TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The first comonomer repeat unit comprises a phenyl moiety of formula (I). The second comonomer repeat unit comprises a benzodithiophene moiety of formula (II), a benzodithiophene moiety of formula (III), a cyclopentadithiazole moiety of formula (IV), a benzothiadiazole moiety of formula (V), a thiadiazoloquinoxaline moiety of formula (VI), a benzoisothiazole moiety of formula (VII), a benzothiazole moiety of formula (VIII), a dibenzosilole moiety of formula (IX), a thienothiophene moiety of formula (X), a thienothiophene moiety of formula (XI), a carbazole moiety of formula (XII), a dithienothiophene moiety of formula (XIII), a tetrahydroisoindole moiety of formula (XIV), a fluorene moiety of formula (XV), a silole moiety of formula (XVI), a cyclopentadithiophene moiety of formula (XVII), a thiazole moiety of formula (XVIII), a thiazolothiazole moiety of formula (XIX), a naphthothiadiazole moiety of formula (XX), a thienopyrazine moiety of formula (XXI), a silacyclopentadithiophene moiety of formula (XXII), an oxazole moiety of formula (XXIII), an imidazole moiety of formula (XIV), a pyrimidine moiety of formula (XXV), a benzoxazole moiety of formula (XXVI), a benzimidazole moiety of formula (XXVII), a pyridopyrazine moiety of formula (XXVIII), a pyrazinopyridazine moiety of formula (XXIX), a pyrazinoquinoxaline moiety of formula (XXX), a thiadiazolopyridine moiety of formula (XXXI), a thiadiazolopyridazine moiety of formula (XXXII), a benzooxadiazole moiety of formula (XXXIII), an oxadiazolopyridine moiety of formula (XXXIV), an oxadiazolopyridazine moiety of formula (XXXV), a benzoselenadiazole moiety of formula (XXXVI), a benzobisoxazole moiety of formula (XXXVII), a benzobisoxazole moiety of formula (XXXVIII), a thienothiadiazole moiety of formula (XXXIX), a thienopyrroledione moiety of formula (XXXX), a tetrazine moiety of formula (XXXXI), a pyrrolopyrroledione moiety of formula (XXXXII), a benzotriazole moiety of formula (XXXXVII), or a benzodithiophene moiety of formula (XXXXVIII). The polymer further comprises: a third comonomer repeat unit different from the first and second comonomer repeat units, where the third comonomer repeat unit comprises the moieties of (I)-(XXXXII) as above per se, a thiophene moiety of formula (XXXXIII), a selenophene moiety of formula (XXXXIV), a thiadiazole moiety, a quinoxaline moiety of formula (XXXXVI), (XXXXVII) and (XXXXVIII), or a furan moiety of formula (XXXXIX); and a fourth comonomer repeat unit different from the first, second, and third comonomer repeat units, where the fourth comonomer repeat unit comprises (X), (XI), (XVIII), (XXXXIII)-(XXXXV) or (XXXXIX) as above per se. The polymer is of formula ((-D1-X(D1)m(-T1)p-A1-(-T1)p)n), preferably poly(4-(5-(4-(7,7-bis-(2-ethyl-hexyl)-7H-3,4-dithia-7-sila-cyclopenta(a)pentalen-2-yl)-2,3,5,6-tetrafluoro-phenyl)-7,7-bis-(2-ethyl-hexyl)-7H-3,4-dithia-7-sila-cyclopenta(a)pentalen-2-yl)-benzo(1,2,5)thiadiazole), poly(1,4-bis(4,4'-bis(2-ethylhexyl)dithieno-(3,2-b:2',3'-d)silole)-2,3,5,6-tetrafluorobenzene-alt-2,5-bis(3-tetradecyl-2-thienyl)-thiazolo(5,4-d)thiazole), or poly-2-(5-(10-(4-(7,7-bis(2-ethylhexyl)-3,11-dithia-7-silatricyclo(6.3.0.02,6)undeca-1(8),2(6),4,9-tetraen-4-yl)-2,3,5,6-tetrafluorophenyl)-7,7-bis(2-ethylhexyl)-3,11-dithia-7-silatricyclo(6.3.0.02,6)undeca-1(8),2(6),4,9-tetraen-4-yl)-4-chloro-3-tetradecylthiophen-2-yl)-5-(4-chloro-3-tetradecylthiophen-2-yl)-(1,3)thiazolo(5,4-d)(1,3)thiazole.R1-R4 = H, halo, or 1-4C trihaloalkyl, preferably F;X, Y1 = CH2, O or S; eitherR5-R8 = H, halo, 1-24C alkyl, 1-24C alkoxy, aryl, heteroaryl, 3-24C cycloalkyl, 3-24C heterocycloalkyl, CN, OR, COR, COOR, or CON(RR1a), preferably H, C8H17 alkyl or COOC12H25; andR5, R6 = H, Cl or C14H29; orR7, R8 = H;R, R1a = H, 1-24C alkyl, aryl, heteroaryl, 3-24C cycloalkyl or 3-24C heterocycloalkyl;R9, R10 = H, 1-24C alkyl, aryl, heteroaryl, 3-24C cycloalkyl or 3-24C heterocycloalkyl;m = 0 or 1, preferably 1;p = 0-2, preferably 0 or 1;n = greater than 1;X = phenyl moiety substituted with 2-4 halo or 2-4 1-4C trihaloalkyl;D1 = benzodithiophene moiety, carbazole moiety, fluorene moiety, cyclopentadithiophene moiety or silacyclopentadithiophene moiety (preferred);A1 = cyclopentadithiazole moiety, benzothiadiazole moiety, thiadiazoloquinoxaline moiety, benzoisothiazole moiety, benzothiazole moiety, thienothiophene moiety, tetrahydroisoindole moiety, thiazole moiety, thiazolothiazole moiety, naphthothiadiazole moiety, thienopyrazine moiety, oxazole moiety, imidazole moiety, pyrimidine moiety, benzoxazole moiety, benzimidazole moiety, pyridopyrazine moiety, pyrazinopyridazine moiety, pyrazinoquinoxaline moiety, thiadiazolopyridine moiety, thiadiazolopyridazine moiety, benzooxadiazole moiety, oxadiazolopyridine moiety, oxadiazolopyridazine moiety, benzoselenadiazole moiety, benzobisoxazole moiety, thienothiadiazole moiety, thienopyrroledione moiety, tetrazine moiety, pyrrolopyrroledione moiety, thiophene moiety, selenophene moiety, thiadiazole moiety, quinoxaline moiety, benzotriazole moiety, or furan moiety; andT1 = thienothiophene moiety, thiazole moiety, thiophene moiety (preferred), selenophene moiety, thiadiazole moiety, or furan moiety.Provided that at least two of R1-R4 is halo or 1-4C trihaloalkyl.