Bio‐p–n Junction–Derived Bio–Diodes With Opto‐Ionotronic Switching and Rectification Effects

Abstract The advancement of bio‐ionotronics for the brain‐computer interaction necessitates an exploration of the mechanisms of electron‐ion coupled transport in solid state devices. In this study, a bio‐p–n junction composed of n‐type bacteriorhodopsin and p‐type P3HT are proposed. By leveraging electron‐proton synergistic effects, an opto‐ionotronic bio‐diode capable of performing ionotronic switching and rectification functions is fabricated. The switching behavior of the bio‐diode can be controlled both optically and electrically. Under light illumination, the ionotronic bio‐diode exhibits a rectification effect approaching that of an ideal diode, with a reliability of 99% and a rectification ratio of ≈661. Additionally, this bio‐organic composite ionotronic bio‐diode exhibits wide pH responsiveness, good photostability, and high biocompatibility. The proposed opto‐ionotronic bio‐diode can be utilized as a fundamental component in logic circuits, bridging the gap between semiconductor technology and biological systems, and represents a novel paradigm for the advancement of brain‐computer interaction.