Photo-thermoelectric (PTE) effect in thin films has emerged as a new realm for photo-detection and energy harvesting from readily available sources. Among the materials, conductive polymers were prepared via solution casting polymerization to afford flexible photo-thermoelectric polymer films. These films generated photocurrent accompanied by photothermal effect upon exposure to a light source. The degree of crystallinity of the polymers (DCP) in thin films was enhanced by controlling the polymerization composition and temperature using polymeric surfactant. The photo-thermolectric output and energy conversion efficiency of the PTE films were largely dependent on the DCP. Both PTE and photocurrent output were correlated to DCP, which provided a working mechanism for PTE effect in polymer film. Broad range NIR absorption, photon to heat, and heat to electric conversion have been realized in one transparent film, which could benefit in exploiting invisible NIR sensors and thin film thermal energy harvesting with a simple structure.