Advancing the performance of photocathode dye-sensitized solar cells for their application in tandem solar cells

The aim of this thesis is to improve the performance of photocathode DSCs for their use in tandem DSCs. The scale of solar photovoltaic technology application is limited because of high costs. The research in the area of solar photovoltaic is focused on low cost technologies. Dye-sensitized solar cells (DSCs) are one of the attractive technologies for its projected low manufacturing costs. These solar cells are lagging behind in conversion efficiencies compared to other technologies available in the market. The efficiency of conventional DSCs can be improved with tandem solar cell architecture. In tandem solar cell approach, a photoanode DSC (n-DSC) is assembled with a photocathode DSC (p-DSC). Theoretically, efficiency improves due to the increase in the range of absorption spectra. However, the tandem DSC efficiencies are lagging behind the theoretical ones; because of underperforming photocathode DSCs. The p-DSC produces low photocurrents (5.4 mA/cm2) and has low efficiency (0.42 %) due to low open circuit voltages (350 mV). During this work, the application of microball structured NiO in p-DSC improved dye loading and p-DSC short circuit photocurrent (7.0 mA/cm2). The high efficiency p-DSCs using a cobalt ethylenediamine based electrolyte are reported in this thesis. Cobalt ethylenediamine electrolyte has favorable rest potential which helped to improve the p-DSC efficiency up to 1.3 %. A p-type semiconductor with high ionization potential (CuCrO2) improved VOC of p-DSC up to 740 mV. A transparent thiolate/disulfide based electrolyte has been studied and investigated as an alternative electrolyte in p-DSCs and tandem pn-DSCs.