Bulk hetero-junction polymer solar cells(BHJ-PSCs)have attracted much attention for their advantages of low cost,light weight and potential flexibility in large area applications and currently,constructing the D-A type alternating polymers have been demonstrated one of the most efficient way to obtain the highly efficient PSCs [1].However,owing to the difficulty of developing well-suited new D and A building blocks,only a limited number of repeat units in D-A type copolymers achieved good photovoltaic performance successfully.