부산대학교 도서관

Dye-sensitized solar cells (DSSCs) have been promised an alternative to conventional photovoltaic devices because of high-efficiency and effctive low-cost, Recently, many researchers have been studied and focused on the improving the photocurrent and photovoltage by developing new dye-sensitizer, suppressing the charge recombination, improving the interfacial contact and modifying the electrolyte components. The counter electrode of dye-sensitized soalr cells(DSSCs) is mostly prepared with expensive Pt materials as catalytic material. Carbon nanomaterials such as carbon nanotubes, carbon black are recently used as alternative materials owing to their high surface to volume ratio, high stability with low cost. A new member of carbon materials, called graphene comprised of a two-dimensional (2D) sheet of covalently bonded carbon atoms which is showing unique electronic property as well as strong catalytic activity. In this study, a new and effective counter electrode was designed by preparing the graphene thin film on fluorine doped tin oxide(FTO) substrate for the DSSCs. For graphene thin film, the graphene were firstly dispersed in the 1wt% solution of sodium dodecyl sulfate(SDS) and added polyvinylpyrrolidone(PVP) as wrapping agent. The dispersed graphene solution deposited on FTO substrate by simple casting method and annealed at 350℃ for 30min. The cyclic viltammograms (CV) measurements revealed that the prepared graphene counter electrode exhibited relatively high redox current density, indicating the higher electrocatalytic activity. for the redox reaction and increasing the reduction of the ions at counter electrode. The DSSCs fabricated with graphene counter electrode demonstrated a reasonably high overall conversion efficieny of 3.01% with high short current density (Jsc) of 11.16 mA/cm², open circuit voltage (Voc) of 0.726V and fill factor of 0.42, resulting from the enhanced morphological and electrochemical properties of graphene counter electrode by the use of PVP as wrapping agent. In the second part, a new and novel graphene-PEO composite electrolyte was prepared, characterized and applied as solid state electrolytes to fabricate solid-state DSSCs. Graphene-PEO composite electrolyte has shown significantly improved morphological and electrochemical properties, resulting in enhanced PV performance of DSSC.