Perovskite solar cells have electrified the solar cell research community with astonishing performance and surprising material properties. However, the widespread commercialization of perovskites in solar cells and other optoelectronic applications still requires a more detailed knowledge about fundamental material properties. My group is specialized in the investigation of these properties on nanometer length scales using scanning force microscopy.<br/>We recently discovered a distinct nanoscale stripe domain structure in MaPbI<sub>3</sub> perovskite crystals using piezoresponse force microscopy (PFM). The pattern is characteristic for ferro-elastic twin domains. Using a combination of PFM and photoluminescence microscopy, we found that this domain structure leads to an anisotropic charge transport across the crystal. To visualize the functionality of different layers, we developed a method to prepare smooth cuts through a solar cell device. We subsequently map the potential distribution across the device using time-resolved Kelvin probe force microscopy (tr-KPFM). We could show that the formation and release of ionic interface charges determine the time scales for current-voltage hysteresis in perovskite solar cells. Our results highlight that precise control over interfaces in perovskite solar cells is the key, not only for controlling and suppressing hysteresis but also for their long-term stability in perovskite solar cells.

Nanoscale effects in perovskite solar cells observed by scanning force microscopy

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.