TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The semiconductor layer contains microparticles of titanium oxide or tin oxide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (disclosed): A ruthenium transition metal reagent (0.5-50 mol) and 2,2':6',2''-terpyridine-4,4',4''-tricarboxylic acid (1 mol) are refluxed in solvent, reacted at 50-150 degrees C for 12-48 hours, phenyl bipyridyl ligand of formula (17) is added, refluxed and purified, to obtain pyridine-type metal complex of formula (41). Preferred Compounds: The pyridine-type metal complex having partial structure is of formula: ML1(L4)2, ML1L3L4, ML1L5X, ML2L5 or (12, preferably 29-32, more preferably 29, 13, preferably 33-36, more preferably 33, 14, preferably 37-40, more preferably 37, and 15, preferably 41-42, more preferably 41).L1=phenyl pyridyl ligand, preferably of formula (16);L2=phenyl bipyridyl ligand, preferably (17);L3=bidentate bipyridyl ligand having substituent (D'-R-), 1-20C alkyl optionally having substituent, 2-10C alkenyl, alkynyl, 6-10C aryl, heteroaryl, 7-13C arylalkyl or heteroarylalkyl, group of formula (18),;L4=bidentate pyridyl ligand having substituent (A), preferably 2,2'-bipyridine-4,4'-dicarboxylic acid, 1,10-phenanthroline-4,7-dicarboxylic acid, 2-(4-carboxypyridin-2-yl)quinoline-4-carboxylic acid or 2,2'-biquinoline-4,4'-dicarboxylic acid;L5=trivalent pyridyl ligand having substituent (A);substituent (A)=carboxy, sulfonic acid, hydroxy, hydroxam acidic radial, phosphoryl or phosphonyl;X=monovalent ligand having acyloxy, acylthio, thioacyloxy, thioacylthio, acylaminooxy, thiocarbamate, dithiocarbamate, thiocarbonate, dithiocarbonate, trithiocarbonate, acyl, thiocyanate, isothiocyanate, cyanate, isocyanate, cyano, alkylthio, arylthio, alkoxy or aryloxy, or monovalent ligand having halo, carbonyl, dialkyl ketone, 1,3-diketone, carbamide, thiocarbamide, thiourea or isothiourea, preferably 2,2':6',2''-terpyridine-4,4',4''-tricarboxylic acid, 2,2':6',2''-terpyridine-4,4'-dicarboxylic acid, 2,2':6',2''-terpyridine-4,4''-dicarboxylic acid, 2,2':6',2''-terpyridine-4'-carboxylic acid, 2,2':6',2''-terpyridine-4,4',4''-triphosphoric acid or 2,2':6',2''-terpyridine-4,4'-diphosphoric acid;M=ruthenium, iron, osmium, copper, tungsten, chromium, molybdenum, nickel, palladium, platinum, cobalt, iridium, rhodium, rhenium, manganese or zinc;R1-R7=H, halo, 1-20C alkyl, 2-10C alkenyl, alkynyl, 6-10C aryl, heteroaryl, 7-13C arylalkyl or heteroarylalkyl;D1=group of formula (16);D2-D5=group of formula (17);andD6,D7=D'. EXAMPLE - 2-(2'-Methylphenyl)-4-methylpyridine, lithium diisopropylamide and tetrahydrofuran were reacted at -78 degrees C for 30 minutes, tetrahydrofuran solution of 2-bromo-5-(5-hexylthiophene-2-yl)thiophene was added, stirred for 6 hours, heated at room temperature, water and dichloromethane were added and purified, to obtain 4-(5'-hexyl-(2,2')bithiophenyl-5-yl)-2-(3-(5'-hexyl-(2,2')bithiophenyl-5-yl)-phenyl)-pyridine. Then, the obtained 4-(5'-hexyl-(2,2')bithiophenyl-5-yl)-2-(3-(5'-hexyl-(2,2')bithiophenyl-5-yl)-phenyl)-pyridine was added into a reaction system, refluxed for 24 hours and purified, to obtain ruthenium complex of formula (50).