Heterojunction-gated organic photoelectrochemical transistor for sensitive detection of chlorpyrifos

Chlorpyrifos (CPF) is one of the representative organophosphorus pesticides (OPs) that posing huge risks to both human health and ecological integrity. Building a highly sensitive detection platform to achieve accurate detection of trace CPF is of vital importance for real-time evaluation of environmental and food safety. In this work, a novel organic photoelectrochemical transistor (OPECT) with TiO 2 /CdS heterojunction serving as the photogating module against the (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT:PSS) channel was developed for the high sensitive and selective detection of CPF. The TiO 2 /CdS heterojunction significantly improves the light absorption and charge separation efficiency of gate (G), and drives the directional migration of cations in the electrolyte to the channel under light conditions, reducing the channel carrier concentration. The C=N and P=S in CPF chelate with cadmium (Cd) ions, blocking the electron transfer between electron donor and gate, resulting in changes in effective gate voltage, which in turn leads to changes in channel current, and realizing highly sensitive and specific detection of CPF. The platform demonstrated a good linear response in the detection range of 100 ng/mL to 0.1 pg/mL, with detection limit as low as 2.2 fg/mL. This work provides an efficient and sensitive detection platform for the design of novel organic photochemical transistors for the detection of low concentration organophosphorus pesticides.