Tuning the Electronic Properties of 2D Bi ₂ O ₂ Se Nanosheets via Te Doping for Enhanced Infrared Photodetection

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Doping can effectively adjust the energy band structure of a semiconductor, thereby influencing its electrical and optical properties. In this study, density functional theory is employed to calculate the crystal structure, electronic configurations, energy bands, and optical properties of tellurium‐doped Bi 2 O 2 Se (Bi 2 O 2 Se 1‐x Te x ), demonstrating that Te substitution lowers the conduction band, reducing the bandgap. Then 2D Bi 2 O 2 Se 1‐x Te x nanosheets are synthesized via organic ion template‐guided solution growth method, with Te doping controlled by the Te/Se molar ratio. Optical spectroscopy confirmed that tellurium doping significantly modulates the electronic properties of Bi 2 O 2 Se. When the doping molar concentration is 30%, its bandgap decreases to 0.57 eV. Therefore, Bi 2 O 2 Se 1‐x Te x nanosheet‐based photodetector demonstrates obvious enhancement of the photoelectric response in the near‐infrared region. Notably, Bi 2 O 2 Se 0.7 Te 0.3 photodetector demonstrates broadband photosensitivity across 650–1550 nm, with high responsivity of 32.87 A W −1 and enhanced detectivity of 8.89 × 10 9 Jones at 1060 nm. The device also features a short response time of 16.8/11 µs at 1550 nm. Moreover, the photo‐response of the detector shows reliable working stability. Finally, the photodetector is utilized for single‐pixel imaging, showcasing its high‐contrast infrared light detection capability. These results indicate that Bi 2 O 2 Se 1‐x Te x is a promising material for high‐sensitivity infrared light detection applications.