Excitonic solar cells represent an appealing class of the third-generation photovoltaics, aiming at increasing the photoconversion efficiency, while applying inexpensive, simple and scalable processes for cell fabrication. Critical to the success of excitonic solar cells is the process of exciton generation, charge separation at the hetero-interfaces inside the cell, and charge transport. Suitable modulation of the interface of nanomaterials can guarantee fast charge collection and reduced charge recombination, which typically affect photoconversion efficiency in end-user devices.
We are developing a research line on preparation and characterization of engineered nanomaterials for application in excitonic solar cells. These materials include: wide-bandgap semiconductors as photoanodes in dye sensitized and quantum dot sensitized solar cells (DSSCs and QDSCs, respectively); semiconducting quantum dots either colloidal or directly grown on the oxide surface, and counterelectrodes catalyzing the charge exchange at the cathode of DSSCs and QDSCs.
Nanostructured hierarchically self-assembled oxides (TiO2, ZnO, SnO2) are produced with physical and chemical routes. Increased specific surface, high light scattering and enhanced electron transport are required to guarantee high optical density of the active layer, high transport of the photogenerated charge and reduced recombination during charge collection. The characterization of the physical and chemical processes related to charge photogeneration, transport and collection are investigated through state-of-the-art experimental techniques, correlating the interfacial properties of the composite materials and the prototype devices.