Flexible dye-sensitized solar cell combining light-cured polymer network, metallic grids and vertically aligned TiO2 nanotube array

Dye Sensitized Solar Cells gathered a widespread attention for the potential development of a very low cost photovoltaics, with versatile applications spamming from architectural integration to wearable photovoltaics and supply systems for low power electronics. However, some critical issues still have to be faced: the best performing DSCs are based on a rigid housing with glass/FTO electrodes, and steps towards the development of flexible devices have to be engaged. Moreover, the use of a liquid electrolyte is particularly critical, casting shadows on the possible durability of the device. During recent years we deepened a promising approach for the fabrication of quasi solid DSCs with excellent long-term durability. We thoroughly studied and characterized the integration of self standing polymeric membranes prepared by free radical photopolymerization, investigating different polymeric formulations. Very recently, this electrolytic system was integrated with an innovative design for DSC photoanode, based on the use of semitransparent metallic grids as a support for the sensitized nanostructured semiconductor. For photoanode fabrication, both the use of TiO2 nanotubes directly grown on bendable Ti mesh and the deposition of mesoporous layers of TiO2 nanoparticles were investigated with excellent results. The main advantage of this solution is the possibility to perform the high temperature sintering process (which is mandatory for a well performing semiconductor layer with good electron transport properties) before the integration on the final polymeric housing of the cell. We will illustrate our most recent results on the fabrication of fully flexible solar cells with metallic mesh-based anode and cathode, separated by a polymeric membrane charged with a I-based redox mediator. The electrochemical characterization of the transport properties of the device and a physicbased modeling of the system were developed. This kind of architecture satisfies the main requirements that a DSC has to fulfill: it is TCO-free, transparent, highly bendable and adaptable to complex shapes, and fabricated only with very low cost materials and with a simple and scalable technology.