Carbon-coated three-dimensional WS<inf>2</inf>film consisting of WO<inf>3</inf>@WS<inf>2</inf>core-shell blocks and layered WS<inf>2</inf>nanostructures as counter electrodes for efficient dye-sensitized solar cells

Abstract

© 2018 Elsevier Ltd The possibility of using solar energy for electricity generation has inspired intensive enthusiasm on the development of solar cell devices. This work reports the synthesis of a novel counter electrode (CE) composed of WO x @WS 2 @carbon core-shell film and compares its electrical and electrocatalytic performances with other two CEs of WO x /carbon film and conventional Pt in the dye-sensitized solar cells (DSSCs). The WO x @WS 2 @carbon CE was prepared by a sulfurization treatment of a mesoporous WO x /carbon film coated on fluorine-doped tin oxide (FTO) glass. The well-interconnected three-dimensional (3D) WS 2 structure with coated carbon film provides high electrocatalytic activity and fast reaction kinetics for the reduction of triiodide to iodide due to its sufficient active sites on 3D WS 2 framework containing surface edge-oriented nanosheets and the facile electron transfer and electrolyte diffusion via the continuously carbon layer. Photovoltaic performance tests indicate the DSSC device with the counter electrode of WO x @WS 2 @carbon core-shell achieved the power conversion efficiency (PCE) of 7.71% compared favourably with the values of 6.00% from WO x /carbon CE and 7.34% from conventional Pt CE. Such results vividly mirror that the developed WO x @WS 2 @carbon core-shell can replace the conventional Pt film, realizing Pt-free counter electrodes for DSSCs.