Transition Metal Dichalcogenide-Based Heterojunction Band Alignment-Enabled Organic Photoelectrochemical Transistor Biosensing

Organic photoelectrochemical transistors (OPECTs) represent an emerging bioelectronic platform synergizing photoelectrochemical processes with organic electrochemical transistors for amplified transduction of light-matter-bio interactions. However, OPECT performance remains fundamentally constrained by inefficient carrier dynamics at the photogate. To address this, we develop a novel transition metal dichalcogenide (TMD)-based heterojunction photogate by integrating FeSe₂ with ZnIn₂S₄, leveraging band alignment engineering to optimize interfacial charge separation. This work pioneers a H₂O₂-triggered dynamic band modulation strategy within a TMD heterojunction for OPECT biosensing. Surface oxidation of FeSe₂ by H₂O₂ disrupts the original band alignment, forming a new charge migration pathway and enhancing the photovoltage of the gate. Such a change restructures the control behavior of the transistor and ultimately amplifies the channel current response. Linking a prostate-specific antigen (PSA)-targeted proteolytic peptide system and the biological generation of H₂O₂, such a phenomenon was correlated to PSA concentration with good performance in terms of selectivity and sensitivity. This study not only demonstrates the first TMD heterojunction-engineered OPECT for biosensing but also establishes a versatile framework for advancing next-generation bioelectronics through target-responsive interfacial band engineering.