Band Bending at CdTe Solar Cell Contacts - Correlating Electro-Optical and X-Ray Photoelectron Spectroscopy Analyses of Thin Film Solar Cells: Article No. 2300073

With the semiconductor bulk properties reaching target values for highly efficient solar cells, efforts are now applied to reduce losses at solar cell interfaces and contacts. We report advances in understanding back contacts in thin film polycrystalline CdTe solar cells, a leading thin film PV technology. By using X-ray photoelectron spectroscopy, Kelvin Probe spectroscopy, time- and energy-resolved photoluminescence, we analyze defects at the back contact. We estimate densities of recombination centers and charged defects that induce near-back-contact band bending, both resulting in recombination losses. Electro-optical and surface analysis characterization results are integrated to a device model, simulating performance of CdSeTe/CdTe solar cell with 902 mV open circuit voltage.