Simultaneously Realizing Signal‐Switchability and Ultrahigh‐Gain in a Graphene Photoelectrochemical Transistor Toward High‐Performance Biological Detection

Abstract The nascent graphene photoelectrochemical transistor (GPECT) has exhibited promising as a high‐gain detection platform. Here, the simultaneous realization of signal‐switchability and ultrahigh‐gain in GPECT and its application for high‐performance biological detection is reported. It is observed that the photogating by ultraviolet‐reduced graphene oxide (U‐GO) in GPECT could achieve an ultrahigh gain of 1.7 × 10 5 . Moreover, the in situ polymerization of poly(catechol) upon the U‐GO could induce the anodic‐to‐cathodic signal‐switching in the channel current, which is due to reversal photoinduced gate voltage. By integrating with the enzymatic production of catechol in a sandwich immunorecognition, the as‐developed device realized the sensitive detection of carbohydrate antigen 125 with a detection limit as low as 0.004 mU mL −1 . This work features a high‐performance graphene bioelectronic detection and extends the boundaries of existing photoelectrochemical transistor technology.