High sensitivity and air stability in an organic transistor-based biosensor by inserting a CuPc layer

The improved label-free DNA sensor based on pentacene organic thin-film transistors (OTFTs) with high sensitivity and air stability was fabricated by inserting a copper phthalocyanine (CuPC) layer between metal electrodes and pentacene active layer. Compared to the electric signals of devices with bare pentacene layer, one can reasonably infer that the single-stranded DNA (ssDNA) molecules may be well immobilized onto the CuPc/pentacene film surface, as well as not degrading the performance of the DNA sensor. Furthermore, the optimized thickness of the CuPc layer for the electrical response to the ssDNA immobilization was also obtained. As a result, the device with a CuPc layer shows that the sensitivity is slightly improved, and there is no significant initial performance drop after exposure to the ambient for 30 days. CuPc is used as the interfacial layer on pentacene film to enhance the sensitivity and air stability of the OFET-based sensors.