Functional Metal–Organic Frameworks for Maximizing Transconductance of Organic Photoelectrochemical Transistor at Zero Gate Bias and Biological Interfacing Application.

Organic electrochemical transistors showing maximum transconductance (gm) at zero gate bias (VG) is desired but has long been a challenge. To date, few solutions to this issue are available. Light‐matter interplay is shown as rich sources for optogenetics, photodynamic therapy, and advanced electronics, but its potential in gm modulation are largely untapped. Herein, the challenge is addressed by unique light‐matter interplay in the newly emerged technique of organic photoelectrochemical transistor (OPECT), which is exemplified by dual‐ligand photosensitive metal–organic frameworks (DL‐PS‐MOFs)/TiO2 nanorods (NRs) gated poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) OPECT under 425 nm light irradiation. Interestingly, the light stimulation on the DL‐PS‐MOFs can de‐dope PEDOT:PSS with altered transistor physics, achieving device showing maximum gm at zero VG and the simultaneous superior output of channel current. In connection to a cascade catalytic hairpin assembly‐rolling circle amplification strategy, such a device is then biologically interfaced with a miRNA‐triggered growth of DNA spheres for the sensitive detection of miRNA‐21 down to 0.12 fm. This work features a proof‐of‐concept study using light‐matter interplay to enable organic transistors showing maximum gm at zero VG and its sensitive biological interfacing application. [ABSTRACT FROM AUTHOR]