Kinetics Of Charge Transport In Dye-Sensitized Solar Cells And Diffusion Limitation Of Electrolytes

As a novel photovoltaic solar device, dye-sensitized solar cell (DSSC) is featuredas high efficiency, low cost, etc. Nowadays, it has been considered as an alternative toreplace conventional inorganic silicon solar cells. To get a further improvement inpower conversion efficiency, deeper investigations should be attached to the chargetransport as well as interfacial recombination.In this thesis, kinetics of recombination and charge transport in the electrolytephases of DSSCs was uncovered. We established the dynamical model describing thecharge transfer at TiO2/electrolyte interfaces., This model allows the electron lifetimedistribution, which features the interfacial recombination of a given energy state, to bedetermined experimentally. Accrding to experimental results, electron recombinationin DSSCs is non-ideal. This means electrons at the surface states are involved inrecombination reaction. Since significant diffusion limitation occurs in the DSSCsbased on cobalt-based electrolyte, it is key to formulate the quantitative relationbetween photocurrent loss and diffusion overpotential. In this thesis, a quasi-linearreaction-diffusion model was established to mimicking current density-voltage curvesand the distribution of diffusion overpotential of redox couples. Simultaneously,Fermi-level and electron density at the contact interfaces between FTO and TiO2filmwere attained. Based on the simulation results,,film thicknesses of TiO2were screenedto achieve the maximum power conversion efficieny. Such strategy paves the way tooptimize the architecture of DSSCs.