Manufacturability aspects of printable electronics and halide perovskite photovoltaics

• Main Author: Cronin, Harry M.
• Other Authors: Silva, S. R. P. ; Shkunov, Maxim
• Published: University of Surrey 2018
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.736910

Manufacturing electronic devices by printing or coating is a key emerging technology, promising low cost and high throughput. Halide perovskites have emerged as high efficiency, solution processable photovoltaic materials, and within this thesis some of the issues relevant to their up-scaling are explored. Additionally, photo-curing – a post-processing technique with a wide range of applications in printed electronics – is investigated. Aqueous silver flake inks are a promising material for printed conductive applications, combining low cost and high conductivity. Within this thesis, photo-curing of these inks to further improve their conductivity is investigated. Photo-cured samples showed an 11x conductivity improvement compared with thermally cured samples. Furthermore, the manufacturing yield was doubled following photo-curing. These novel observations are explained, by recourse to percolation theory, by an increase in mean particle size. These results enable lower cost and increased yield in future manufacturing. Halide perovskite materials show great promise for solution processable photovoltaics. Within this thesis, the effects of ambient conditions during device processing are measured, in order to inform future up-scaled manufacturing. The chemical and morphological effects of ambient humidity in perovskite films are correlated with the annealing time used and final device performance. This work led to new insights into the combined effects of these two parameters, and a suggestion is made for reducing the annealing time. Finally, a barrier to commercialisation of perovskite solar cells is the use of toxic solvents in their fabrication. Within this thesis, a novel deposition technique is proposed, based on the synthesis of perovskite material in particulate form followed by re-dispersal in non-toxic solvents. This mitigates solvent toxicity, reduces sensitivity to ambient conditions, and in some cases enhances stability. Devices are fabricated based on this technique, and though performance remains low, a marked improvement is observed by the addition of conductive graphene flakes to the inks.