Novel paradigms for resonance energy transfer mediated hybrid photovoltaic devices

Abstract

This work focuses on the utilisation of quantum dots (QDs) and resonance energy transfer to enhance the properties of existing photovoltaic technologies. Time-resolved spectroscopy is used to demonstrate that lead sulphide (PbS) QDs could be used to enhance the absorptivity of silicon solar cells. In this scheme, QDs deposited on the solar cell act as absorber, while the photogenerated excitons are transferred to the underlying silicon to contribute to the photocurrent. QD hybridization is also demonstrated in InGaP solar cells. In this case, the QDs are used to mitigate the poor utilisation of the energy absorbed in the AlInP window layer. Excitons generated in this layer are non-radiatively transferred to the QDs, which emit photons below the AlInP band-gap to generate carriers close to the depletion region of the p-n junction. The overall performance of the solar cell is found to be significantly improved after hybridization, with a large 14.6% relative and 2% absolute enhancement of the photon conversion efficiency. Finally, the integration of QDs into thin film Cu(In,Ga)Se2 (CIGS) solar cells is investigated. The deposition of a non-uniform layer of QD aggregates in close proximity to the heterojunction is found to provide a 10.9% relative enhancement of the photon conversion efficiency. Enhancements of the external quantum efficiency in both the blue and near-IR ranges are attributed respectively to radiative luminescent down-shifting from the QDs and to scattering on QD aggregates. Throughout this thesis, evidence is provided that placing efficient nanocrystaline emitters near (<

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Identifiers

ORCID for Pavlos Lagoudakis: orcid.org/0000-0002-3557-5299

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