Low-cost Counter Electrodes For Dye-sensitized Solar Cells

Dye-sensitized solar cells (DSCs) have attracted much attention due to its low cost, environmental friendliness, simple fabrication and high power conversion efficiency. Counter electrode (CE), as an important part of DSC, generally applies an F-doped tin oxide (FTO) glass coated with a Pt film. However, not only Pt is scarce and noble metal, but also FTO is very expensive, and the fabrication procedure of Pt CE commonly used is complex, which account for the persistently high cost of CEs for DSC. Preparation of highly efficient and low-cost CE will be in favor of reducing cost of DSC fabrication, promoting the process of industrialization, and enhancing the competitiveness and application area for DSCs among various photovoltaic devices. Therefore, this paper mainly focuses on preparing highly efficient and low cost CE, aiming at developing simple manufacture procedure for Pt CE as well as novel low-cost CE catalysts and substrates.Firstly, in order to decrease the dosage of Pt, a simple dip-coating method is developed to prepare rigid Pt/FTO and flexible Pt/ITO-PEN CEs, which is hypothermal and simple in operation fitting for large-area manufacturing. Results of J-V, CV, SEM, and UV-Vis absorption measurements show that the prepared Pt CEs can display excellent efficiency and high transparency with low Pt loading amount.Next, three Pt-free catalysts, including titanium carbide (TiC), tungsten oxide (WO2), and vanadium nitride (VN) are introduced into DSC as CE catalysts, and Pt-like catalytic activities are obtained. Moreover, three kinds of FTO-free substrates, involving rigid bare glass (BG). and flexible Ti foil and polyimide film are applied to prepare Pt-free and FTO-free CEs. receiving excellent performance. The performances of DSCs using Ti foil as substrates are superior to those using FTO glasses as substrates. To further improve the catalytic activities of the Pt-free catalysts mentioned above, Pt and TiO2nanoparticles are added to form binary or ternary composites, gaining a substantially enhancement of their performances.Last but not least, taking practical use of DSCs into consideration, the Pt CE prepared using dip-coating method and the Pt-free catalysts are drawn into large-scaled DSC modules. DSC modules in serial connection with the area of5×5crrT are designed and prepared, achieving high power conversion efficiency of6.84%with high open-circuit voltage of over2.7V. Furthermore, long-term stability tests are carried out under outdoor or light-soaking conditions. The as-prepared DSC modules can retain splendid photovoltaic properties suffered from1000h aging tests, indicating superb stability they possessed.