A Route to Fabricate Rapid and Efficient Dye-sensitized Solar Cells through Minimizing the Duration of TiO2 Film Disposition and Dye Sensitization

Abstract

Dye Sensitized Solar Cell (DSSC) technology is considered a promising substitute to the conventional silicon-based solar cells due to DSSC’s low material cost, ease of fabrication, low toxicity, and relatively high power conversion efficiencies. The two major steps of DSSC fabrication are: 1) formation of a mesoporous TiO2 layer on a transparent conductive oxide (TCO) coated glass substrate to make its photoanode, and 2) sensitization of the photo-anode with dye. Conventionally, photoanodes are prepared by depositing a mesoporous TiO2 layer on a TCO-coated glass substrate and sintering at a high temperature (~450 °C) for 30-60 minutes. The prepared TiO2 is then dip-coated in a dye solution for ~24 hrs. These processes have remained unchanged for almost 27 years and require more than 90% fabrication time of a typical DSSC. Thus, they limit the throughput and cost-effectiveness of this technology. This thesis introduces a novel technique to rapidly form mesoporous TiO2 films on FTO (fluorine doped tin oxide)- coated glass substrates using microwave irradiation with essentially identical performance as conventional heating. Microwave (MW) assisted films were prepared at low temperatures (\u3c 260 °C) within less than 10 minutes. DSSCs fabricated with 8 minutes of MW irradiated films show similar efficiencies with that of conventionally fabricated DSSCs. Besides saving time, and energy compared to its counterpart, this approach may pave the way of plastic-based electronics. This thesis also demonstrates the rapid (\u3c 30 minutes) loading of two Functionalized Carboxylate Deposition (FCD) dyes through high vacuum (0.1 mTorr) FCD. The power conversion efficiency (PCE) achieved with the FCD DSSCs were higher than dip-coated DSSCs. Combinedly, microwaveassisted photoanode preparation, and FCD dye-sensitization can save more than 90% fabrication time for future ultra-low cost DSSCs