Large‐Size Growth of Ultrathin SnS 2 Nanosheets and High Performance for Phototransistors

2D SnS 2 nanosheets have been attracting intensive attention as one potential candidate for the modern electronic and/or optoelectronic fields. However, the controllable large‐size growth of ultrathin SnS 2 nanosheets still remains a great challenge and the photodetectors based on SnS 2 nanosheets suffer from low responsivity, thus hindering their further applications so far. Herein, an improved chemical vapor deposition route is provided to synthesize large‐size SnS 2 nanosheets, the side length of which can surpass 150 μm. Then, ultrathin SnS 2 nanosheet‐based phototransistors are fabricated, which achieve high photoresponsivities up to 261 A W −1 (with a fast rising time of 20 ms and a falling time of 16 ms) in air and 722 A W −1 in vacuum, respectively. Furthermore, the effects of back‐gate voltage and air adsorbates on the optoelectronic properties of the SnS 2 nanosheet have been systematically investigated. In addition, a high‐performance flexible photodetector based on SnS 2 nanosheet is also fabricated with a high responsivity of 34.6 A W −1 .