The invention relates to a polymer comprising structural unit of formula II: wherein R1, R2, R3, R4, R5, R6 and R7 are independently at each occurrence a C1-C20 aliphatic radical, a C3-C20 aromatic radical, or a C3-C20 cycloaliphatic radical; a, b, d, e and f are independently at each occurrence 0, or an integer ranging from 1 to 4; c and g are independently at each occurrence 0, or an integer ranging from 1 to 3. In another aspect, the invention relates to monomers for preparing the polymers. In yet another aspect, the invention relates to an optical electronic device comprising a polymer comprising structural unit of formula II.