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

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.