Implied Voltage and Current Characterization in Organic Solar Cells using Transient Photoluminescence

Abstract Measuring photoluminescence (PL) of free charge carriers under operation conditions is a valuable tool for characterizing solar cells. However, in organic solar cells, free charge carrier PL is typically obscured by the emission from non‐dissociated excitons. To overcome this, an adaptation of the time‐resolved PL measurement method is introduced that allows for the separate observation of the effects of applied voltage on the PL of excitons and free charge carriers. Using state‐of‐the‐art D18:Y6 and PM6:Y6 organic solar cells (power conversion efficiencies: and ), this study demonstrated: I) the determination of the implied voltage from free charge carrier PL under operation conditions providing insights into transport losses under steady‐state and transient conditions, II) the construction of a PL‐based current‐implied voltage curve revealing implied efficiencies of and ; III) an estimation of the photogenerated current at the maximum power point by combining PL and electroluminescence measurements, showing a reduction compared to the short‐circuit current, and IV) a discussion of possible origins of this reduction, including recombination due to limited transport, electrode‐induced charges and field‐dependent exciton dissociation. The introduced method thus provides a valuable diagnostic tool for identifying both transport and current losses in high‐efficiency organic solar cells.