The present invention relates to a formulation comprising at least one solvent and at least two functional compounds of the general formula (I) where A is a functional structural element, B is a solubility-promoting structural element and k is an integer in the range from 1 to 20, the molecular weight of the functional compound is at least 550 g/mol and the solubility-promoting structural element B conforms to the general formula (L-I) where Ar1, Ar2 is each, independently of one another, an aryl or heteroaryl group, which may be substituted by one or more radicals R of any desired type, X is in each case, independently of one another, N or CR2, preferably CH, R1, R2 is each, independently of one another, hydrogen, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms or is a silyl group or a substituted keto group having 1 to 40 C atoms, an alkoxycarbonyl group having 2 to 40 C atoms, an aryloxycarbonyl group having 7 to 40 C atoms, a cyano group (CN), a carbamoyl group (C(═O)NH2), a haloformyl group (C(═O)—X, in which X represents a halogen atom), a formyl group (C(═O)—H), an isocyano group, an isocyanate group, a thiocyanate group or a thio-isocyanate group, a hydroxyl group, a nitro group, a CF3 group, Cl, Br, F, a crosslinkable group or a substituted or unsubstituted aromatic or heteroaromatic ring system having 5 to 60 ring atoms, or an aryloxy or heteroaryloxy group having 5 to 60 ring atoms, or a combination of these systems, where one or more of the groups R1 and/or R2 may form a mono- or polycyclic, aliphatic or aromatic ring system with one another and/or with the ring to which the group R1 is bonded; and l is 0, 1, 2, 3 or 4; where the dashed bond indicates the bond to the functional structural element A. The present invention furthermore relates to electronic devices which comprise mixtures of these compounds.