Characterization of tin(II) sulfide defects/vacancies and correlation with their photocurrent

Abstract

The presence of defects/vacancies in nanomaterials influences the electronic structure of materials, and thus, it is necessary to study the correlation between the optoelectronic properties of a nanomaterial and its defects/vacancies. Herein, we report a facile solvothermal route to synthesize three-dimensional (3D) SnS nanostructures formed by {131} faceted nanosheet assembly. The 3D SnS nanostructures were calcined at temperatures of 350, 400, and 450 °C and used as counter electrodes, before their photocurrent properties were investigated. First principle computation revealed the photocurrent properties depend on the defect/vacancy concentration within the samples. It is very interesting that characterization with positron annihilation spectrometry confirmed that the density of defects/vacancies increased with the calcination temperature, and a maximum photocurrent was realized after treatment at 400 °C. Further, the defect/vacancy density decreased when the calcination temperature reached 450 °C as the higher calcination temperature enlarged the mesopores and densified the pore walls, which led to a lower photocurrent value at 450 °C than at 400 °C.