| It’s pressing need to develop the novel solar cell, because the expense of conventional solar cells is high but the energy crisis is becoming more and more rigorous. Dye-sensitized Solar Cells (DSSCs), as a prospecting candidate for new generation solar cells, have attracted widespread attention since DSSCs was put forward in 1991 and now the efficiency has achieved 12.3%. However, the system of DSSCs is complex as a result of the interfaces, which restricts the capability of DSSCs to improve further. TiO2 nanoporous films, as a conventional material, play an significant role on the electron transmission and the adsorption of dyes. So trap states of TiO2 nanoporous films have influence on the property of DSSCs. Generally, trap states mainly result from impurities, interface adsorption of ions, and the breakdown of the lattice periodicity in the semiconductor, dangling bonds and/or the rearrangement of the surface atoms. Trap states have significant impacts on the charge transport and recombination in DSSCs and further influence on the efficiency of DSSCs. But to the best our knowledge, the test means of trap states have not been discussed systematically and the influence of experimental conditions on trap states has not been studied and reported in detail.In this paper, measurements of trap states are introduced and analyzed comprehensively at the first, which could provide some reference for the analysis of trap states. Secondly, this paper research the influence of different experiment conditions on trap states (the different time, temperature, pH of hydrothermal reaction), which could provide support in theory for ideal conditions of TiO2 synthesis. And we employed the cyclic voltammetry (C-V) measurement conjugating with the electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) to investigate the differences of trap states among different samples. This work will be conducive to prepare the preeminent TiO2 photoanode for a high-efficiency DSSCs. |
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