Ultrawide UV to NIR Emission in Double Perovskite Nanocrystals via the Self-Trapping State Engineering Strategy
Chao Wang, Ningjiu Zhao, Haoyue Zhang, Xiaofang Zhang, Xiaohuan Lin, Hao Liu, Fan Dang, Wei Zhang, Jing Sun, Peng Chen, Hailong Chen, Peigeng Han, Peng Li
Abstract
By codoping Ag + and Nd 3+ ions in Cs 2 NaBiCl 6 nanocrystals, we extend the photoluminescence range of inorganic double perovskite nanocrystals to the near-infrared (NIR) region for the first time. Specifically, the Ag + and Nd 3+ codoped Cs 2 NaBiCl 6 nanocrystals exhibit photoluminescence of f -electrons of Nd at 887, 1069, and 1350 nm. Meanwhile, transient fluorescence and femtosecond transient absorption spectroscopy studies show that Ag + doping induces self-trapped exciton (STE) states. Furthermore, the formation of STE helps construct suitable stepped energy levels, which improves the energy transfer efficiency and thus produces significant NIR photoluminescence. Based on the above results, AgNd-codoped double perovskite nanocrystals were assembled into a prototype photodetector. The photodetector exhibits a responsivity of 11.13 mA/W with detection rate D * of 2 × 10 10 Jones, which is a relatively high value among the lead-free double perovskite photodetectors. In addition, the photodetector has a response time of less than 40 ms due to the limitation of the instrument resolution. This work sheds light on the realization of efficient NIR photoluminescence and high-efficiency UV double perovskite nanocrystal photodetectors.