The nominal cell operating life of perovskite solar cells is strongly influenced by their inner architecture. This was shown by two scientists at the Helmholtz-Zentrum Berlin and the Technical University of Munich. They combined experiments with numerical simulations in order to explain this observation. Antonio Abate (HZB) and Allessio Gagliardi (TU Munich) explored different architectures of perovskite cells, preparing them under identical conditions using metal-oxide electron transport layers (ETL) such as TiO2 and SnO2. One group of cells had a planar interface between perovskite and ETL, whereas in the other one a mesoporous interface was built up, intermingling perovskite and metal oxide to form a sponge like structure that contains a huge number of extremely tiny pores. The perovskite cell with the mesoporous interface exhibits better output stability over time than the planar ETL-perovskite interface. »The benefit induced by the mesoporous interface is fundamentally due to its large surface area,« Abate explains. Defects that compromise the power output and operating life and which accumulate during operation at the ETL tend to get diluted in this large surface.

The results are published in ACS Energy Lett., (2018): »Mesoporous Electron-Selective Contacts Enhance the Tolerance to Interfacial Ion Accumulation in Perovskite Solar Cells,« A. Abate and A. Gagliardi.