High-performance/low-temperature-processed dye solar cell counter electrodes based on chromium substrates with cube-like morphology

• Cyclic electrodeposition of Pt on cube-like Cr films provides efficient counter electrodes.
• The rough Cr coating can be electrodeposited on large area with low cost.
• Highly dispersed Pt nanoparticle layer on defect sites and edges of Cr cubes is formed.
• Rct as low as 0.27 Ω cm2 and solar cell efficiency more than 9% is obtained.
• Cr and Pt depositions are made at low temperature, hence are suitable for flexible DSCs.

There is still an open question of how to prepare high-performance counter electrodes for dye solar cells (DSCs) at room temperature; a requirement for flexible DSCs. Here, we introduce Pt deposited cube-like chromium coating as a low-temperature highly-efficient counter electrode for DSCs. Cr is a chemically stable metal and can be easily electroplated on conductive substrates with high roughness (here ∼160 nm) and cube-like appearance. A cyclic electrochemical deposition method with optimized temperature and number of cycles is used to grow Pt nanoparticles on this surface and charge transfer resistance as low as 0.54 Ω cm2 and 0.27 Ω cm2 were obtained at 40 °C and 55 °C solution temperatures, respectively. More surface defects (kinks, terraces and ledges) on the cube-like chromium film, as well as the electric field enhancement near the cube edges produces more dispersed Pt nanoparticles on this substrate compared to FTO (fluorine doped tin oxide) substrate. By replacing the conventional DSC counter electrode (thermal Pt on FTO) with this new electrode, filling factor and efficiency increase from 0.63–6.6% to 0.68–8.77%, without a scattering film. The efficiency can be as high as 9.52% by using a scattering film.

Figure optionsDownload as PowerPoint slide