Controlled Synthesis of Bi₂O₂Te Nanosheets for High-Performance Broadband Photodetectors

Broadband photodetectors, covering visible to infrared spectra, are widely used in communications, imaging, military, and the medical fields. Recently, low-dimensional material-based photodetectors have gained significant attention. Low-dimensional Bi2O2Se has been extensively studied for its excellent air stability and optical properties. Similarly, Bi2O2Te shares these advantages and has a narrower band gap of 0.13 eV. However, research on Bi2O2Te remains limited, likely due to its challenging synthesis conditions, which have impeded the study of its optoelectronic properties. In this study, we successfully synthesized large-scale (235 μm, the largest reported to date) Bi2O2Te nanosheets using an upside-down growth chemical vapor deposition method. Furthermore, the fabricated Bi2O2Te photodetector exhibits broadband photoresponse (520 nm-2 μm), an ultrahigh responsivity of 3679 A W–1, an impressive detectivity of 8.91 × 1011 cm Hz1/2 W–1, and a fast response time (τrise/τdecay ≈ 32/92 μs), demonstrating its potential for applications in high-performance photodetectors. More importantly, this work provides a significant contribution to the further investigation of Bi2O2Te.