Dye-sensitized solar-cells performance of 4,5-diazafluoren-9-one based cobalt (II/III) redox mediator

Solar energy systems, including photovoltaics, show a rapid increase in development and industrialization and constitute to a very significant part in the field of renewable energy researches. Dye-sensitized solar cells (DSSC) achieve direct sunlight-to-electricity conversion by partially mimicking photosynthesis, rendering it a unique photovoltaic technology. Redox mediators play a major role determining the photocurrent and the photovoltage in DSSCs. To maintain the photocurrent, the reduction of oxidized dye by the redox mediator should be significantly faster than the electron back transfer between TiO2 and the oxidized dye. Since the discovery of DSSCs, the iodide/tri-iodide redox couple has been conventionally used as the redox mediator. However, I-/ I3- redox system has a mismatch between its redox potential and dye redox potential. In addition, it has been observed that there may be problems of corrosiveness and visible light absorption. These disadvantages were overcome with one-electron-transfer cobalt complexes with more positive redox potentials, which resulted in an improved photovoltage. In this work, synthesis and photovoltaic measurements of novel [Co(DAFO)3]2 +/3+ complexes containing 4,5-Diazafluorene-9-one (DAFO) were analyzed. The effect of photovoltaic measurements on different solvents, semiconductors and counter electrodes was investigated. The structures of Co+2/Co+3 complexes were examined by FTIR, UV-Vis, H-NMR and MS. Co+2/Co+3 complexes photovoltaic measurements were performed under 1-sun intensity (100 mW/cm2) which genereted by calibrated silicon photodiode. As a results, the solar energy conversion efficiency of C4 and C7 electrolytes were 0.3% and 0.11% are the best efficiency of this study.