The Stability and Manufacturability of Emerging Thin Film Photovoltaic Technologies

In order for a photovoltaic device to be commercially viable it must have a production cost and operational stability commensurate with its final application. Both of these properties are influenced by many factors, including the production of the active materials and the deposition techniques used to fabricate it. In this thesis, the stability and manufacturability of two emerging photovoltaic materials are examined: organic semiconducting polymers and organic-inorganic perovskites. Organic semiconducting polymers are commonly synthesised through reactions utilising metal catalysts, which can remain with the polymer after synthesis, necessitating the investigation of their influence on photovoltaic devices. This work shows that the presence of the residual catalyst palladium in PCDTBT organic photovoltaic (OPV) devices caused significant reductions in power conversion efficiency and an additional increase in efficiency loss during the first 60 hours of operation. It is also shown, however, that only minor losses occurred in PFD2TBT-8 OPV devices at high Pd concentrations, highlighting the need to examine individual material systems. Despite being a very new technology, perovskite solar cells (PSCs) have already achieved comparable performance to silicon solar cells, making it important to investigate the stability of such devices. The operational stability of PSCs in the inverted architecture was characterised, showing lifetimes of <300 hours. Using spectroscopic and device characterisation techniques, the major loss mechanisms were revealed to be reactions with water and oxygen, resulting the in the decomposition of the perovskite. It is also examined how the addition of hydroiodic acid to the perovskite precursor solution affects the performance and stability of spin and spray coated PSCs. Finally, the effects of deposition temperature and additional annealing on the operational stability of PSCs was investigated.