High-efficiency and thermally stable Cr3+-Doped CaCd2Ga2Ge3O12 phosphor for broadband near-infrared LED applications

Abstract

Advances in science and technology are increasing the use of intelligent near-infrared light sources in daily life, driven by their applications in food monitoring and analysis, night-vision imaging, and biology. This has spurred interest in new broadband near-infrared luminescent materials; however, poor thermal stability limits their application. Herein, This article provides new insights into near-infrared phosphors with improved thermal stability. A novel Cr³⁺ doped near-infrared phosphor with improved thermal stability has been reported. Under excitation of 450 nm light, CaCd₂Ga_2-xGe₃O₁₂:Cr³⁺ exhibits broadband emission originating from ⁴T₂–⁴A₂ from 640 nm to 1010 nm which reached maximum peak at 740 nm with a full width at half-maximum (FWHM) from 158 to 192 nm, driving from two Cr³⁺centers in CaCd₂Ga_2-xGe₃O₁₂:x%Cr³⁺ (x = 0.01, 0.02, 0.03, 0.04, 0.05), as evidenced by spectra and decay curves.The optimal internal quantum efficiency of the phosphor is 19.1 %, and the internal quantum efficiency is 69.0 %. At 373 K, it can maintain a luminescence intensity of about 90 %, and even at 423 K, it can maintain a luminescence intensity of no less than 80 % compared to room temperature. Combining CaCd₂Ga₂Ge₃O₁₂:Cr³⁺ with a 460 nm blue InGaN chip, bringing about a device that shows a near-infrared output power of 35.84 mW when operating with current 300 mA. A high thermal stability near-infrared pc-LED was manufactured and demonstrated for rapid imaging and night vision of fruits.