Investigating Degradation in Perovskite and Perovskite/Silicon Tandem Solar Cells Using Spatially and Spectrally-Resolved Absorptivity

Instability is the one of the main challenges preventing the commercialization of perovskite solar cells. We briefly summarize our recent development of a contactless, nondestructive approach to study degradation across perovskite and perovskite/silicon tandem solar cells. We employ spectrally and spatially-resolved photoluminescence maps of perovskite solar cells to extract their corresponding absorptivity maps at sub-bandgap wavelengths. The sub-bandgap absorptivity reflects real degradation in the perovskite film and is much more robust and sensitive than its optical bandgap and luminescence intensity. The absorptivity maps allow us to study various common factors which induce and accelerate degradation in perovskite solar cells including air and heat exposures and light soaking. Also, we employ the technique to extract the individual absorptivity component from the perovskite layer in a monolithic perovskite/silicon tandem structure.