Organic Ion Template‐Guided Solution Growth of Ultrathin Bismuth Oxyselenide with Tunable Electronic Properties for Optoelectronic Applications

Abstract 2D Bi₂O₂Se has recently attracted widespread research interest due to its high electron mobility and good air stability with tunable bandgap. However, the direct and controllable growth of large‐size, high‐quality ultrathin Bi₂O₂Se with tunable electronic properties remains a great challenge. Here, an organic ion template‐guided solution growth method, is developed using water as a solvent to efficiently obtain high‐quality 2D Bi₂O₂Se. Significantly, the thicknesses and morphologies of 2D Bi₂O_xSe with various oxygen deficiencies; are also achieved. Optical spectroscopic results indicate that oxygen defects can dramatically tune the electronic properties of Bi₂O₂Se, such as work function, band gap, and energy‐band positions. As a result, the optimized Bi₂O₂Se devices exhibit a high photoresponsivity of 842.91 A W⁻¹, photo‐detectivity of 8.18 × 10¹² Jones under 532 nm laser, and electron mobility of 334.7 cm² V⁻¹ s⁻¹. This work proposes a new green solution method to synthesize large‐sized, high‐quality Bi₂O₂Se with tunable electronic structures that can be extended for various applications and provides a new possibility of transfer‐free large‐scale device manufacturing.