Cs2NaYCl6:Er@KBr composite for applications of NIR LED with low working temperature

Owing to their environmental friendliness, structural tunability, and ability to emit self-trapped excitons, lead-free halide double perovskites (DPs) have demonstrated significant potential for applications in light-emitting diodes (LEDs) and photodetectors. However, their chemical and thermal stability is generally insufficient. These limitations hinder their practical application in LEDs, as these devices typically generate considerable heat under high operating currents and prolonged usage, particularly in the case of infrared LEDs. In this work, Er 3+ -doped double perovskites (Cs 2 NaYCl 6 and the Cs 2 NaYCl 6 @0.6 KBr composite) were synthesized via a hydrothermal method. The emission intensity of Cs 2 NaYCl 6 :2 % Er 3+ @0.6 KBr is five times greater than that of Cs 2 NaYCl 6 :2 % Er 3+ within the wavelength range of 1400–1600 nm. In the Cs 2 NaYCl 6 :Er 3+ @0.6 KBr composite, the surface defects of Cs 2 NaYCl 6 :Er 3+ were modified by the introduction of KBr, leading to an increase in the external quantum efficiency (EQE) of Cs 2 NaYCl 6 :Er 3+ from 9.5 % to 30.0 %. Under a 150 mA working current, the operating temperatures of the near-infrared (NIR) LED devices based on the Cs 2 NaYCl 6 :2 %Er 3+ and Cs 2 NaYCl 6 :2 %Er 3+ @0.6 KBr composite are 53.2 and 47.4 °C, respectively. After working for 2 h, the temperatures of the NIR LEDs based on Cs 2 NaYCl 6 :2 %Er 3+ and Cs 2 NaYCl 6 :2 %Er 3+ @0.6 KBr were 60.3 °C and 46.0 °C, respectively, under a 100 mA operating current.