SnS nanosheet films deposited via thermal evaporation: The effects of buffer layers on photovoltaic performance

Tin sulfide films were synthesized on different metal (Ag, Au) buffer layers by the deposition method of thermal evaporation. X-ray studies indicated an orthorhombic phase of SnS and Sn2S3 and hexagonal phase of SnS2 for all specimens. Microscopic investigations showed sheet morphologies with high density and uniform distribution across the surface of the specimens. It was also observed that Ag-buffer layer nanosheet films had the smallest thickness. The elemental analysis indicated the desired element on the surface of the films. Optical investigations confirmed that the SnS films on the buffer layer had strong emission bands which were red and near infrared (NIR) regions. Furthermore, Raman studies presented five Raman bands, and a shift to lower value of the wavenumber was observed by using buffer layers. The I-V and Mott-Schottky plots confirmed the p-type conductivity of nanosheet films. The solar cell devices fabricated from the films of SnS nanosheets exhibited a higher efficiency and power efficiency conversion (PEC) for the specimens that had buffer layers. The results of photosensitivity also demonstrated higher photosensitivity in red and NIR regions. And finally, photocurrent results displayed a higher photocurrent and lower raise and fall times for the films with buffer layers compared to the free buffer layer film. (C) 2016 Elsevier B.V. All rights reserved.