Enhancing the Structural Stability of α-phase Hybrid Perovskite Films through Defect Engineering Approaches under Ambient Conditions

This thesis investigates methods whereby perovskite solar cell power conversion efficiency and material stability
may be improved. Hybrid perovskites have gained increased attention for optoelectronic applications due to
favourable properties such as strong absorption, facile processing, and changeable band-gap. Despite excellent
improvements in power conversion efficiency of devices, perovskite films are unstable, degrading with relative
ease in the presence of moisture, oxygen, light, heat, and electric fields. The focus of this thesis is on ambient
atmosphere stability, concerned with the influence of moisture in particular on perovskite film fabrication,
degradation, and device functionality. In order to shed light on the impact of ambient atmosphere on perovskite
films, experiments are designed to investigate films during fabrication and degradation. The influences firstly of
stoichiometry during ambient fabrication, and then ionic substitution (with caesium and formadinium) upon
moisture-induced degradation are investigated. Finally, films and devices with a novel composition
incorporating Zn are fabricated under ambient conditions to investigate the effect of Zn addition on perovskite
film stability.