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

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.