Photoluminescence Excitation Spectroscopy of Monolithic Perovskite/Silicon Tandem Solar Cells

The contributions of each subcell to the total photoluminescence (PL) spectrum of a monolithic perovskite/silicon tandem solar cell are distinguished using a variable wavelength excitation laser source. In the results, a strong overlap of the PL spectrum is shown, originating from the sub-bandgap region of the perovskite top cell with the emission from the silicon bottom cell, even with near-infrared excitation wavelengths. Consequently, an excitation laser wavelength of at least 815 nm is required for a dominant PL signal from the silicon bottom cell, and a wavelength no longer than 750 nm is needed for a dominant PL signal from the perovskite top cell in the investigated tandem solar cell. Moreover, a shoulder in the sub-bandgap emission of the perovskite top cell almost coincides with the PL response region of the silicon bottom cell, which can cause signal confusion in subcell characterization.