A new type of plastic near-infrared photodetector utilizing low band gap polymer (see figure) is presented. When composing the detector in a donor-acceptor type energy band structure and operating it in the reverse bias condition (less than 5 V), the photodetector shows respectable performance: external quantum efficiency exceeding 38 %, bandwidth of 4 MHz and the noise equivalent power of 3.85 x 10(-12) W Hz(-1/2) at 850 nm.