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Abstract: This work entails a method to improve the performance of dye-sensitized nanocrystalline TiO2 solar cells by adding surface passivating elements to the electrolyte. The presence of either CO2, Li2CO3 or K2CO3 in electrolyte increases both the photocurrent and the photovoltage, resulting in higher overall conversion efficiency of these solar cells. The additives are used to form a passivation layer of lithium carbonate on the dye free surface of the TiO2 nanoparticles and the conductive substrate. This layer suppresses the rate of the main recombination reaction between the photoinjected electrons and the oxidized ions in the electrolyte solution. While blocking part of the recombination, the lithium carbonate layer allows motion of the Li+ ions towards the TiO2 surface for charge screening. Consequently using this simple treatment, the conversion efficiency of dye-sensitized solar cell most improved by 17.2% (from 6.4% to 7.5%). [Copyright &y& Elsevier]

Abstract: 4-Ethoxy-2-methylpyridine (EOP), as an electrolyte additive, was added into electrolyte of dye-sensitized solar cell, and its effect on the performance of solar cells and mechanism were studied by electrochemical and spectral measurements. With increasing in EOP concentrations, the flatband potential of TiO2 electrode shifted negatively and the rate of interfacial recombination at the TiO2 electrode/dye/electrolyte interfaces was improved. The net effect of EOP was to improve the open-circuit photovoltage, indicating that the negative shift of conduction band of TiO2 was the predominated factor on determining the open-circuit photovoltage. The decline of short-circuit current of solar cell was ascribed to the slow dye regeneration and the low catalytic activity of counter electrode on triiodide reduction due to addition of EOP. [Copyright &y& Elsevier]