TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The process is carried out in the presence of catalyst containing palladium. Preferred Components: The weak organic base is selected from carboxylates of alkaline or alkaline-earth metals such as potassium acetate, sodium acetate, cesium acetate, magnesium acetate, calcium acetate, potassium propionate, sodium propionate, cesium propionate, magnesium propionate and/or calcium propionate, carbonates of alkaline or alkaline-earth metals such as lithium carbonate, potassium carbonate, sodium carbonate, cesium carbonate, magnesium carbonate and/or calcium carbonate, and/or bicarbonates of alkaline or alkaline-earth metals such as lithium bicarbonate, potassium bicarbonate, sodium bicarbonate, cesium bicarbonate, magnesium bicarbonate and/or calcium bicarbonate, preferably potassium carbonate. The catalyst containing palladium is selected from compounds of palladium in oxidation state (0) or (II) such as palladium(II) chloride, palladium(II) acetate, bis(dibenzylidene)palladium(0), and/or bis(acetonitrile)-palladium(II) chloride, preferably palladium(II) acetate. Preferred Composition: The molar ratio of the naphthodithiophene compound (II) and the catalyst containing palladium is 100:1 to 100:20, preferably 100:5 to 100:6.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation(Claimed): Preparation of the copolymer containing naphthodithiophene units and diketopyrrolopyrrole units (I) involves reacting naphthodithiophene compound of formula (II) with disubstituted diketopyrrolopyrrole compound of formula (III) to obtain a finished product.W1 = halo atom selected from chlorine, fluorine, bromine, iodine, preferably bromine.Preferred Process: The preparation process is carried out in the presence of a weak organic base, or in the presence of solvent selected from dipolar aprotic organic solvents and/or halogenated aromatic solvents, or in presence of aliphatic carboxylic acid, at a temperature of 80-170 degrees C, preferably 100-150 degrees C for 12-96 hours, preferably 24-72 hours. Preferred Components: The solvent is selected from N,N-dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, N, N-dimethylformamide, chlorobenzene, dichlorobenzene, chloronaphthalene, dichloronaphthalene and toluene. The aliphatic carboxylic acid is selected from pivalic acid, valeric acid, iso-valeric acid, 2-ethylacetic acid and/or trichioroacetic acid. Preferred Composition: The molar ratio of the naphthodithiophene compound (II) and the weak organic base is 1:2 to 1:5, preferably 1:2.3 to 1:4. The molar concentration of the naphthodithiophene compound (II) is 0.01-2 M, preferably 0.02-1 M. The molar ratio of the naphthodithiophene compound (II) and the aliphatic carboxylic acid is 1:0.1 to 1:1, preferably 1:0.2 to 1:0.5.    TECHNOLOGY FOCUS - POLYMERS - Preferred Property: The copolymer has a weight average molecular weight (Mw) of 3000-300000 Daltons, preferably 6000-200000 Daltons. EXAMPLE - No suitable example given.