Plasticized I2-free polysiloxane ionic conductors as electrolytes for stable and flexible solid-state dye-sensitized solar cells

Abstract

For practical applications, flexible solid-state dye-sensitized solar cells (ss-DSSCs) with high photovoltaic performance and stability are paramount. A novel iodine (I2)-free polysiloxane based highly conductive poly(ionic liquid), which acts as the lone charge transfer intermediate, is used for the first time as an electrolyte in flexible 1D TiO2 nanotube photoanodes (TiO2 NT) based ss-DSSCs. The I2-free polymer electrolyte plasticized with ethylene carbonate (EC) leads to a higher power conversion efficiency in DSSCs involving TiO2 NTs than the I2-based polymer electrolyte, mainly due to improved Voc and Jsc. Apart from overcoming the visible light absorption loss, this I2-free polymer electrolyte also reduces the charge recombination and thus leads to higher electron lifetime in DSSCs. The I2-free DSSCs also displayed long-term stability measured under ambient and accelerated stability testing. The improvement is also due to the effective pore infiltration into the large pores of TiO2 NT structure in ss-DSSCs.