Polyoxometalates: Cascading Functionality to Unique On‐Off Organic Photoelectrochemical Transistor Operation

While existing polyoxometalates (POMs) are predominantly utilized in a range of energy devices, their potential in bioelectronics and optoelectronics, particularly in organic photoelectrochemical transistors (OPECTs), remains unexplored. Here, the potential of POMs in this aspect is unveiled by a POM/sulfide‐gated OPECT. The representative PW12/ZnIn2S4 with cascading light‐harvesting and enzyme‐like functionality enables unique on‐off OPECT operation. The incorporation of PW12 facilitates the separation of photogenerated charge carriers across the heterojunction interface, consequently inducing a pronounced gating effect. Linking with a CRISPR/Cas13a system correlating the target miRNA‐21 and biological generation of H2O2, the PW12 will enable the polymerization of dopamine into polydopamine and thus sensitively inhibit the OPECT gating. Experimental results demonstrated that the developed OPECT sensor achieved good analytical performance with a detection limit as low as 3.9 fm. This study demonstrates the potential of POMs in OPECT. Given the large family and multifunction of POMs, its implications in the diverse bioelectronics and optoelectronics are expected. This study explores the potential of polyoxometalates (POMs) in organic photoelectrochemical transistors (OPECT). The developed PW12/ZnIn2S4 demonstrates cascading light‐harvesting and enzyme‐like functionalities, enabling unique on‐off OPECT operation for representative miRNA biosensing via integration with a CRISPR/Cas13a system. This work is anticipated to catalyze the POM studies in diverse bioelectronics and optoelectronics.