Preparation of platinum-free tubular dye-sensitized solar cells by electrophoretic deposition

Abstract

Tubular dye-sensitized solar cells (DSSCs) were developed by replacing expensive materials with those of lower cost as follows: (1) substituting conductive glass electrodes for titanium (Ti) wires, and, (2) use of a mixture of multi-walled carbon nanotubes, MWCNTs and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), and PEDOT-PSS in place of a platinum (Pt) catalyst. Platinized counter electrodes were used as the standard counter electrodes for comparison. The effects of the chemical treatment of a titanium wire substrate and electrophoretic deposition conditions on the efficiency of the resulting DSSCs were also investigated. Chemical treatment of titanium wires was done by soaking the wires in HF-HNO3 solutions at three different concentrations, 0.8, 1.6 and 2.4 M, for three different soaking durations, 5, 10 and 15 min. The optimal condition was found to be a HF-HNO3 concentration of 0.8 M and a soaking duration of 10 min. Film coating on working electrodes was performed using an electrophoretic technique at three different voltages, 5, 8 and 10 V, and four different coating durations, 1, 3, 5 and 7 min. Then, the optimal voltage of 5 V and deposition duration of 5 min was applied for film deposition on counter electrodes. The efficiency of the resulting DSSC with a CNTs/TiO2 counter electrode was 0.03%. The addition of PEDOT-PSS improved the efficiency of this DSSC to 0.08%.