NOVELTY - A 3,8-dioxa-dicyclopenta(a,f)naphthalene-type two-dimensional semiconductor conjugated polymer (I) is new.    USE - New 3,8-dioxa-dicyclopenta-naphthalene-type two-dimensional semiconductor conjugated polymer used for photovoltaic device.    ADVANTAGE - 3,8-Dioxa-dicyclopenta-naphthalene-type two-dimensional semiconductor conjugated polymer having narrow molecular weight distribution and containing rigid large ( pi )-conjugated system, is prepared efficiently and economically by simple method.    DETAILED DESCRIPTION - A 3,8-dioxa-dicyclopenta(a,f)naphthalene-type two-dimensional semiconductor conjugated polymer of formula (I) is new.    n=more than 1 and less than 50.    An INDEPENDENT CLAIM is included for preparation of 3,8-dioxa-dicyclopenta(a,f)naphthalene-type two-dimensional semiconductor conjugated polymer (I). In presence of potassium carbonate as catalyst and N,N-dimethylformamide as solvent, 1,5-dihydroxynaphthalene and brominated diethyl acetal are reacted to obtain 1,5-Bis-(2,2-diethoxy-ethoxy)-naphthalene (I). In presence of methylene chloride as solvent, the obtained compound (I) reacts with N-bromosuccinimide to obtain 1,5-dibromo-4,8-bis-(2,2-diethoxy-ethoxy)-naphthalene (II). The obtained compound (II) is subjected to ring closure reaction in presence of polyphosphoric acid as catalyst and methylene chloride as solvent to obtain 4,9-dibromo-3,8-dioxa-dicyclopenta(a,f)naphthalene (III). The obtained compound (III) reacts with 4,5-didecyl-2-tri-n-butyltin-thiophene in presence of dichloro bis(triphenylphosphine)palladium as catalyst and toluene as solvent under nitrogen atmosphere to obtain 16-(3,4-bis(decyl)cyclopenta-1,3-dien-1-yl)-8-(4,5-bis(decyl)thiophen-2-yl)-3,11-dioxatetracyclo(7.7.0.02,6.010,14)hexadeca-1,4,6,8,10(14),12,15-heptaene. The resultant compound sequentially reacts with n-butyl lithium or trimethyl tin chloride to obtain (16-(4,5-bis(decyl)thiophen-2-yl)-8-(4,5-dimethylthiophen-2-yl)-12-(trimethylstannyl)-3,11-dioxatetracyclo(7.7.0.02,6.010,14)hexadeca-1,4,6,8,10(14),12,15-heptaen-4-yl)trimethylstannane.