Perovskite surface photo-voltage

Project summary :

Nowadays silicon cell technologies represent the largest part of the photovoltaic (PV) panel market (>90%). The solar conversion efficiency of silicon panels has increased over time, while the cost per kWh has decreased more than a factor of 30 since the early 1990s. However, although reliable Si-based PV systems are commercially available and widely applied, such single-junction devices are thermodynamically limited to a theoretical threshold of ~30 % efficiency, called the Shockley-Queisser limit. Therefore, to increase the solar conversion efficiency further development of the PV technology is needed, which will enable PV to become a major source of sustainable energy. Special attention in this regard is paid to next-generation PV technologies based on perovskite materials. Perovskite PV modules and perovskite/Si tandem modules are among the emerging technologies aiming at higher efficiencies and lower costs. This is due to the tunable bandgap via compositional engineering, high absorption coefficient and steep absorption edge of the perovskite materials. 

However, the perovskite based structures suffer from poor knowledge on material and interface properties and are facing stability issues. These cannot be addressed properly without better assessment of the material and interface properties. The proposed project is precisely addressing these issues. The novelty of the work lies in the combination of several modern characterization techniques - Surface Photovoltage (SPV) in DC and AC illumination modes, Kelvin Probe Force Microscopy (KPFM) and KPFM-SPV - together with modelling and simulation activities to achieve a detailed quantitative assessment of the perovskite material and obtain a better understanding of the role of interface vs bulk properties. The carrier extraction mechanisms at the perovskite interfaces and their impact on solar cell performance will be investigated. Comparing experimental and modelling results we have the ambition to achieve a unified picture of the information provided by the SPV technique in its different modes since the interpretation of the available SPV and KPFM data is still questionable and needs appropriate analysis with the help of a proper simulation of the experiment. Eventually, this will help improving the diagnostic of perovskite materials and structures and optimizing these structures for enhanced photovoltaic efficiency.