Passivating Inorganic Interlayers at the Perovskite/C60 Interface in Monolithic Perovskite Silicon Tandem Solar Cells

Metal halide perovskites emerged in recent years as promising absorber materials for solar cells that can combine high power conversion efficiency with low production costs. Significant non-radiative charge carrier recombination occurs at the perovskite interface with the electron contact C60, which prevents the full exploitation of the solar cell’s potential. C60 induces states within the band gap, lowers the quasi-Fermi level splitting, and limits the open circuit voltage (VOC). Ultra-thin passivation layers at the perovskite/C60 interface are used to reduce those losses. To enable industrial upscaling, our focus lies on inorganic passivation layers deposited via atomic layer deposition. An AlOx interlayer was developed that increases the iVOC up to 50 mV and improves theVOC for singlejunction and tandem devices. To better understand the effects involved in this passivation, photoluminescence quantum yield (PLQY), angle-resolved X-ray photoelectron spectroscopy (ARXPS) and surface photovoltage (SPV) measurements were carried out. State-of-the-art perovskite solar cells using a LiFx passivation layer suffer from device degradation over time. Initial stability testing indicates that a thin AlOx passivation layer can improve device stability and can serve as an alternative to LiFx.