Impact of interfaces on perovskite solar cell’s stability

International audiencePerovskite solar cells represent the most promising concept of solar cells. They combine high efficiency with a strong potential for low cost and good versatility. The main current challenge concerns a lack of stability. The degradation mechanisms of perovskite solar cells have already been studied in details with numerous architectures. It appears that the bulk active layer, the hole and electron transporting layers (HTL and ETL), and each of their interfaces undergo undesirable changes with time. The experimental investigations of the interactions between materials on the stability of a complete device are scarce. The objective of this study is to track the interfaces and the interactions between materials in the stack to reveal the degradation mechanisms. The approach developed relies on the use of partial devices to chase the intrinsic weaknesses of each component, and the possible incompatibility of the interfaces. The current study focuses on the evaluation of the stability of perovskite solar cells, with NIP architectures. Three cases have been selected to show the impact of ETL, HTL and metallic electrode on the degradation of PSCs. The first two studies were performed on a simple perovskite: MAPbI3-xClx monocation formulation, and the devices were submitted in relatively mild ageing conditions (35°C, under dark and inert conditions). In the third case, a multiple anions and cations perovskite was chosen: FA1-xCsxPb(I1-yBry)3, known for its higher initial performances and improved thermal stability. Consequently, more severe aging conditions have been tested (C1:85°C/0%O2/0% RH; C2: 85°C/1% O2/0% RH, C3: 85°C/21% O2/ 40% RH)