The present invention relates to the use of mixtures which comprise, as components K1), one or more merocyanines selected from the group of the compounds of the general formulae I, IIa, IIb, IIIa, IIIb, IIIc, IIId and IIIe, as defined in more detail in the description, as an electron donor or electron acceptor, and, as component K2), one or more compounds which, with respect to component K1), act correspondingly as an electron acceptor or electron donor, for producing photoactive layers for organic solar cells and organic photodetectors, to a process for producing photoactive layers, corresponding solar cells and organic photodetectors, and to mixtures which comprise, as components, one or more compounds of the general formulae I, IIa, IIb, IIIa, IIIb, IIIc, IIId and/or IIIe of component K1, as defined in more detail in the description, and one or more compounds of component K2.