Investigation Of Quasi-solid State Electrolyte And Carbon-based Counter-electrode Of Dye-sensitized Solar Cell

As a new generation of solar cells, dye-sensitized solar cell (DSC) has become a research focus because of the advantages in simple manufacture process, low cost and high efficiency in the past20years. The researchers all over the world firmly believe that DSC has a great potential in the future PV market. However, there still are some problems associated with performance limitations in long-term operation, such as the efficiency, cost, and stability. In this dissertation, the research work mainly focus on the quasi-solid state electrolyte, carbon-based counter-electrode, and large area DSC module.Two kinds of gel polymer electrolyte were fabricated with PEO/PVDF and PEO/P(VDF-HFP) as the framework materials and hybridized with TiO2nanoparticles. The dependence of the ionic conductivity, cell performance on the mass ratio of the polymers and the TiO2nanoparticles has been investigated. The DSCs facricated with PEO/PVDF/TiO2-and PEO/P(VDF-HFP)/TiO2-based gel polymer electrolyte have obtained the efficiency of5.52%and5.49%, respectively. The study has been confirmed that the resistivity, crystallinity, ionic conductivity of the gel polymer electrolyte can be improved by introducing the polymer with F ions into PEO matrix and hybriding with TiO2nanoparticles.Single-wall, double-wall and multi-wall carbon nanotubes (CNTs) have been investigated as alternatives for Pt in counter-electrodes (CEs) for DSC. The morphologies and the electrochemical properties of the CNTs-based CEs and the influence on the DSCs with these CEs have been disccused systematically. The cells produced with DWCNTs, SWCNTs or MWCNTs have overall conversion efficiencies of8.0%,7.6%and7.1%, respectively. After a600hours aging in dark at room temperature, the DSCs with CNTs-based CEs all showed an excellent stability. The results have been confirmed that the large surface area and superior chemical stability of the CNTs facilitated the electron-transfer kinetics at the interface between CE and electrolyte and yielded the lower transfer resistance, thereby improving the photovoltaic activity and stability.The graphene, a new2D nano material, has been investigated as a CE material for DSC. The graphene films revealed a unique3D network structure after annealing process. It can enhance charge transfer reaction within electrolyte by enlarging the effective reaction area and ensuring good adhesion between graphene films and FTO substrates. By optimizing the annealing process, the DSC fabricated with graphene-based CE achieved an overall energy conversion efficiency of6.81%in full sunlight.Upscaling DSCs is one of the important technologies to bring about the commercialization of DSCs. The fabrication techniques and procedures of10cm×10cm DSC modules in parallel-conneted and Z-type series-connected design have been developed. The parallel-connected DSC module yielded an efficiency of7.03%, and the Z-type series-connected one achieved8.08%. The CNTs-based CE was also utilized in parallel-connected DSC module and obtained an efficiency of5.51%.