Fig. 1. Comparison of the EQEmax and the voltage loss between E g/q and the V oc for different types of organic solar cells. The grey line indicates the empirical limit for the maximum EQE possible for a given voltage loss given by Li et al. 4 The blue and violet lines are determined using the result in the current work. Traditionally, there are no cases of EQEmax > 0.7 with a voltage loss <0.6 V. Recent results presented here as well as the results from Kawashima and Yan et al. 5,10 show that non-fullerene acceptors are promising candidates to overcome this barrier.
