Crystallization of Na2SrGe6O14:Cr3+,Yb3+ Glass Ceramics Enabling a Watt‐Level Output Power NIR‐I/NIR‐II Lighting Source

• Published in: Laser & photonics reviews Vol. 18; no. 1
• Main Authors: Wang, Taoze, Wang, Yuzhen, Chen, Weibin, Xia, Zhiguo
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.01.2024
• Subjects: Broadband; Critical components; Crystallization; Emission; Energy transfer; Glass ceramics; Illumination; Light emitting diodes; Lighting; lighting sources; luminescent glass ceramic; Near infrared radiation; near‐infrared; Phosphors; Photoelectricity; Quantum efficiency; Thermal stability; Trivalent chromium
• ISSN: 1863-8880; 1863-8899
• DOI: 10.1002/lpor.202300784

Near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) lighting sources are applied in non‐destructive examination and illumination supplements for night monitoring. As a critical component of NIR pc‐LED, NIR phosphors are required to possess a high external quantum efficiency (EQE), super thermal stability, and broadband emission to meet applications. Here, Na2SrGe6O14:Cr3+ (NSGO:Cr) glass ceramics (GC) bulk via highly crystallization from glass precursor is fabricated and demonstrates an ultrabroad emission band centered at 815 nm with a full width at half‐maximum (FWHM) of 214 nm and a high EQE of 49.2%. Moreover, Yb3+ co‐doping significantly enhances Cr3+ → Yb3+ energy transfer (ET) due to the stronger Yb3+: 2F7/2‐2F5/2 absorption. Benefiting from the ET process, the Cr/Yb co‐doped GC exhibits NIR‐I/II emission with improved thermal stability from 30.1% to 65.0%. Furthermore, an encapsulant‐free NIR GC‐converted LED (GCc‐LED) is prepared and exhibits 52.2 mW NIR output power with a high photoelectric conversion efficiency (PCE) of 19.4%. Under a large current of 600 mA, the NIR device exhibits a watt‐level output power of 922.4 mW with a PCE of 9.1%. Compared to conventional NIR powder phosphors, NSGO:Cr/Yb GC with high performance can open up an avenue for the fabrication of high power NIR lighting sources. Na2SrGe6O14:Cr3+ glass‐ceramic (GC) fully crystallized from glass shows a broadband near‐infrared (NIR) emission with a high external quantum yield of 49.2%. Cr3+ → Yb3+ energy transfer enables a broadened emission in the NIR‐I and NIR‐II range and enhanced thermal stability of 65.0%. The derived NIR GC‐converted LED exhibits watt‐level output power of 922.4 mW and shows potential application in night monitoring. .