Fig. 8. Plots of the emission intensity (a) at 550 nm (λ_ex = 375 nm) and (b) at 670 nm (λ_ex = 500 nm) as a function of time after exposing a film prepared from a 1 : 1 mixture of C₃OPV and C₃PBI to the vapour of aromatic amines and nitroaromatics, respectively.