Highly Transparent and Efficient Counter Electrode Using SiO₂/PEDOT–PSS Composite for Bifacial Dye-Sensitized Solar Cells

A highly transparent and efficient counter electrode was facilely fabricated using SiO2/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) inorganic/organic composite and used in bifacial dye-sensitized solar cells (DSCs). The optical properties of SiO2/PEDOT-PSS electrode can be tailored by the blending amount of SiO2 and film thickness, and the incorporation of SiO2 in PEDOT-PSS provides better transmission in the long wavelength range. Meanwhile, the SiO2/PEDOT-PSS counter electrode shows a better electrochemical catalytic activity than PEDOT-PSS electrode for triiodide reduction, and the role of SiO2 in the catalytic process is investigated. The bifacial DSC with SiO2/PEDOT-PSS counter electrode achieves a high power conversion efficiency (PCE) of 4.61% under rear-side irradiation, which is about 83% of that obtained under front-side irradiation. Furthermore, the PCE of bifacial DSC can be significantly increased by adding a reflector to achieve bifacial irradiation, which is 39% higher than that under conventional front-side irradiation.