Effect of molecular-level insulation on the performance of a dye-sensitized solar cell: Fluorescence studies in solid state

The performance of a dye-sensitized solar cell (DSSC) that is based on the host-guest encapsulation of 5-[4-diphenylamino)phenyl]thiophene-2-cyanoacrylic acid (L1) inside β-cyclodextrin hosts has been tested. The formation of the complex in the solid state and when adsorbed on TiO₂ was characterized using steady and picosecond time-resolved emission techniques, as well as time dependent DFT calculations. The molecular-level insulation has led to a small enhancement in the energy-conversion performance of the fabricated DSSC with the best results being an increase in the open circuit voltage (Voc) from 0.7 to 0.8 V. The importance of the present investigation lies in the unique spectroscopic characterizations of the examined materials in the solid state.