Phycobilisomes Coupling With Chlorin E₆ Sensitized Solar Cells

Solar energy is known as an ideal energy fundamentally solving the energy crisis and environmental problems. Dye-sensitized solar cells (DSSC) attract scientists'attention for their low-cost and high efficiency, and the using of natural dyes has become a trend in DSSC research. Phycobilisomes are used as photosynthetic light-harvesting antenna of red algae and cyanobacteria, which have the same function as the sensitizer for DSSC, and it is crucial to maintain the long-term stability of phycobilisomes as DSSC sensitizer. In this thesis, the factors affecting phycobilisomes stability, peptide surfactants stabilizing phycobilisomes, and phycobilisomes coupling with Chlorin e6 used as DSSC sensitizer were studied.Intact phycobilisomes were successfully isolated from Spirulina platensis using sucrose density gradient ultracentrifugation method, and it was investigated the effect of solution pH, phosphate buffer concentration, and phycobiliprotein content etc on the stability of phycobilisomes. The results showed that the optimal conditions for phycobilisomes stabilization were pH7.0, 1.0mol/L phosphate buffer, and as high as phycobiliprotein content.Zwitterionic surfactant A6K-COOH, cationic surfactant A6K-CONH2 and anionic surfactant A6D-COOH were selected to stabilize phycobilisomes. The results showed that low-concentration peptide surfactants could maintain the intact phycobilisomes structure, the peptides could prevent the decrease of energy transfer efficiency at concentrations above the critical micelle concentrations (CMC), and the thermal stability of phycobilisomes was improved by peptide surfactants at 5×CMC, with A6K-CONH2 being the best.The conditions for the formation of ZnO seeds were optimized, and ZnO nanowires (zincite, syn) were synthesized on the FTO glass by hydrothermal method. It was found that good distribution of ZnO seeds with particle size of 30~40nm on the FTO glass surface could be obtained with 1mmol/L zinc acetate in ethanol as precursor, seeding five times, and annealing 3 times at 350°C. The diameter of ZnO nanowires was 100~150nm, length was 3~4μm, and with good light permeability.Dye-sensitized solar cells were assembled using phycobilisomes coupling with Chlorin e6 as sensitizer, TiO2 thin films and ZnO nanowires as photoelectrodes, and their photoelectrical properties were studied. The result showed that the sensitization of Chlorin e6 was superior to phycobilisomes. Phycobilisomes coupling with Chlorin e6 could significantly improve the photoelectrical properties of DSSC. The short-circuit current, open circuit voltage,fill factor and photoelectric conversion efficiency of DSSC assembled with TiO2 thin films as photoelectrode were 0.33mA/cm2, 0.71V, 0.16 and 0.037% respectively, with enhancement of 44%, 0.04V, 88% and 1.6 times compared with Chlorin e6 respectively. Coupling extended spectral response range and increased the photoelectric conversion efficiency of DSSC.