NIR II-responsive core–shell La2O2S:Er3+@La2O2S nanoparticles towards 1.5 μm photodetection

Abstract

Rare-earth doped oxysulfides have gained considerable attention as a luminescence host material owing to its good chemical stability and high efficiency. In this study, Er³⁺-sensitized La₂O₂S nanoparticles are prepared by the high-temperature co-precipitation method. La₂O₂S:2%Er³⁺ is selected to construct La₂O₂S:Er³⁺@La₂O₂S core/shell structures through epitaxial growth, and the luminescence properties are studied. The surface defects of La₂O₂S:Er³⁺ are repaired by the inert protective shell, and the luminescence intensity of the core/shell nanocrystals is increased by 9.6 times. Finally, MAPbI₃ is spin-coated over the La₂O₂S:Er³⁺@La₂O₂S film to construct narrow band near-infrared photodetectors. Under 1550 nm excitation, the response rate is 23 mA W⁻¹, detection rate is 2.57 × 10⁸ Jones, and response time is 220 ms.