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Title: Active layer control for high efficiency perovskite solar cells
Author: Eperon, Giles E.
ISNI:       0000 0004 6061 9171
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2015
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The work documented in this thesis concerns the control and modification of semiconducting perovskite thin films for their use in perovksite solar cells (PSCs). PSCs are a promising new thin-film technology, offering both high solar to electricity conversion efficiencies and cheap fabrication costs. Herein, the boundaries of perovskite solar cell research are pushed further by tackling several challenges important to the field. Initially, this work focuses on understanding why the best PSCs made so far have been mesostructured devices, with the perovskite infiltrated into a scaffold. It is shown that this can be seen as simply a fabrication aid; without the scaffold, thin films easily dewet from the substrate. By understanding the crucial parameters important in carefully controlling this dewetting, it is minimised, and it is shown that scaffold-free planar heterojunction devices with high efficiencies can be fabricated. This work leads on to the next section; the development of semi-transparent perovskite solar cells. In their present state, PSCs cannot compete with silicon as stand-alone modules. Here, the morphological control has been leveraged to realise a different embodiment – semi-transparent perovskite devices for use in building-integrated photovoltaics. Competitive efficiency and transparency are demonstrated. Moreover, a hybrid self-tinting power-generating window concept is fabricated, by combining the photovoltaic and electrochromic technologies. In the third section of the thesis, the limitations of the most studied perovskite material, methylammonium lead halide, are addressed: its overly wide bandgap and thermal instability. To address these, the chemical constituents of the perovksite are altered, and the development of more efficient and more stable materials are reported. These are likely to be important for perovskite modules to pass international certification requirements for commercialisation. Finally, an in-depth study on the effect of ambient moisture, relevant for considering scale-up and the fabrication environment needed, is carried out. It is shown that the presence of some moisture during film fabrication allows a reduction of defect states in the perovskite material, enhancing device performance and film quality.
Supervisor: Snaith, Henry Sponsor: Oxford Photovoltaics Ltd
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Physics ; Perovskites