Platinum/carbon black composites as counter electrodes for high-performance dye-sensitized solar cells

Low-cost counter electrodes for dye-sensitized solar cells (DSSCs) are prepared using platinum/carbon black (Pt/CB) composites via a spin-coating process. Ethyl cellulose (EC) is used as a binder to regulate the viscosity of the Pt/CB composites to facilitate the spin-coating process. The ratio of Pt to CB is ca. 1:3. The effects of film composition (Pt/CB:EC = 30:15, 30:4) and number of coating layers on the electrochemical properties of the Pt/CB electrodes and the performance of the corresponding DSSCs are studied. The results show that Pt/CB films with the lower concentration of EC (Pt/CB:EC = 30:4) exhibit high electrochemical activity, low charge transfer resistance, and good DSSC performance. These results are attributed to the lower loading of EC, which facilitates the charge transfer of the electrodes. DSSCs using these Pt/CB composite counter electrodes with lower loading of EC achieve a high conversion efficiency (8.06%) comparable to that of cells using Pt.