Growth of Large-Size SnS Thin Crystals Driven by Oriented Attachment and Applications to Gas Sensors and Photodetectors
Jun Wang, Gang Lian,* Zhenghao Xu, Chen Fu, Zhaojun Lin, Liyi Li, Qilong Wang, Deliang Cui,* and Ching-Ping Wong*

ACS Appl. Mater. Interfaces 2016, 8, 9545-9551

Abstract

Freestanding large-size SnS thin crystals are synthesized via two-dimensional oriented attachment (OA) growth of colloidal quantum dots (CQDs) in a novel high pressure solvothermal reaction. The SnS thin crystals present a uniform rectangular shape with a lateral size of 20-30 um and thickness of <10 nm. The evolution process demonstrates that a synergetic effect of pressure, aging time and organic ligands results in polycrystal-to-monocrystal formation and defect annihilation. Furthermore, gas sensor and photodetector devices, based on SnS thin single crystals, are also prepared. The sensing devices present high sensitivity, superior selectivity, low detection limit (≪100 ppb) and reversibility to NO₂ at room temperature. The fabricated photodetector devices exhibit a high responsivity of 2.04 × 10³ A W^-1 and high external quantum efficiency of ∼4.75×10⁵ % at 532 nm, which are much higher than most of the photodetector devices.