Ultrasmall SnS <sub>2</sub> quantum dot−based photodetectors with high responsivity and detectivity
Yi Ren, Hua An, Weiguan Zhang, Songrui Wei, Chenyang Xing, Zhengchun Peng
Abstract
Abstract Quantum dots (QDs) often exhibit unique behaviors because the reduction in lateral size leads to stronger quantum confinement effects and a higher surface‐to‐volume ratio in comparison with larger two‐dimensional nanosheets. However, the preparation of homogeneous QDs remains a longstanding challenge. This work reports the preparation of high‐yield and ultrasmall tin disulfide (SnS 2 ) QDs by combining top–down and bottom–up approaches. The as‐prepared SnS 2 QDs have a uniform lateral size of 3.17 ± 0.62 nm and a thicknesses 2.39 ± 0.88 nm. A series of self‐powered photoelectrochemical‐type photodetectors (PDs) utilizing the SnS 2 QDs as photoelectrodes are also constructed. Taking advantage of the tunable bandgaps and high carrier mobility of the SnS 2 , our PDs achieve a high photocurrent density of 16.38 μA cm −2 and a photoresponsivity of 0.86 mA W −1 , and good long‐term cycling stability. More importantly, the device can display obvious photoresponse, even at zero bias voltage (max), and greater weak‐light sensitivity than previously reported SnS 2 ‐based PDs. Density functional theory calculation and optical absorption were employed to reveal the working mechanism of the SnS 2 QDs‐based PDs. This study highlights the prospective applications of ultrasmall SnS 2 QDs and provides a new route towards future design of QDs‐based optoelectronic devices.