Synthesis of Thin Bi 9 O 7.5 S 6 Nanosheets for Improved Photodetection in a Wide Wavelength Range

Abstract

Bismuth-based compounds possess layered structures with a variety of stacking modes, endowing the compounds with diverse properties. As one type of bismuth oxysulfides, Bi 9O7.5S6 nanocrystals has great applications in photodetection; however, the responsivity of bulky Bi 9O7.5S6 is limited due to the poor charge separation. Herein, single-crystalline Bi 9O7.5S6 thin nanosheets are successfully synthesized by using a solvothermal method. The thickness of the obtained Bi 9O7.5S6 nanosheets is down to 15 nm and can be easily tuned by varying the reaction period. Moreover, the Bi 9O7.5S6 nanosheets show strong light absorption in the visible and near infrared range, making it a promising candidate in optoelectronics. As a demonstration, the thin Bi 9O7.5S6 nanosheets are used as active layer in an optoelectronic device, which exhibits sensitive photoelectric response to light in a wide range of 400-800 nm. The responsivity of the device reaches up to 1140 μA W−1, and the performance of the device is stable after long-period illumination. This work demonstrates a great potential of the thin Bi 9O7.5S6 nanosheets in optoelectronic devices, and these nanosheets may also be extended to various optoelectronic applications.