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Title: Investigation of interface behaviour on perovskite solar cells
Author: Wang, Jacob Tse-Wei
ISNI:       0000 0004 6494 6874
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2016
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Historically, the interfaces and charge transportation layers dictate the performance in heterojunction solar cells. This thesis addresses the interface behaviours and the interfacial layers within perovskite solar cells (PSCs), and provides insights and practicable solutions to facilitate the realisation of efficient PSCs. To achieve efficient charge collection with interlayer fabricated with low-temperature processes, a graphene-TiO2 nanocomposite is demonstrated; By investigating the carrier transport, we found the insertion of graphene improved the electron collection efficiency with its high surface area and ballistic carrier conduction properties, and in conjunction with pre-synthesised TiO2, we have successfully circumvented the need for high-temperature annealing, enabling the whole device to be fabricated at under 150 °C. While the anomalous hysteresis behaviour which is widely observed in regular PSCs structure is a significant problem, the quest of stable PSCs seems to be answered by the use of inverted PSCs structures. We show a detailed development of inverted PSCs which are deconstructed layer by layer. Numerous approaches have been tailored to improve interfaces, and energy levels between layers, leading to an efficient and hysteresis-free perovskite solar cells. Lastly, an in-depth study of impurity doping is investigated using Al3+. The doping with small metal ions in the perovskite precursor has been found to influenced the crystallisation and optoelectronic properties of the perovskite crystals. Here, for the first time, the correlation between reduced structural crystal defects is clearly linked to enhanced photovoltaic properties, with the best performance for the lowest electronic disorder in the CH3NH3PbI3 crystal.
Supervisor: Nicholas, Robin ; Snaith, Henry Sponsor: Swire Education Trust
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: interface science ; perovskite solar cells ; condensed matter physcis