Dimitris N. Chorafas Foundation Award 2017 – Konrad Domanski

"For his groundbreaking studies of lead halide perovskite solar cells. His research has identified salient factors that effect the stability of these new photovoltaic devices, in turn allowing to improve their operational stability under real-life conditions."

Perovskite solar cells (PSCs) have attracted substantial interest owing to a very rapid achievement of efficiencies >20 %. However, for any solar cell to become technologically viable, good stability has to be demonstrated additionally. Hence, understanding degradation and improving the lifetimes of PSCs has become the main research topic in the field of emerging photovoltaics. In this thesis, I firstly show how I designed and built a dedicated setup to investigate stability of PSCs. Subsequently, I describe the intrinsic high-temperature instability of state-of-the-art PSCs due to Au diffusion from the electrode. I then show how polymeric hole transporting layers solve this problem. I also present an alternative approach by replacing the Au electrode with one based on carbon nanotubes. Subsequently, I describe the effects of mobile ions on the partially reversible losses in aged PCSs and I show how the ionic movement in the perovskite can allow certain PSCs to work as high-gain photodetectors. Finally, I describe how different factors such as temperature, illumination, atmosphere and load on the device affect the stability of PSCs. Based on this, I propose several PSC stability measurement protocols as an attempt to bring the community to a consensus on how to age PSCs.