NOVELTY - A conjugated polymer (I) of perylene tetracarboxylic acid diimide and benzodithiophene, is new.    USE - Conjugated polymer of perylene tetracarboxylic acid diimide and benzodithiophene used for manufacturing solar cells, organic electroluminescent devices and organic field effect transistors (all claimed).    ADVANTAGE - The conjugated polymer of perylene tetracarboxylic acid diimide and benzodithiophene has favorable solubility, strong absorbance, wide light absorption range, improved photoelectric conversion efficiency, and excellent charge transport performance.    DETAILED DESCRIPTION - A conjugated polymer of perylene tetracarboxylic acid diimide and benzodithiophene, of formula (I), is new.    n=positive integer, preferably less than 101;    R1-R3=H, 1-20C alkyl, 1-20C alkoxy phenyl or phenyl;and    R4,R5=1-20C alkyl.    INDEPENDENT CLAIMS are included for the following:    (1) solar cell, which is prepared using conjugated polymer, and comprises a substrate, a conducting layer, a poly(3,4-ethylenedioxythiophene):polystyrolsulfonic acid layer, and conjugated polymer layer with activation and aluminum metal layer;    (2) manufacture of solar cell, which involves washing substrate and depositing a conducting layer on one surface of the substrate, coating poly(3,4-ethylenedioxythiophene):polystyrolsulfonic acid on the conducting layer after surface treatment of the conducting layer to form the poly(3,4-ethylenedioxythiophene):polystyrolsulfonic acid layer, coating the conjugated polymer on the poly(3,4-ethylenedioxythiophene):polystyrolsulfonic acid layer to form the conjugated polymer layer with activation, arranging the aluminum metal layer on the conjugated polymer layer;    (3) organic electroluminescent device, which is prepared using the conjugated polymer, and comprises substrate, conducting layer, luminescent conjugated polymer layer, lithium fluoride buffer layer and aluminum metal layer;    (4) manufacture of organic electroluminescent device, which involves washing substrate and depositing a conducting layer on one surface of the substrate, coating conjugated polymer on the conducting layer after surface treatment of the conducting layer to form the luminescent conjugated polymer layer, evaporating lithium fluoride on the conjugated polymer layer;    (5) organic field effect transistor, which is prepared using the conjugated polymer, and comprises doped silicon substrate, silicon dioxide insulating layer, octadecyltrichlorosilane layer, organic semiconducting layer of conjugated polymer, metallic source electrode and drain electrode; and    (6) manufacture of organic field effect transistor, which involves washing doped silicon substrate and depositing the silicon dioxide insulating layer, coating octadecyltrichlorosilane on the silicon dioxide insulating layer to form the octadecyltrichlorosilane layer, coating the conjugated polymer on the octadecyltrichlorosilane layer to form the organic semiconducting layer of conjugated polymer, and arranging the metallic source electrode and drain electrode on the organic semiconducting layer of conjugated polymer.