Heterojunction Interface Control in Perovskite Solar cells

Perovskite solar cells have emerged as a likely contender for main stream photovoltaic solar energy conversion to electricity. They are currently at over 20% power conversion efficiency, however, the maximum efficiency which could be achieved is over 30% for single junction cells, and over 40% for multi-junction cells. In order to achieve this, major losses in the solar cell operation require identifying and mitigating. It is most likely that most losses in perovskite solar cells currently occur at the heterojunction between the charge extraction layers and the perovskite absorber layers. This is the region in the cell where detrimental surface and interfacial charge recombination takes place. The aim of this project is to investigate how tuning the nature of this contact region can supress interfacial recombination and enhance open-circuit voltage and efficiency. Specific efforts will be made to reduce the interfacial contact area between the materials, via the introduction of thin insulating layers. Atomic layer deposition will be a methodology developed during this PhD. Augustin will be specifically refurbishing and upgrading a home-made Atomic Layer Deposition apparatus, for subsequent use in his experiments. Introducing both spatially patterned, and very thin insulating layers in order to reduce the physical contact area between the absorber and charge extraction layer is a methodology which is employed in manufactured silicon solar cells. However, it has not been widely investigated in perovskite solar cells. We expect that this new direction for enhancing the efficiency of perovskite solar cells will lead to a significant increase in efficiency and move the performance of such cells very close to their thermodynamic limits. The direct impact will be to deliver a superior device architecture and concept to currently existing perovskite solar cells. The academic impact will be a number of high profile scientific papers and contribution towards sustaining the academic lead of the Oxford Physics research group. The commercial impact is likely to be transfer of the technological advancements to the industrial partner Oxford PV Ltd. which will increase their technological offering.

This research falls within the EPSRC research areas of Materials for Energy Applications, and Solar Technologies. Oxford PV Ltd. are sponsoring the stipend for Augustin Zaininger and will collaborate throughout the project. They will be supplying some materials and allowing Augustin access to some of their equipment for specific experimental testing. It is very likely, that successful developments within this projects, if patent protected, will be able to be licenced to Oxford PV, through Oxford University Innovations.