TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The process further comprises an optional additional step (c) of heat treatment of the solid coating obtained from the step (b). Preferred Components: The concentration of each of compounds CP and CN in the solvent S0 is 0.1-5 mass% with respect to the mass of the solution before the implementation of the step (b). The organic semiconductor compound CN of N-type is fullerene derivatives, preferably (6.6)-phenyl-C61- butyrate of methyl (PCBM). The organic semiconductor compound CP of P-type is polythiophene derivatives, preferably poly(3-hexylthiophene) (P3HT). The S1 fraction of the solvent S0 comprises one or more solvents comprising chlorobenzene, dichlorobenzene, trichlorobenzene, benzene, toluene, chloroform, dichloromethane, dichloroethane, xylenes, alpha , alpha , alpha -trichlorotoluene, methylnaphthalene or chloronaphthalene. The S1 fraction of the solvent S0 comprises at least one xylene, preferably at least ortho-xylene. The S2 fraction of the solvent S0 comprises at least one solvent comprising compounds of formula (Y1-E1) (I), (Y1-E2-Y2) (II), (Y1-E3(Y3)-Y2) (III) and (Y1-E4(Y4)(Y2)-Y3) (IV). The fraction S2 comprises one or more solvents comprising: dicarboxylic acid diester compounds of formula (R1-OOC-A-COO-R2); ester amide compounds of formula (R3OOC-A-CONR4R5); diamide compounds of formula (R8R9NOC-A1a-CONR10R11); monoester compounds of formula (A2a-COO-R15); and monoamide compounds of formula (A3a-CONR16R17).E1-E4 = a linear or optionally branched, optionally saturated, optionally aromatic, 1-20C hydrocarbon spacer group, respectively mono-, di-, tri- and tetravalent;Y1-Y4 = a group carrying at least one polar function, optionally capable to make intermolecular associations of dipole-dipole or hydrogen bonding; either R1, R2 = 1-20C alkyl, 1-20C aryl, 1-20C alkylaryl, or 1-20C arylalkyl;group A = a linear or branched divalent alkylene group; andR3 = optionally saturated, linear or branched, optionally cyclic, optionally aromatic, 1-36C hydrocarbon groups; orR2R3 = a ring (optionally substituted and/or optionally comprising a heteroatom);R4, R5 = groups comprising optionally saturated and substituted, linear or branched, optionally cyclic, optionally aromatic, 1-36C hydrocarbon groups;A = a linear or branched divalent 2-12C, preferably 2-4C alkyl group;R9-R12 = linear or branched optionally entirely or partly cyclic 1-6C, preferably 1-4C alkyl group, or phenyl group;A1a = a divalent group of formula (-CH2-CH2-(CHR14)z-(CHR13)x-(CHR14)y-);x = greater than 0;y, z = greater than or equal to 0;R13 = 1-6C alkyl group;R14 = H or 1-6C, preferably 1-4C alkyl group;R15 = linear or branched, cyclic or non cyclic 1-36C, preferably 1-20C alkyl, aryl, alkylaryl or arylalkyl;A2a = 2-6C, preferably 4C alkyl;R16, R17 = linear or branched, cyclic or non cyclic 1-36C, preferably 1-20C alkyl, aryl, alkylaryl, or arylalkyl; andA3a = 2-6C, preferably 4C alkyl.