Dual‐Site Cu(II) Metalation in Donor−Acceptor Hydrogen‐Bonded Organic Framework Enables Record High‐Gain Photoelectrochemical Transistor for Ultrasensitive Biosensing

Abstract

ABSTRACT The pursuit of high current gain (Δ I DS /Δ I GS ), as one of the key figures of merit for benchmarking the performance of photoelectrochemical transistor (PECT), has been ongoing, but to date, the research remains underdeveloped. The interplay between light and innovative materials has been demonstrated as the cornerstone for successful optoelectronic applications. Herein, we report the design and synthesis of hydrogen‐bonded organic framework (HOF) featuring dual‐site (DS) Cu(II) within a donor–acceptor (D−A) architecture, which affords record high‐gain of 4.7 × 10 5 in PECT. This ground‐breaking performance can be attributed to reduced work function and electron‐deficient atomically dispersed DS Cu(II) metalation at the porphyrin center and the diaminotriazine motif, which facilitates efficient intermolecular charge transfer, as evidenced by x‐ray absorption fine structure spectroscopy and density functional theory calculations. Linking with the acidolysis‐triggered Cu(II) in aptasensing, the device achieves the limit of detection down to 6.6 fg mL −1 for highly sensitive detection of tetrodotoxin in real sample, which surpasses those reported in previous studies by three orders of magnitude.