Exploring on Photovoltaic Performance of Dye-Sensitized Solar Cells Using Polyaniline as a Counter Electrode: Role of Aluminum-Solvent Interactions

In this work, we successfully synthesized aluminum-doped polyaniline in various solvent media using chemical oxidation polymerization, and for the first time, investigated their applications as counter electrode (CE) in dye-sensitized solar cells (DSSCs). The experimental results (field emission scanning electron microscopy/energy dispersive X-ray analysis, atomic absorption spectrometer, Fourier transform infrared spectroscopy, thermogravimetric/differential thermal analysis, etc.) showed that critical properties such as crystallinity, conductivity, and surface area of PAni polymers can be controlled through both Al ions and/or solvent media. The photovoltaic performance of DSSCs was evaluated by current density-voltage (J-V) and external quantum efficiency measurements. The differences in the conversion efficiencies (η) were explained based on the electrocatalytic abilities and electron transfer properties of CEs. Of the CEs in various solvents, the P@6 CE in acetone showed the best electrocatalytic ability and highest η of 5.97%. This is even higher than that of the cell with Pt CE (5.75%). Furthermore, its stability under a prolonged irradiation is somewhat lower or close to the Pt CE, P@6 CE based DSSC showed the characteristics of rapid activity onset, high multiple start/stop capability, and superior irradiation stability. This novel concept-along with promising electrocatalytic activity and facile electron transfer-provides a new approach to enhance the photovoltaic performances of Pt-free DSSCs.