Iodine vapor doped polyaniline nanoparticles as a counter electrode for dye-sensitized solar cells

Abstract

In this study, we demonstrated the enhanced efficiency of dye-sensitized solar cells (DSSCs) using iodine vapor-doped nanostructured polyaniline (PANI)-based counter electrodes (CEs). Polyaniline nanoparticles were synthesized by chemical oxidative polymerization of aniline with oxidant ammonium persulfate (APS) using a surfactant, sodium dodecyl sulfate (SDS). The electrical conductivities of as-synthesized PANI emeraldine salt (PANI–ES) and dedoped emeraldine base (PANI–EB) increased from 3.1 S cm–1 to 9.3 S cm–1 and 2.0 × 10–5 S cm–1 to 0.5 S cm–1, and the doping levels increased from 38.2% to 41.8% and 3.2% to 33.3%, respectively, via iodine vapor doping. Compared with PANI–ES and PANI–EB CEs, iodine-doped PANI (PANI–ES–I2 and PANI–EB–I2) CEs with improved electrical properties demonstrated higher electro-catalytic activity toward I−/I3−redox couples, due to better charge carrier transport and reduced charge transfer resistance. The cells based on PANI–ES–I2 and PANI–EB–I2 CEs exhibited higher photovoltaic parameters and efficiency. Moreover, we successfully increased the cell efficiency of PANI–ES–I¬2 CE-based DSSCs to a maximum efficiency of ~7.86%.