The present invention provides thermoelectric composite materials that comprises a donor-acceptor based conjugated polymer of Formula I and carbon nanotube  structures. Further thermoelectric composite materials doped with p-type dopant and thermic fusing the doped thermoelectric composite materials for superior  thermoelectric performance. The overall composition and processing has improved the electrical conductivity and power factor of doped thermoelectric composite  material undertaken thermic fusing. The thermoelectric composite materials are easily processable for flexible thermoelectric devices and an excellent composite  material with stable performance and can be extensively realistic to industrial fabrication.