The transport mechanism of organic materials is still far away from being well understood and controlled although conducting polymers have been discovered since 1977. It is rare to see conducting polyers possessing high bipolar (p- and n-type) electrical conductivities within a single bulk doped organic polymer without the assistant of gate voltage. Here, we report a novel approach to provide high performance n-type materials by p-type doping. More importantly, the bipolar electrical conductivities of the donor-acceptor conducting polymer are high, resulting high bipolar power factors among the solution-processable ambipolar D-A copolymers. A fully organic p-n junction is created in a planar film, exhibiting a high rectification ratio of 2 x 102 at +5 V with a high current density of 3 A/cm2. Structural and spectroscopic tests have been performed to provide a fundamental understanding of the polarity switching mechanism. The results open the opportunity of making p- and n-type modules with a single conducting polymer for future modern organic electronics.