Efficiency enhancement of dye-sensitized solar cells by interface modification between photoanode and electrolyte

A nanoporous TiO2 layer on a transparent electrode was modified with an aqueous lithium hydroxide solution by a simple dipping process, and effects of the modified electrode on the photovoltaic properties of dye-sensitized solar cells were investigated. The modification led to a considerable improvement of 23.6% in power conversion efficiency due to an increase in both open circuit voltage and fill factor. From the measurements of the electronic band structure, electrochemical impedance spectra and incident photon-to-current conversion efficiency, it was revealed that the modification by LiOH formed a surface dipole on the TiO2 electrode, leading to a negative shift of conduction band edge of TiO2.