NOVELTY - A two-dimensional dihydrobenzofuran conjugated polymer (I) is new.    USE - A two-dimensional dihydrobenzofuran conjugated polymer (I) is used in preparing thin film semiconductor device, electrochemistry device, photovoltaic device and photoelectric device, where the device is polymer solar battery device or photodetector device, and the polymer solar battery device is the polymer solar battery device including bulk heterojunction structure (claimed). It is also useful in high mobility field-effect tube field.    DETAILED DESCRIPTION - A two-dimensional dihydrobenzofuran conjugated polymer of formula (I) is new.    Ar1, Ar2, Ar'=un-substituted groups or groups including a substituent consisting of ethenylidene, ethynylene, monocyclic arylene, bicyclic arylene, arylene including at least three rings, monocyclic mixed arylene, bicyclic mixed arylene, conjugated unit of mixed arylene including at least three rings, where number of substituent group in the group including substituent in Ar1 and Ar2 is 1 or 2, the substituent group is aryl, 1-30C alkyl or 1-30C alkoxy;    A1, A2, R1, R2=H, 1-30C alkyl, 1-30C alkoxy, cyano, nitro, ester group, aryl, aralkyl, halo, halogenated alkyl, mixed alkyl, alkenyl, aryl substituted by single bond, double bond, tripe bond and the substituent group combined by them;    Ar'=un-substituted groups or group including a substituent consisting of ethenylidene, ethynylene, monocyclic arylene, bicyclic arylene, arylene including at least three rings, monocyclic mixed arylene, bicyclic mixed arylene, conjugated unit of mixed arylene including at least three rings; where the number of substituent group in the group including substituent in Ar' is 1 or 2, and the substituent group is aryl, 1-30C alkyl, 1-30C alkoxy, or two neighboring C on the Ar' group are substituted to form ethylene dioxy together; and    n=5-500.    INDEPENDENT CLAIMS are included for:    (1) preparing the polymer (I);    (2) semiconductor component composed by the polymer (I) and adulterating agent; where the adulterating agent is at least one of fullerene or its derivatives including (6,6)-pheynylC61 methyl butyrate or (6,6)-pheynylC71 methyl butyrate or fullerene including indene;    (3) application of the polymer (I) or the semiconductor component on preparing thin film semiconductor device, electrochemistry device, photovoltaic device and photoelectric device; where the device is polymer solar battery device or photodetector device, and the polymer solar battery device is the polymer solar battery device including bulk heterojunction structure;    (4) photovoltaic device, including a hole collecting layer, an electron collecting layer, a photovoltaic material layer between the hole collecting layer and the electron collecting layer; where the photovoltaic material layer contains the polymer (I) or the semiconductor component; and the photovoltaic device is preferably polymer solar battery device; and    (5) photoelectric device comprising a first electrode, a second electrode divided with the first electrode, and at least one of activity material layer provided between the first electrode and the second electrode; where the activity material layer contains the polymer (I).