Examination of the sintering process dependent micro- and nanostructure of TiO2on textile substrates

Eco-friendly and sustainable power generation is one of the important aims of our time. Harvesting renewable energy can, e.g., be done by solar cells. For the integration in textiles, developing solar cells with typical textile haptics and pliability would be ideal. Additionally, textile solar cells should be created from low-purity materials in low-cost processes to be compatible with the textile industry. Thus, dye sensitized solar cells are ideal candidates for the integration of solar cell technology into textiles. In a recent project, we systematically test different material systems applied on textiles in which all functional layers are varied. One of the most crucial points is the sintering process of TiO2 which is only possible on a few textile materials. Additionally, the TiO2 coating itself contains the risk of being not completely isolating, allowing for dye and electrolyte or textile fibers penetrating through this layer and reaching the front electrode. This can result in short circuits or undesired counteracting voltages and currents. The article shows how different coating and sintering technologies of TiO2 on glass and textile fabrics influence the structures of the respective layers on different scales. It illustrates the differences between glass and textile fabrics in terms of the coating process and the resulting layer properties. Time-dependent measurements of open-circuit voltages and efficiencies show the physical implications of variations of the TiO2 layer structure and the resulting inner surfaces. In this way, we depict the different effects arising from undesired modifications of the TiO2 layer structure.