Platinum/polyaniline transparent counter electrodes for quasi-solid dye-sensitized solar cells with electrospun PVDF-HFP/TiO2 membrane electrolyte

Composite films of platinum and polyaniline (Pt/PANI) with different Pt loadings are prepared by chemical reduction and then a spin-coating process on fluorine-doped tin oxide (FTO) substrates. The obtained Pt/PANI transparent counter electrodes are applied in quasi-solid dye-sensitized solar cells (QDSCs) from front and rear light illuminations, using electrospun poly(vinylidenefluoride-co-hexafluoropropylene)/TiO2 (PVDF-HFP/TiO2) as the electrolyte. The analytical results show that the 1.8-nm sized Pt nanoparticles are distributed uniformly in the Pt/PANI film when the Pt loading is 1.5 μg cm−2. Electrocatalytic activity of the Pt/PANI electrode with 1.5 μg cm−2 Pt loading for the I3−/I− redox reaction is higher than the conventional sputtered Pt electrode. Furthermore, the mean optical transmittance of the Pt/PANI electrodes is above 60% in the wavelength of 400-800 nm. The optimal QDSC composed of Pt/PANI with 1.5 μg cm−2 Pt loading exhibits power conversion efficiencies of 6.34% and 3.85%, when measured using an AM1.5G solar simulator at 100 mW cm−2 under front and rear light illuminations. The efficiencies are both higher than those of the QDSCs employing the conventional sputtered Pt counter electrode with 8.3 μg cm−2 Pt loading. Moreover, the QDSC exhibits superior long-term stability. These promising results make the potential application of Pt/PANI films as cost-effective, transparent counter electrodes.