Fabrication and Application of a Carbon Counter Electrode with Excellent Adhesion Properties for Dye-Sensitized Solar Cells

Abstract

The aim of this study was to resolve the poor bonding strength between carbon film and the conductive substrate in a carbon counter electrode. A carbon black-conductive carbon (Cb-CC) counter electrode was fabricated using a low-cost commercial conductive carbon paste (CC) as a binder and carbon black (Cb) as a catalyst. Film adhesion test results indicated that the introduction of the CC significantly improved the adhesion between Cb and the conductive substrate, as well as the conductivity and stability of the carbon counter electrode. The porous structure of the mixed CC and Cb carbon films was maintained as illustrated by scanning electron microscopy (SEM). Cyclic-voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements showed that the catalytic activity of CC-Cb was superior to that of CC. A dye-sensitized solar cell (DSSC) based on the CC-Cb counter electrode exhibited an excellent photoelectrical performance, reaching an energy conversion efficiency of 6.54%. The amount of CC in the carbon counter electrode was further optimized. Consequently, when the mass ratio of Cb:CC reached 23:77, the corresponding DSSC yielded the highest energy conversion efficiency recorded in this study at 6.81% . In addition, long term stability testing showed that the photovoltaic parameters of the DSSC based on the CC-Cb counter electrode remained similar to the initial values following more than 700 h of light soaking. This work has laid the foundation for improving the stability and the industrialization of low-cost DSSCs.