RF sputtered tri-functional antireflective TiO2 (arc-TiO2) compact layer for performance enhancement in dye-sensitised solar cell

Abstract

A novel antireflective TiO2 compact layer (arc-TiO2) that can reduce electron recombination and improve transmittance was deposited by RF magnetron sputtering at the interface between indium tin oxide and porous-TiO2layer of a dye-sensitised solar cell (DSSC). Effects of the arc-TiO2 thicknesses on the performance of the arc-TiO2-based DSSC were investigated by means of incident photon-to-current efficiency (IPCE), open-circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). The sensitisation effect of N719 dye was remarkably improved due to relatively higher and red-shifted transmittance spectra of the ITO/arc-TiO2 electrode in a specific region, and evidenced by the IPCE measurement. Meanwhile, the slow decay behaviours of the photo-voltage owed to the compact layer were verified by the OCVD measurement. The adhesion enhancement between the arc-TiO2 film and porous-TiO2 layer decreases the interfacial resistance R1 in the EIS measurement, hence facilitating the charge transfer process of the electrons in the DSSC. A significant improvement in the overall solar energy-to-electrical conversion efficiency, which constituted almost 50% higher compared with the uncoated ITO cell, is mainly attributed to the higher transmittance and reduced recombination of the arc-TiO2 film employed as the tri-functional compact layer in the DSSC.