Perovskite solar cells are the new hope of next-generation photovoltaic concepts for
sustainable energy generation. Regarding their favorable optoelectronic properties bound
electron-hole pairs (so-called excitons) play a significant role and are thoroughly
investigated utilizing various spectroscopic methods. Moreover bandgap instabilities caused by
segregation effects in mixed perovskites are analyzed in detail using electroreflectance
spectroscopy and structural characterization techniques.
