ZnO Single-Crystal-Driven Organic Photoelectrochemical Transistors for Improved Human Thrombin Detection

Organic photoelectrochemical transistors (OPECTs) offer a promising platform for investigating light-matter interactions in biological systems. However, conventional photosensitive gate materials, such as quantum dots, metal oxides, and heterojunctions, suffer from limitations, including cytotoxicity, low light conversion efficiency, and interface instability. To overcome these challenges, this study introduces single-crystal ZnO (SC-ZnO) as an ideal photogate material. The defect-free lattice structure of SC-ZnO enhances charge separation, reduces the dark current, and improves the chemical stability. We developed an OPECT biosensor by functionalizing thrombin specific aptamers on SC-ZnO/Au NPs. The binding of thrombin regulates the potential at the gate electrolyte interface, thereby converting the light signal into an amplified drain current (I_DS) variation. This OPECT-based strategy not only demonstrates a label-free, low-power, and highly sensitive method for thrombin detection but also lays the groundwork for fabricating highly stable photoresponsive, single-crystal-driven OPECT sensors for enhanced biodetection.