Transition Metal Sulfides Prepared By Pulse Laser Deposition/Chemical Vapour Deposition And Their Photoelectrochemical Performance

Dye-sensitized solar cells(DSSCs)have specific advantages over other photovoltaic devices,such as simple fabrication procedures,environmental good plasticity,and friendliness.Although Pt is an effective CE for DSSCs,the expensiveness and scarcity of Pt have restricted further development of DSSCs.In order to reduce the cost and improve the performance,our research focuse on deveploping Pt-free CE in DSSCs systems.1)A series of transition metal sulfides MS2(M= Mo,W,Fe,Co,Ni)are prepared by a novel two-step reaction.The XRD results indicate no other phase transformation or impurities in the crystalline film.Cyclic voltammetry(CV),electrochemical impendence spectroscopy(EIS),and Tafel polarization measurements are apllied to investigate the catalytic activity of different MS2 CEs.The charge-ransfer resistance(Rct)of MoS2 and NiS2 are 8.88 and 8.95 ?·cm2,close to that of the Pt(6.35 ?·cm2),indicating the high activity for 13" reduction.Finally,TiO2-based DSSCs with different MS2 CEs show the high power conversion efficiency,which is reached the 90%of Pt CE.2)In this study,we prepare CoSe2 CEs under different pressure via a two-step deposition method.Cyclic voltammetry(CV),electrochemical impendence spectroscopy(EIS),and Tafel polarization measurements are apllied to investigate the catalytic activity of different CoSe2 CEs.The Rct of CoSe2 CEs deposited in 1,5,10 Pa are 1.10,2.48,1.76 ?·cm2,lower than the Pt CE(6.35 ?·cm2),indicating the higher catalytic activity than Pt CE.The TiO2-based DSSCs with an optimized CoSe2 CE exhibite an impressive 6.51%PCE,exceeding the Pt baesd DSSCs(5.22%).This finding indicate that the CoSe2 nanoctrystal film is promising CE for DSSCs.