NOVELTY - As semi-conducting compound of type N in a photovoltaic substrate, a perylene type compound is used, where the photovoltaic substrate comprises perylene type compound, and a semi-conducting compound of type P, providing, in combination with each other, a photovoltaic effect.    USE - As semi-conducting compound of type N used in a photovoltaic substrate (claimed).    ADVANTAGE - The semi-conducting organic compound of type N has greater photovoltaic effect than that of semi-conducting organic compounds of type N, known up to now, when it is used in combination with a semi-conducting organic compound of type P. The compounds (I), for which the nitrogen atoms are not substituted with aromatic groups, but on the contrary with a hydrogen atom or a non-conjugated group with nitrogen atom, have a semi-conducting nature of type N particularly suitable for an application in photovoltaics. The organic semi-conducting compounds (I) are more flexible, mechanically, and therefore less fragile, than the first and second generation systems. Moreover, they are more lightweight and are further easier to make and prove to be less expensive.    DETAILED DESCRIPTION - As semi-conducting compound of type N in a photovoltaic substrate, a perylene type compound of formula (I) is used, where the photovoltaic substrate comprises (I) and a semi-conducting compound of type P, providing, in combination with each other, a photovoltaic effect.    R and R'=H or 1-36C hydrocarbon group non-conjugated with the nitrogen atom to which it is bound (preferably group of formula -Alk-Ar, or linear or branched 2-24C alkyl group of formula -Alk');    Alk=1-12C alkylene radical;    Ar=optionally substituted 6-10C aryl or optionally substituted 1-10C heteroaryl;    R1-R4, and R'1-R'4=R1a, -NR1aR1b, -OR1a, -CN, -CO2R1a, -NO2, -CH(CN)2 or halo;    R1a and R1b=H or 1-12C alkyl.    An INDEPENDENT CLAIM is included for new perylene type compound having formula (I), excluding 2,9-bis-(4-methoxy-benzyl)-anthra(2,1,9-def;6,5,10-d'e'f')diisoquinoline-1,3,8,10-tetraone; 2,9-dimethyl-anthra(2,1,9-def;6,5,10-d'e'f')diisoquinoline-1,3,8,10-tetraone; anthra(2,1,9-def;6,5,10-d'e'f')diisoquinoline-1,3,8,10-tetraone; and 2,9-diphenethyl-anthra(2,1,9-def;6,5,10-d'e'f')diisoquinoline-1,3,8,10-tetraone.