Studies On Highly Efficient Large-scale Dye-Sensitized Solar Cells

Since serious energy crisis and environmental concern, solar energy has attracted significant attention as a kind of clean and renewable energy. In relative terms of human society, solar energy is an renewable source. In respect that there is no environmental pollution caused by the fabrication and utilization of solar energy, solar energy is a real green energy. It is well known that the conventional silicon cells suffer from high cost, shortage of materials, and environmental pollutions. However, dye-sensitized solar cell (DSC) is a new type of photovoltaic cell with the advantages of simple manufacture, wide application, and high theoretical photoelectric conversion efficiency. In this paper, in order to prepare high efficiency and low-cost large-scale DSCs, we investigated the components, the internal configuration, the model of efficiency, and the practicability of large-scale DSCs.First, the components of large-scale DSCs were prepared and optimized. The high-efficiency, stable, and uniform TiO2 films were obtained by adjusting TiO2 pastes and the method of film fabrication. The platinum electrodes with high light transmittance were prepared by spray pyrolysis. The catalytic performance of these platinum electrodes was comparable with the ones prepared by sputter deposition. Moreover, we optimized the silver conductive pastes and the preparation parameters for silver gate electrodes. In order to obtain the large-scale DSCs with high photovoltaic performance and stability, we also studied the electrolytes with different solvents, which were acetonitrile,3-methoxypropionitrile, and 1-ethyl-3-methylimidazolium tetrafluoroborate. Furthermore, the purification of N719 acted as photo sensitizer was helpful to further improve the efficiency of large-scale DSCs.Second, we prepared sandwich W-interconnected large-scale DSCs, sandwich current-collecting large-scale DSCs, and series-parallel hybrid-connection large-scale DSCs with independent units. The W-interconnected large cells and current-collecting large cells showed a good superposition of voltage and current, respectively. In the series-parallel hybrid-connection large cells, the high voltage and current could be outputted by different connections. The flexibility of output in the series-parallel hybrid-connection cell made it suitable for the various requirements. An above 5% of the photoelectric conversion efficiency was obtained by 5X7 cm2 current-collecting large cells under one sun conditions.For series-parallel hybrid-connection large cells in the size of 10×10 cm2, the photoelectric conversion efficiency was nearly 4% under one sun conditions, in which series voltage and parallel current could be 4.68 V and 594.94 mA, respectively. Moreover, after two months of the stability test under the indoor working condition, the efficiencies of the cells were maintained above 90% compared with the initial values.Third, on the basis of physical and geometric parameters, a semi-empirical mathematical model of the efficiency was built for different configurations of large-scale DSCs. We investigated three configurations of large-scale cells, which were the series, the parallel, and the series-parallel hybrid connections of independent units. The applicability of the model was analyzed by contrasting the calculated efficiencies with the measured ones. The influences of the physical and geometric parameters on the cell performance were analyzed based on the semi-empirical mathematical model. It was found that the optimization of the performance of large-scale cells could be performed by the semi-empirical mathematical model in theory.At last, we prepared the colorful and the artistic large-scale DSCs, as well as large-scale DSCs with rigid and flexible substrates. These cells acted as both the power generation and environmental decoration. This research could promote the application of large-scale DSCs in practicability.