Opto-electronic characterization of third-generation solar cells

In the manuscript we presented transient photocurrent simulations with rise and decay. Here we analyse the same TPC decay in detail. Figure S1 shows simulation results of the transient photocurrent decay for all cases defined in Table 1 in the manuscript. With a lower mobility (b) the decay is slower because it takes longer until the device is empty. In the case ‘deep traps’ (c) the current shows an undershoot (the photocurrent becomes positive). Charges flow back into the device. This reverse current can be explained by looking at the trap occupation. In the dark more traps are filled than under illumination. Illumination leads to a depletion of traps via SRH-recombination. The ‘shallow traps’ (c) lead to an exponentially decaying current caused by thermal emission of the carrier from the traps. Interestingly, the case with an extraction barrier (a) shows a very similar behaviour, as also here an energetic activation governs the slow part of the charge collection.