Near-Infrared Light-Emitting Diodes utilizing a Europium-Activated Calcium Oxide Phosphor with External Quantum Efficiency of up to 54.7.
basic_science · Level V
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- Record sourced from PubMed, PMID 35426472.
- Also identified by DOI 10.1002/adma.202201887.
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Abstract
Near-infrared (NIR) luminescence materials with broadband emissions are necessary for the development of light-emitting diodes (LEDs) based light sources. However, most known NIR-emitting materials are limited by their low external quantum efficiency. This work demonstrates how the photoluminescence quantum efficiency of europium-activated calcium oxide (CaO:Eu) NIR phosphor can be significantly improved and stabilized at operating temperatures of LEDs. A carbon paper wrapping technology is innovatively developed and used during the solid-state sintering to promote the reduction of Eu<sup>3+</sup> into Eu<sup>2+</sup> . In parallel, the oxygen vacancies in the CaO lattice are repaired utilizing GeO<sub>2</sub> decomposition. Through this process, a record-high external quantum efficiency of 54.7% at 740 nm is obtained with a thermal stability greatly improved from 57% to 90% at 125 °C. The as-fabricated NIR-LEDs reach record photoelectric efficiency (100 mA@23.4%) and output power (100 mA @ 319.5 mW). This discovery of high-performance phosphors will open new research avenues for broadband NIR LED light sources in a variety of photonics applications.