Continuous Ultra‐Broadband Near‐Infrared Sc2O3‐Based Nanophosphor Realized by Spectral Bridge of Cr3+‐Yb3+‐Cr4+ for Multiple Optical Applications

Abstract

AbstractCr3+‐activated near‐infrared (NIR) phosphors are one of the most influential candidates for the new generation of intelligent NIR phosphor‐converted light‐emitting diode (pc‐LED) light sources. For spectral analysis, the broader the spectrum, the more useful information it contains. Herein, ultra‐broadband Cr‐activated Sc2O3 nanophosphors, which exhibit NIR ultra‐broadband from 650 to 1600 nm, are developed by the sol–gel method. This ultra‐broadband emission originates from the presence of Cr3+ and Cr4+, two luminescent centers confirmed by diffuse reflection spectra, electron paramagnetic resonance, time‐resolved photoluminescence spectra, and temperature‐dependent emission spectra. The nanophosphor exhibits excellent temperature‐sensing performance with SA = 4.102% K−1 and SR = 1.855% K−1. Co‐doping Yb3+ into Sc2O3 nanophosphors builds the Cr3+‐Yb3+‐Cr4+ model to bridge the spectral gap located at 1000 nm, forming a continuous NIR ultra‐broadband spectrum ranging from 650 to 1600 nm for the first time. Moreover, the introduction of Yb3+ improves the thermal stability of nanophosphors from 29.49% to 50.65% at 150 °C. The NIR transmission spectra of water, ethanol, and peanut oil demonstrate that Sc2O3:Cr3+‐Yb3+‐Cr4+ NIR nanophosphors favor potential applications in spectral analysis. The construction of a Cr3+‐Yb3+‐Cr4+ spectral bridge for realizing NIR ultra‐broadband phosphors based on cheap blue LEDs provides novel and effective insights.