Novel ITO/arc-TiO2 antireflective conductive substrate for transmittance enhanced properties in dye-sensitized solar cells

A novel antireflective TiO2 compact layer (arc-TiO2) that can improve transmittance is employed by radio frequency sputtering at the interface between ITO and porous-TiO2. Effects of the absence and presence of the TiO2 layer were mainly investigated by means of incident photon-to-current efficiency (IPCE), open-circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). The sensitization effect of N719 dye has been improved due to the right-shifted transmittance spectra as shown by IPCE measurement. The slow decay behaviour of the photo-voltage attributed to the merits brought by the compact layer has been evidenced by the OCVD measurement. The improvement of adhesion between the arc-TiO2 film and porous-TiO2 has decreased the interfacial resistance R1 in the EIS measurement, and this facilitated the charge transfer process of the electron in the dye-sensitized solar cells (DSSC) later on. A remarkable improvement in the overall conversion efficiency of 3.444%, representing almost 50% increment compared to the cell without the compact layer, is mainly responsible for the higher transmittance and fewer recombination effects of the arc-TiO2 compact layer employed in the DSSC.