Gate-tunable dual-mode BiOI photodetector for precise object identification

The controllable growth of large-sized and high-quality semiconductor single crystals is an important guarantee for the realization of high-performance electronic and optoelectronic devices. Herein, we synthesized layered BiOI transparent single crystals through a tellurium-assisted chemical vapor transport strategy. Systematic investigation reveals that tellurium acts as a critical transport agent, directly modulating the crystallization dynamics and enabling the growth of high-quality 1-cm single crystals with precise size control. The layered BiOI crystals demonstrate excellent broadband (254–940 nm) photoresponse performance, achieving a remarkable responsivity of 123.7 A·W−1 and specific detectivity of 7.2 × 1013 Jones. Notably, the implementation of gate voltage regulation allows dynamic control of carrier transport mechanisms, achieving efficient regulation of the photoresponse of the device. This unique gate-tunable characteristic enables dual-mode operation in image recognition systems, simultaneously supporting both high-sensitivity detection and programmable contrast enhancement. The combination of scalable crystal growth and multifunctional optoelectronic properties positions BiOI as a promising candidate for next-generation intelligent photodetection technologies.