By tailoring the neighboring-conductive-channel organic layer using a plasma-assisted-interfacial-grafting method, we introduced a molecular antenna onto the surface of organic transistors to enable direct interaction between the semiconductors in the conductive channel and the target analytes in solution. The specific interaction provides the OTFT with sensitive adenosine triphosphate (ATP) detection ability, which represents a step forward toward low-cost, flexible, and high throughput organic electronic biosensors.