Efficient energy transfer in NaBaScSi2O7: Cr3+, Er3+ phosphor enabling simultaneously strong NIR-II/III emissions for diversified applications

Studies have shown that emissions in the NIR-II and NIR-III regions exhibit high tissue penetration, along with superior performance in biological and medical imaging applications. Therefore, developing NIR phosphors capable of simultaneously show emissions in both the NIR-II and NIR-III regions holds significant value. Herein, we developed a novel Cr 3+ /Er 3+ co-doped NaBaScSi 2 O 7 phosphor that demonstrates efficient dual-band emission in both NIR-II and NIR-III regions under visible light excitation, enabled by highly effective Cr 3+ →Er 3+ energy transfer. The energy transfer efficiencies calculated by the emission intensity and fluorescence lifetime are 65.3% and 47.4%, respectively, with the energy transfer mechanism dominated by dipole-dipole interaction. The prepared phosphor can be effectively excited by multiple excitation sources (378 nm, 492 nm, 808 nm, and 980 nm), generating distinct emission responses, highlighting its potential for anti-counterfeiting applications. Additionally, the distinct temperature-dependent optical properties of Cr 3+ and Er 3+ offer a viable approach for non-contact temperature detection, achieving a relative sensitivity of 0.8% K -1 and a temperature resolution of 0.126 K at 498 K. The NIR-II/III pc-LED fabricated by NaBaScSi 2 O 7 : 1%Cr 3+ , 0.2%Er 3+ demonstrates outstanding non-invasive imaging capability and accurate predictions for organic solvents. This study presents a strategy for developing phosphors capable of simultaneous NIR-II/III emission, and significantly advances their multifunctional applications in NIR optical thermometry and NIR pc-LED technologies.