Charge Extraction and Recombination Dynamics of CdSe/CdTe Solar Cells Studied with Transient Photovoltage/Photocurrent Techniques

Significant advancements have been made in the development of high-performance cadmium telluride (CdTe)-based thin film solar cells. However, studies examining the transient excited-state charge dynamics, which determine the final steady-state device performance, are relatively scarce, particularly under device operando conditions. In this work, we investigated charge recombination and extraction dynamics of CdTe solar cells, in comparison with MAPbI3 and narrow bandgap perovskite-based solar cells, using bias-light intensity-dependent transient photovoltage (TPV) and transient photocurrent (TPC) techniques. We found that trap-assisted recombination is the dominant mechanism in the CdTe device at open-circuit, even at 1 sun illumination. Parameters such as charge density, carrier lifetime, and recombination order were extracted from the TPV/TPC data and successfully used to reproduce the open-circuit voltage and short-circuit current densities of the devices measured at steady-state. Consequently, we conclude that these techniques are effective for characterizing charge recombination and extraction dynamics of CdTe solar cells under operando conditions.