Application Of Novel Inorganic Compounds Materials On Counter Electrode In Dye-sensitized Solar Cells

Counter electrode (CE) is the important component of dye-sensitized solar cells (DSSCs); it fulfils electrocatalyzing reduction of oxidized electrolyte at the CE/electrolyte interface by transferring electrons flowing through the external circuit to the electrolyte. Although platinum (Pt) deposited conductive glass is the first choice as the CE, the high cost and energy-comsuming preparation definitely hinder the large-scale production of DSSCs. It is therefore of significance to develop cheap and efficient electrocatalysts to replace Pt. This thesis focuses on different types of inorganic compounds for use as electrocatalysts in DSSCs. The main results are summarized as follows:(1) We have successfully prepared NiS2@RGO nanocomposites via a facile in-situ hydrothermal reaction, and applied the composite as the novel CE material for DSSCs by a drop-casting technique. The electrochemical results revealed that the positive synergetic effect between NiS2 and RGO sheets on the reduction of I3-could greatly improve the catalytic activity, resulting in a significant enhancement of power conversion efficiency (PCE). The PCE for the DSSC with NiS2@RGO CE reached 8.55%, which is significantly higher than that (7.02%) for the DSSC with the NiS2 CE and that (3.14%) for the DSSC with the RGO CE. The nanocomposites are even better than the Pt electrode in solar cell performance, suggesting NiS2@RGO is a promising alternative to Pt electrode for DSSCs.(2) The graphene-like MoSe2 has been successfully prepared by a facile one-step hydrothermal reaction and is used as the CE material for DSSCs. Electrochemical results indicate that the MoSe2 CE exhibits good catalytic activity on the reduction of triiodide, and the MoSe2 CE based DSSC achieves PCE of 7.98%, which is close to that of the DSSC with Pt (8.22%).(3) Thin films of Coo.ssSe/RGO and Nio.ssSe/RGO are fabricated through self-assembly of selenides on the surface of GO nanosheets followed by in-situ reduction. It is revealed that the positive synergetic effect between metal selenides and RGO sheets on the reduction of I3- can greatly improve the catalytic activity, resulting in a significant enhancement of PCE. The PCE of DSSC with Co0.85Se/RGO and Ni0.85Se/RGO CE are 8.91% and 7.78%, respectively, which are much higher than that obtained from the single-component CE. This finding provides a new route to fabrication of cheap and efficient counter electrodes for flow-line production of DSSCs.