Iodine vapor doped polyaniline nanoparticles counter electrodes for dye-sensitized solar cells

• PANI nanoparticles were developed as counter electrode materials for DSSCs.
• The conductivity of PANI layers was increased via I2 vapor-doping.
• Their structural analysis was characterized using XPS technique.
• I2 vapor-doped PANI electrodes showed higher catalytic activity than pristine ones.
• Photoelectrochemical properties of DSSCs were also investigated.

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). The electrical conductivities of chemically synthesized PANI emeraldine salt (PANI-ES) and dedoped emeraldine base (PANI-EB) were 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 of those were 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 PANIs (PANI-ES-I2 and PANI-EB-I2) CEs with improved electrical properties were 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 the PANI-ES-I2 and PANI-EB-I2 CE exhibited higher photovoltaic parameters and efficiency. Moreover, we successfully increased the cell efficiency of the PANI-ES-I2 CE-based DSSCs to a maximum efficiency of ~7.86%.