Synthesis of Thin Bi9O7.5S6 Nanosheets for Improved Photodetection in a Wide Wavelength Range

Graphical Single-crystalline Bi 9 O 7.5 S 6 thin nanosheets were successfully synthesized by using a solvothermal method. The thin Bi 9 O 7.5 S 6 nanosheets are used as active layer in an optoelectronic device, which exhibits a sensitive photoelectric response to light in a wide range of 400–800 nm. 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 9 O 7.5 S 6 nanocrystals has great applications in photodetection; however, the responsivity of bulky Bi 9 O 7.5 S 6 is limited due to the poor charge separation. Herein, single-crystalline Bi 9 O 7.5 S 6 thin nanosheets are successfully synthesized by using a solvothermal method. The thickness of the obtained Bi 9 O 7.5 S 6 nanosheets is down to 15 nm and can be easily tuned by varying the reaction period. Moreover, the Bi 9 O 7.5 S 6 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 9 O 7.5 S 6 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 9 O 7.5 S 6 nanosheets in optoelectronic devices, and these nanosheets may also be extended to various optoelectronic applications.