Controllable Preparation And Catalytic Properties Of Transition Metal Chalcogenide Compounds

Dye-sensitized solar cells(DSSC) attract much attention because of the low-cost, easy fabrication and high power conversion efficiency(PCE). A DSSC is made up of counter electrode(CE), redox electrolytes, dye sensitzers and photoanode. In terms of the material for the CE, it should not only low cost, but combine high PCE and high stability as well. In this paper, a series of CEs(highly crystalline, small size, monodisperse Ni S nanocrystals(NCs); iron sulfide nanosheets(NSs) with expose high energy facets; copper tin zinc sulfide selenium) were fabricated based on transition-metal chalcogenide, both of which hold the merits of low cost and high PCE. And we systematically studied the relationship between the experimental parameters(e.g. the temperature of reaction, chemistry components) and the PCE, catalytic activity of the DSSCs. The main contents of this paper are as follows:1) We have controllable synthesis of highly crystalline, small size, monodisperse α-Ni S NCs. By controlling the temperature of reaction, the crystallinity of Ni S can be well tuned, followed by fabricating the CE with spray coating approach and used as CE materials for DSSCs. We studied the relationship between catalytic activity and PCE of DSSC. When the temperature of reaction reached to 300 ℃, we prepared Ni S-300 with high crystallinity, the DSSC based on it shows PCE of 7.33 %, which is comparable to that of Pt-based DSSCs(7.53 %). Because of highly crystalline, small sized Ni S NCs provided abundant catalytic reaction sites, which is favor for the reduction of I3-.2) The Fe S NSs with high-energy facets have been controllable synthesis. By controlling the temperature of reaction, iron sulfide NSs with different component(Fe S、Fe7S8) has been prepared. According to the performance test of the photoelectric measurement: Fe S NSs with high-energy(001) facet is used as CE materials for DSSCs, which achieves average PCEs of 8.88 %(the PCE of champion cells is 9.10 %) have been obtained. It is obvious higher than Fe7S8 NSs(8.06 %) and Pt-based(7.73 %) in parallel. Above result indicates that iron sulfide NSs with exposed high-energy facets have excellent catalytic activities.3) Controllable synthesis of monodisperse, small sized Cu2 Sn Zn S4 nanoparticals(NPs), Cu2 Sn Zn SxSe4-x was achieved by selenization, and then using doctor blade method to prepare CEs based on Cu2 Sn Zn S4 NPs and Cu2 Sn Zn SxSe4-x. Compare with Cu2 Sn Zn S4, the PCE of DSSCs based on Cu2 Sn Zn SxSe4-x CE have a significance improved, which is up to 7.13 %, it is closed to that of Pt-based DSSCs(7.62 %). It can be attributed to inset of Se in Cu2 Sn Zn S4 and change it crystal texture, catalytic activity has been improved.