Synthesis of Large‐Area Atomically Thin BiOI Crystals with Highly Sensitive and Controllable Photodetection

Compared to the most studied 2D elements and binary compounds, ternary layered compounds with more adjustable physical and chemical properties have exhibited potential applications in electronic and optoelectronic devices. Here, 2D ternary layered BiOI crystals are synthesized first with a domain size up to 100 µm via space‐confined chemical vapor deposition. The photodetectors based on the as‐grown BiOI nanosheets demonstrate high sensitivity to 473 nm light. The Ion/Ioff ratio and detectivity of BiOI photodetectors can reach up to 1 × 105 and 8.2 × 1011 Jones at 473 nm, respectively. Particularly, the contact and dark current of the photodetectors can be controlled by 254 nm ultraviolet light irradiation due to the introduction of oxygen vacancies. The facile synthesis of large‐area atomically thin BiOI and its controllable performance by ultraviolet light irradiation suggest that 2D BiOI crystal is a promising material for fundamental investigations and optoelectronic applications. Large‐area atomically thin BiOI crystals are obtained with a domain size over 100 µm via chemical vapor deposition. Photodetectors fabricated from ultrathin BiOI crystals show high sensitivity to 473 nm light. Also, oxygen vacancies can be introduced into BiOI crystals by 254 nm ultraviolet light irradiation.