Platinum nanoparticle/ self-doping polyaniline composite-based counter electrodes for dye-sensitized solar cells

In this study, we developed a series of platinum nanoparticle (PtNP)/self-doping polyaniline (SPANI) composite-based counter electrodes for dye-sensitized solar cells (DSSCs). The SPANIs with nanospherical (S-SPANI) and nanotube (T-SPANI) structures were respectively self-assembled on the indium-tin oxide glass substrate via the in situ oxidation polymerization. The S-SPANI and T-SPANI were prepared by the copolymerization of self-doping monomer o-aminobenzenesulfonic acid and aniline in different molar ratios. The PtNP/SPANI composite-based counter electrodes were further prepared through the reduction of Pt ions on the SPANI layer using reduction agents of formic acid and sodium borohydride (NaBH4). The SPANI can serve as the proposed supports to disperse PtNPs. The particles sizes of formic acid-reduced nano-platinum (F-PtNPs; 5-15 nm) were smaller than those of the NaBH4-reduced nano-platinum (S-PtNPs; 15-25 nm). Moreover, the distribution of F-PtNPs on the surface of SPANIs was more uniform than that of the S-PtNPs on the surface of SPANIs. The effects of SPANI morphology and PtNP size/distribution on the electrochemical behavior and photovoltaic performance of these PtNPs/SPANI counter electrodes-based DSSCs were studied. The highest short-circuit current density (14.87 mA cm(-2)), fill factor (64.2 %), and photoenergy conversion efficiency (4.77 %) were obtained for the DSSC based on the F-PtNP/S-SPANI counter electrode.