Fig. 7
Charge carrier recombination in NC-FREA solar cells. a Voc as a function of illumination intensity for the solar cells based on different acceptors. Slopes are indicated. b Dark J–V characteristics of the solar cells based on different acceptors. Ideality factors, α, are calculated using the equation: \(J_{{\mathrm{dark}}} = J_0{\mathrm{exp}}\left( {qV/\alpha kT} \right)\), where J0 represents the dark saturation current density
