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Nanostructured Photovoltaics Group

In the Nanostructured Photovoltaics group we aim developing solar cell device architectures that exploit the potential of nanotechnology. Our ambition is to unravel and tailor the optoelectronic properties of nanometer sized semiconductors for obtaining low cost-high efficiency solar cell and fuel devices. Our approach is multidisciplinary, combining fundamental research on sample's physico-chemistry with solar cell device engineering.

Fundamental understanding and eventual engineering of charge carrier transfer and transport at the nanoscale is one of our core competences and research interests. Our interest aligns with the fact that charge carrier dynamics determine the photoconversion efficiency of any solar converter. As nanoscale objects are defined by large area-to-volume ratios, surface chemistry play a pivotal role on object's functionality; furthermore, quantum confinement of charge carriers at the nanoscale make object's optoelectronic properties to be strongly tunable with structure. In this respect, establishing neat correlations between surface chemistry, structure and charge carrier dynamics taking place in nanostructured systems represent one of the most significant leading contemporary topics in material science.

Interfacial charge carrier dynamics in sensitized systems. The sensitization of mesostructured oxides by excitonic absorbers (e.g. quantun dots or molecular dyes) represent an appealing route for developing low cost photovoltaic and photocatalytic devices. We are interested on the analysis, modeling and ultimately fine-tuning of interfacial carrier dynamics in sensitized oxides with the aim of boosting photoconversion efficiency in solar energy conversion schemes (solar cells and fuels).

Charge transport in nano-structured systems. We are actively interrogating transport in nano-structured systems. THz spectroscopy is unique tool to characterize the nature of the photoconductivity with sub-ps resolution in a contactless fashion. This is due to the fact that, in contrast to other pump-probe techniques, apart from resolving carrier dynamics, THz spectroscopy allows for the identification and modeling of the photo-generated species (e.g. excitons vs free carriers) via the frequency resolved complex conductivity.

Third generation photovoltaics. A conventional solar absorber suffers from two intrinsic major energy loss channels: (1) its inability to absorb photons with energy less than the material absorption threshold and (2) the waste of photon energy when photons with energies above the absorption threshold are absorbed (cooling). These aspects set a 30% upper efficiency limit for single gap photoconverters (the Shockley-Queisser limit). Part of our research efforts are focused on identifying and engineering nanostructured systems for diminishing those energetic losses towards breaking the 30% photoconversion efficiency barrier.