Block conjugated polymer, and preparation method and use thereof

The invention provides a block conjugated polymer used for preparing a high-efficiency organic photovoltaic device, and a preparation method thereof. The block conjugated polymer has a structure shown in a formula I, wherein Ar represents an aromatic ring unit, with the aromatic structure of benzene, thiophene, fluorene, carbazole, silicon-aromatic heterocyclic ring or thiazole heterocyclic ring, of a main polymer chain; R1 and R2 are substitution radicals of [1,2,5]thiadiazole[3,4-g]quinoxaline and diazosulfide respectively, and each of R1 and R2 has one of the structures of hydrogen atom, saturated alkane, double-bond alkane, triple-bond alkane, ether-oxygen chain, alkyl-chain amine and sulphydryl; m and n are numbers of structure-repeated units of the main polymer chain; the summation of m and n is an integer more than or equal to 4; and m is more than or equal to 0, while n is more than or equal to 0. The polymer has the characteristics of better matching with solar spectrums, steric hindrance reduction, crystallization property improvement, and vast application prospect on photoelectric functional devices, particularly on polymer solar cells.