TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The first monomer repeat unit includes substituent on a ring consisting of 1-20C alkyl, 1-20C alkoxy, aryl, heteroaryl, 3-20C cycloalkyl, 3-20C heterocycloalkyl, halo, carbon-nitrogen, nitrogen dioxide, or SO2R (i).R=H, 1-20C alkyl, 1-20C alkoxy, aryl, heteroaryl, 3-20C cycloalkyl, or 3-20C heterocycloalkyl.The substituent is 1-20C alkoxy optionally further substituted with 1-20C alkoxy or halo, preferably the substituent is hexyl, ethylhexyl, (OCH2CH2)2OCH3 or OCH2CF2OCF2CF2OCF3.The first monomer repeat unit comprises benzothiadiazole moiety of Formula (II), thiophene dioxide moiety of Formula (VIII), or cyclopentadithiophene tetraoxide moiety of Formula (X).R5, R6=H, 1-20C alkyl, 1-20C alkoxy, aryl, heteroaryl, 3-20C cycloalkyl, 3-20C heterocycloalkyl, halo, CN, NO2, or (i).The photovoltaic cell further comprises a second monomer repeat unit different from the first monomer repeat unit, and comprises cyclopentadithiophene moiety, benzothiadiazole moiety, thiadiazoloquinoxaline moiety, cyclopentadithiophene oxide moiety, benzoisothiazole moiety, benzothiazole moiety, thiophene oxide moiety, thienothiophene moiety, thienothiophene oxide moiety, dithienothiophene moiety, dithienothiophene oxide moiety, tetrahydroisoindole moiety, fluorene moiety, thiophene moiety, or silole moiety. The second monomer repeat unit includes substituent on a ring consisting of 1-20C alkyl, 1-20C alkoxy, aryl, heteroaryl, 3-20C cycloalkyl, 3-20C heterocycloalkyl, halo, CN, NO2, or (i). The second monomer repeat unit comprises cyclopentadithiophene moiety of Formula (I), benzothiadiazole moiety of Formula (II), thiophene dioxide moiety of Formula (VIII), cyclopentadithiophene tetraoxide moiety of Formula (X), fluorene moiety of Formula (XIX), or thiophene moiety of Formula (XX).R1-R6=H, 1-20C alkyl, 1-20C alkoxy, aryl, heteroaryl, 3-20C cycloalkyl, 3-20C heterocycloalkyl, halo, CN, NO2, or (i).    TECHNOLOGY FOCUS - POLYMERS - Preferred Compounds: The polymer is a compound of Formula (P1) or Formula (P2). It is an electron donor material or an electron acceptor material.n=greater than 1.