“…The emergence of a first quadrant IMPS feature is rather unique to organic solar cells and underlying kinetic information surrounding trap-mediated recombination, and carrier extraction can be inferred from the positive imaginary photocurrent signal. ,,, In particular, the maximum frequency of Im[Pc] in the low-frequency regime (i.e., ω max Im ) has been related to the rate constant of interfacial, nongeminate charge recombination, k rec . ,,, Importantly, this relationship assumes that recombination is a first-order process consistent with expectations from the Shockley–Read–Hall mechanism of trap-assisted charge recombination. ,, However, some studies have shown that higher-order processes can become important that also vary with temperature and active layer morphology. ,,, It is possible to deduce the nature of these mechanisms by varying the total excitation intensity and the AC modulation depth, where k rec should not change if a purely linear process dominates this signature . This condition may be readily assessed using ω max Im from IMPS to estimate the recombination rate constant that has been confirmed using intensity-modulated photovoltage spectroscopy (IMVS), where no carrier extraction is possible and responses only reveal charge accumulation and recombination .…”