Optimization of TiO2 nanoparticle mixed PEDOT–PSS counter electrodes for high efficiency dye sensitized solar cell

Abstract

Poly(3,4-Ethylendioxythiophene)–Poly(Styrene Sulfonate) (PEDOT–PSS) mixed with titanium dioxide (TiO2) nanoparticles was coated on conductive glass substrate by a doctor blading method and used as dye-sensitized solar cell (DSSC) counter electrodes. The energy conversion efficiency is significantly improved after TiO2 nanoparticle incorporation. This improvement is attributed to an increase in counter electrode catalytic activity and a decrease in counter electrode charge transfer resistance. These phenomena were observed using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS), respectively. The efficiency of polymer-TiO2 based DSSCs varied with the ratio of small (~25nm) to large (~100nm) TiO2 nanoparticles. The highest efficiency (~8.49%) was obtained with a ratio of 30% large to 70% small (wt/wt) nanoparticles inTiO2 electrodes. This efficiency is superior to that of Pt DSSC (~7.50%).