Ultra-broadening near-infrared emission of Cr3+-activated pyroxene phosphors via chemical unit substitution and Yb3+ co-doping†
Abstract
Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) offer distinct advantages over traditional NIR light sources in the miniaturization of spectrometers. Nevertheless, the lack of highly efficient NIR phosphors with a large bandwidth hinders their practical applications. Herein, a novel Cr3+-doped (Ca1−xLix)(Mg1−xScx)Si2O6 phosphor with a broadened emission has been successfully developed by controlling the lattice disorder via [Li+–Sc3+] chemical unit substitution in CaMgSi2O6:Cr3+. Upon exciting the phosphor with 455 nm blue light, (Ca0.5Li0.5)(Mg0.5Sc0.5)Si2O6:4%Cr3+ exhibits notable NIR emission centered at approximately 847 nm, featuring a full width at half-maximum (FWHM) of 172 nm. The disordered occupation of Ca2+/Li+ and Mg2+/Sc3+ enhances the electron–phonon coupling effect, resulting in a broader emission of (Ca0.5Li0.5)(Mg0.5Sc0.5)Si2O6:Cr3+ compared with that of CaMgSi2O6:Cr3+. In order to further broaden the emission band, an energy transfer (ET) strategy is explored. By leveraging the ET process from Cr3+ to Yb3+, the FWHM of (Ca0.5Li0.5)(Mg0.5Sc0.5)Si2O6:4%Cr3+,0.4%Yb3+ is significantly increased up to 264 nm. The phosphor possesses a quantum yield of 46% and a thermal stability of 69% at 423 K. The NIR pc-LED utilizing the (Ca0.5Li0.5)(Mg0.5Sc0.5)Si2O6:Cr3+,Yb3+ phosphor yields an NIR optical power of 57.31 mW at a driving current of 300 mA, and achieves 10.01% photoelectric conversion efficiency at 25 mA, exhibiting promising potential for application in bio-imaging and food analysis.