We demonstrate a novel DNA detection method with low-cost and disposable advantages by utilizing F16CuPc/CuPc planar organic heterojunction device. Single-stranded DNA (ssDNA) molecules have been well immobilized on the surface of CuPc film observed by atomic force microscopy, producing an obvious electrical response of the device. The conductivity of the organic heterojunction film was significantly increased by ssDNA immobilization because ssDNA molecules brought additional positive charges at heterojunction interface. Furthermore, the thickness dependence of CuPc upper layer on the electrical response was studied to optimize the sensitivity. This study will be helpful for the development of organic heterojunction based biosensors. (C) 2016 Elsevier Ltd. All rights reserved.