TECHNOLOGY FOCUS - METALLURGY - Preferred Components: The metal is ruthenium or osmium (preferably ruthenium).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The dye has a number a of acidic groups HA per molecule that can release a proton or, in their deprotonated form A-, can accept a proton, and in step (B) an amount of NR4-OH equimolar to a is added so as to convert the dye into a soluble, preferably water-soluble, form. In step (E), adjusting the pH of the dye solution occurs by addition of base or acid. The dye is cis-bis(isothiocyanato) bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II) (red dye), and where in step (B), 4 equivalents Of NR4-OH to the amount of red dye is added. The dye is cis-bis(isothiocyanato) bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II) bis-tetrabutylammonium (2TBA-red dye), where in step (B), 2 equivalents of NR4-OH to the amount of 2TBA-red dye is added. The dye is tris(isothiocyanato)-ruthenium(II)-(2,2':6',2''-terpyridine-4,4',4''-tri-carboxylato) tris-tetrabutylammonium salt (3TBA-black dye), where in step (B), 1 equivalent of NR4-OH to the amount of 3TBA-black dye is added. The steps b1) and c1) are performed at greater than 100 (preferably greater than 140, especially 150-180) degrees C and preferably under inert atmosphere and exclusion of light. The dye purified by the method shows HPLC-purity higher than 99%. The dye is purified by the method (M1) and is characterized by a HPLC trace as given in the specification, using the following conditions: column material: reversed phase (preferably C18 or C8 eluent: mixture of alcohol, such as ethanol or methanol/water or acetonitrile/water at pH 7-11 (preferably 9-11) and preferably also by a UV-Vis spectrum as given in the specification. The evaporation occurs by freeze-drying or rotary evaporation. The dye is obtained as solid after evaporation. Preferred Solution: The solvent is ethanol and the pH of the solution at a concentration of 0.3 mM dye is 5-7 (preferably 6.1 plus minus 0.5). The solvent is acetonitrile/tert-butanol and the pH of the solution at a concentration of 0.3 mM dye is of 7-9 (preferably 8.05 plus minus 0.5). Preferred Components: The solvent is a solvent from which, in the manufacture of DSSC, adsorption of the dye to a semiconductor layer of the DSSC is carried out. The solvent is selected from acetonitrile, 1-6C lower alcohol such as methanol, ethanol, propanol, isopropanol, butanol, tert-butanol, or methoxypropionitrile and/or dimethylformamide. The solvent is 1-6C lower alcohol (preferably ethanol) and the pH of the dye-solution is adjusted to 5-7 (preferably 5.9-6.3, especially 6.1 plus minus 0.5), if the dye solution has a dye concentration of 0.1-0.5 (preferably 0.2-0.4) mM, or where the solvent is a 1/1 mixture of acetonitrile/tert-butanol and the pH of the dye-solution is adjusted to 7-9 (preferably 7.9-8.2, especially 8 plus minus 0.5), if the dye solution has a dye concentration of 0.1-0.5 (preferably 0.2-0.4) mM. The base is NR4-OH and the acid is trifluoromethanesulfonic acid, trifluoroacetic acid, nitric acid, acetic acid or sulfuric acid. The dye is a metal-complex having at least one aromatic heterocyclic ligands, the ligand containing at least one nitrogen atom, N, which is linked to the metal. The dye is a compound of formula (NR4)m((HA)a(A)b-Nn)MXp. The dye is a pyridyl complex of ruthenium (preferably a polypyridyl complex of ruthenium).a, b, m, n, p=0-20;n+p=6;m+2=b+p;m=0-12 (preferably 0-4);NR4=tetraalkylammonium or ammonium;R=H or alkyl (preferably 4-12C alkyl);M=metal selected from ruthenium or osmium (preferably ruthenium);X=anion (preferably Cl-, Br-, I-, (CN)-, (NCS)- (preferably (NCS)- with N linked to the metal M);p=0-4 (preferably 2 or 3);HA=acidic group (preferably -COOH, -SO3H or -PO3H2);A=basic group corresponding to the acidic group HA after release of a proton from HA;a=total number of acidic groups HA per dye molecule and is of 1-12 (preferably 1-4, especially 1-2);((HA)a(A)b-Nn)=at least one aromatic heterocyclic ligand (preferably mono- or polycyclic condensed ring system or a system of rings covalently bonded to each other, where, optionally, the ring system or rings are substituted with further substituents, such as halogens or functional groups such as OH, NH2, and/or have further groups R'attached) containing n nitrogen atoms linked to M;n=total number of nitrogen atoms per dye molecule;R'=H, alkyl, aryl, alkoxy, N(R1a)2;andR1a=H or alkyl.The aromatic heterocyclic ligand has a core to which the HA and/or A groups and, optionally, the further above substituents, are attached, which core is selected from pyridine, (2,2')bipyridinyl, 1H-pyrrolo(2,3-b)pyridine, (1,10)phenanthroline, (2,2';6',2'')terpyridine, (3,3')biisoquinolinyl, and 7H-purine. EXAMPLE - A high-quality red dye sensitizer was prepared as follows. The reaction was carried out under inert atmosphere (nitrogen) and exclusion of light. A compound of formula (I) (0.816 mmol) was dissolved in dimethylformamide (DMF) (250 ml) and then compound of formula (II) (3.26 mmol) was added. The mixture was refluxed at 160 degrees C for 8 hours under constant stirring. High excess (80-fold) of NH4NCS (65.2 mmol) was added to the mixture and the reflux continued for another 8 hours. The mixture was cooled down to room temperature and the solvent removed by using a rotary evaporator under vacuum. To the resulting viscous liquid 0.2 M aqueous NaOH-solution (10 ml) was added to give a dark purple-red solution. The solution was filtered, and the pH was lowered to pH 1.7 with an acid solution of 0.5 M HNO3 ( approximately 10 ml) to give a red precipitate. The flask was placed in a refrigerator over night. After the flask was warmed to room temperature, the red solid was collected by filtration. The solid was washed with water acidified to pH 1.7 with HNO3 (3x 20 ml) and washed with diethylether/petrolether 1:1 mixture. The crude product was re-dissolved in 0.2 M aqueous NaOH-solution (10 ml) and filtrated by using water as eluent. The solvent was reduced to a small volume of 10 ml. The product (yield 82%) red dye was obtained by precipitation after addition of 0.5 M HNO3, washing with diethylether/petrolether 1:1 mixture and drying. For converting the red dye into its soluble form 4TBA-red dye 120 mg of it were diluted in water (2 ml), and 4 calculated equivalents of tetrabutylammonium hydroxide (TBA-OH) (0.647 mmol) were added under stirring. 2ml were directly injected into a HPLC column, and the dye was purified in form of 4TBA-red dye by preparative HPLC. The column consisted of RP-C 18 material as stationary phase. As eluent a mixture of methanol or ethanol (solvent A) and water of pH 11 (alkalized by addition of TBA-OH: 8 mmol /1 l water) (solvent B) was used. The dye was transformed from its 4TBA form into the 2TBA-red dye. For that, pure fractions were combined and the volume of the solvent reduced to 5 ml. 0.1 M aqueous trifluoromethansulfonic acid was added very slowly under stirring until a pH value of 4.3-4.4 was achieved. The mixture was then placed in a refrigerator for 12 hours at 4 degrees C. The precipitated product was isolated by filtration, washed with diethylether/petrolether 1:1 mixture and dried to obtain pure isolated sensitizer dye.