Charge recombination reduction in dye-sensitized solar cells by depositing ultrapure TiO2 nanoparticles on “inert” BaTiO3 films

Ultrapure TiO2 nanoparticles (∼5 nm in size) were supported on “inert” BaTiO3 films by TiCl4 treatment, which was used to fabricate dye-sensitized solar cells (DSSCs). The optimized electrode, designated as BaTiO3/TiO2(4), was obtained upon four cycles of TiCl4 treatment. DSSC with BaTiO3/TiO2(4) electrode exhibits superior power conversion efficiency (PCE) compared to that with conventional anatase TiO2 (∼25 nm in size) electrode. The interfacial charge recombination kinetics was investigated by electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS). In contrast to DSSC with anatase TiO2 electrode, the dramatically enhanced electron lifetime for DSSC with BaTiO3/TiO2(4) electrode could be attributed to the decrease of recombination reaction at the TiO2 photoelectrode/electrolyte interface. It is proposed that the lower interfacial charge recombination can be related to the relatively shallower trap distributions in DSSC with BaTiO3/TiO2(4) electrode.