TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No general method for preparation of the compound (I) is given. Preferred Compound: The compound (I) is selected from 17 compounds as given in the specification e.g. compound of formula (II).R 1a-R 24aand R 25-R 31=H, alkyl, fluoroalkyl, alkoxy, amino, cyano, alkenyl, alkynyl, or (hetero)aryl;arc (a)=polycyclic aromatic substituent or a heterocyclic aromatic substituent (preferably naphthalene, anthracene or pyrene);M'=dicoordinate, tricoordinate, tetracoordinate, or hexacoordinate.Preferred Components: The second compound is selected from C 60, C 70, C 84, F 16-copper phthalocyanine (CuPc), 10-perylenetetracarboxylic- bis-benzimidazole (PTCBI), 3,4,9,10- perylene tetracarboxylic dianhydride (PTCDA), 1-(3-methoxycarbonyl)propyl-1-phenyl (6,6) C61 (PCBM) or 3-perylene-3,4;9,10-tetracarboxydiimide (PTCDI) (preferably C 60). The first layer is disposed using solution processing. The first layer comprises more than one of the compound (I). The second compound is disposed in a layer having a thickness of 80-200 nm. The first compound is disposed in combination with at least one polystyrene, chlorobenzene, toluene, methylene chloride, dichloromethane, chloroform, chloronaphthalene, dichlorobenzene, or pyridine. Preferred Definitions:    M=Zn, Pb, Sn, ClAl, SnO, SnCl 2, Pb(OAc), or Sn(OH) 2;    R 1-R 9and R 13-R 21=fused pyrene;    n=0-5.    SPECIFIC COMPOUNDS - 4 Compounds are specifically claimed as the compound (I) comprises (mu-(10,10'-bis(1-pyrenyl)-5,5',15,15'-tetrakis(3,5-di-tert-butylphenyl)-18,18',20,20'-dicyclo-2,2'-biporphyrinato(4-)-kappaN 21,kappaN 22,kappaN 23,kappaN 24, kappaN 21',kappaN 22',kappaN 23',kappaN 24'))dizinc(II) (I'), (mu-(9,10,9',10'-bis(1,10-pyrenyl)-5,5',15,15'-tetrakis(3,5-di-tert-butylphenyl)-18,18',20,20'-dicyclo-2,2'-biporphyrinato(4-)-kappaN 21,kappaN 22,kappaN 23,kappaN 24, kappaN 21',kappaN 22',kappaN 23',kappaN 24'))dilead(II). (mu-(9,10,9',10'-bis(1,10-pyrenyl)-5,5',15,15'-tetrakis(3,5-di-tert-butylphenyl)-18,18',20,20'-dicyclo-2,2'-biporphyrinato(4-)-kappaN 21,kappaN 22,kappaN 23,kappaN 24, kappaN 21',kappaN 22',kappaN 23',kappaN 24'))dizinc(II); and (mu-(9,10,9',10'-bis(1,10-pyrenyl)-5,5',15,15'-tetrakis(3,5-di-tert-butylphenyl)-18,18',20,20'-dicyclo-2,2'-biporphyrinato(4-)-kappaN 21,kappaN 22,kappaN 23,kappaN 24, kappaN 21',kappaN 22',kappaN 23',kappaN 24'))tetrachloroditin(II).    EXAMPLE - (mu-(10,10'-Bis(1-pyrenyl)-5,5',15,15'-tetrakis(3,5-di-tert-butylphenyl)-18,18',20,20'-dicyclo-2,2'-biporphyrinato(4-)-kappaN 21,kappaN 22,kappaN 23,kappaN 24, kappaN 21',kappaN 22',kappaN 23',kappaN 24'))dizinc(II) (65 mg) and anhydrous iron(III) chloride (120 mg) were stirred in anhydrous dichloromethane (50 ml) under nitrogen atmosphere for 2 hours. Reaction mixture was quenched with pyridine (2 ml), washed with water and passed consecutively through pad with silica gel and neutral alumina eluting with dichloromethane to give solution of the crude free base fused porphyrin dimer. Solution of zinc(II) acetate dihydrate (200 mg) in methanol (10 ml) was added to the solution of free-base dimer and the mixture was stirred for 2 hours at room temperature. After work-up (mu-(9,10,9',10'-Bis(1,10-pyrenyl)-5,5',15,15'-tetrakis(3,5-di-tert-butylphenyl)-18,18',20,20'-dicyclo-2,2'-biporphyrinato(4-)-kappaN 21,kappaN 22,kappaN 23,kappaN 24,kappaN 21',kappaN 22',kappaN 23',kappaN 24'))dizinc(II) (40-50 mg, 62-77%) was obtained.