NOVELTY - A solar cell comprises a semiconductor charge separation material (m1); at least one electrode connected to the material (m1); and a light-harvesting film on the material (m1). The light-harvesting film comprises non-covalently coupled, self-assembled units of porphyrinic macrocycles having an intramolecularly coordinated metal, first coordinating substituent, and second coordinating substituent opposite the first substituent. The macrocycles are assembled by repeating intermolecular coordination complexes of the metal, the first substituent and the second substituent.    USE - For solar energy conversion.    ADVANTAGE - The porphyrinic macrocycles are exceptionally attractive for use in molecular solar cells, as they have ability to install electron-withdrawing/releasing substituents or auxochromes as specific sites; and are self-assembling porphyrin, and have ability to constrict the macrocycle from simple precursors that provides a great deal of flexibility in the design of molecules suitable for use in solar cells.    DETAILED DESCRIPTION - A solar cell comprises a semiconductor charge separation material; at least one electrode connected to the charge separation material; and a light-harvesting film on the charge separation material. The light-harvesting film comprises non-covalently coupled, self-assembled units of porphyrinic macrocycles. The porphyrinic macrocycles comprise an intramolecularly coordinated metal, a first coordinating substituent, and a second coordinating substituent opposite the first coordinating substituent; and are assembled by repeating intermolecular coordination complexes of the metal, the first coordinating substituent and the second coordinating substituent. INDEPENDENT CLAIMS are included for the following:    (1) new porphyrinic macrocycle compounds of formula (I), or their salts; and    (2) preparation of the solar cell involving coating semiconductor charge separation material with the porphyrinic macrocycle under conditions in which the porphyrinic macrocycle self-assembles to form the light-harvesting film on it; and connecting the at least one electrode to the semiconductor 'p' region before or after the coating step.    M1=a metal;    X1 to X4=Se, NH, CH2, O or S;    X5=O or S;    X6=OH, SH, or NR41R42;    R1 to R8, R11 to R16, R31, R32, R41, and R42=H, alkenyl, alkynyl, (cyclo)alkyl, cycloalkylalkyl, cycloalkylalkenyl, cycloalkylalkynyl, heterocyclo, heterocycloalkyl, heterocycloalkenyl, heterocycloalkynyl, aryloxy, arylalkyl, arylalkenyl, arylalkynyl, (hetero)aryl, heteroarylalkyl, heteroarylalkenyl, heteroarylalkynyl, alkoxy, halo, mercapto, azido, cyano, acyl, formyl, carboxylic acid, acylamino, ester, amide, hydroxyl, nitro, alkylthio, amino, alkylamino, arylalkylamino, disubstituted amino, acyloxy, sulfoxyl, sulfonyl, sulfonate, sulfonic acid, sulfonamide, urea, alkoxylacylamino, aminoacyloxy, surface attachment groups, or auxochromes;    R1+R2, R3+R4, R11+R12, R13+R14=o or spiroalkyl;    R31+R32=O;    R2+R3 and R12+R13=double bond.