Effects of different solvent baths on the performances of dye-sensitized solar cells: Experimental and theoretical investigation

• CD-7-sensitized photoanodes by THF or DMF bath have been prepared.
• The results are studied by experimental analyses and computational modeling.
• Different solvent baths have different effects on dye aggregation and adsorption.
• Different solvent baths have significant influences on IPCE and electron lifetime.
• The different photovoltaic properties of the DSSCs have been investigated.

Combining experimental analyses and computational modeling, we investigated CD-7-sensitized solar cells (DSSCs) by THF or DMF bath with aim to understand the effects of different solvent baths on the performances of the corresponding DSSCs. In experiment, the photophysical, photovoltaic and electrochemical impedance properties of the DSSCs based on THF or DMF bath were investigated. The UV–vis spectrum of CD-7 in THF is red-shifted in comparison with it in DMF, indicating that there are different interactions between CD-7 and the solvent molecules. The UV–vis spectrum of CD-7 adsorbed on TiO2 film suggested that different solvent baths have different effects on the J-aggregation and absorption strength. Monochromatic incident photon-to-electron conversion efficiency (IPCE) and electrochemical impedance analyses showed that different solvent baths have significant influences on the IPCE values and electron lifetimes of the corresponding DSSCs. The analysis results of computational modeling showed that the solvent molecules would affect the energy level of TiO2, adsorption structure and adsorbed amount of CD-7 on the TiO2 film. The above analysis results illuminate a big difference in the performances of DSSCs by THF or DMF bath. The DSSCs based on THF bath obtained the η value 1.53%, which is about twice as much as that of DMF bath.

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