Organic photoelectrochemical transistor (OPECT) biosensing represents a new platform interfacing optoelectronics and biological systems with essential amplification, which, nevertheless, are concentrated on depletion-type operation to date. Here, a polymer dot (Pdot)-gated accumulation-type OPECT biosensor is devised and applied for sensitive urea detection. In such a device, the as-designed Pdot/poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is validated as a superior gating module against the diethylenetriamine (DETA) de-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) channel, and the urea-dependent status of Pdots has been shown to be sensitively correlated with the device's response. High-performance urea detection is thus realized with a wide linear range of 1 μM-50 mM and a low detection limit of 195 nM. Given the diversity of the Pdot family and its immense interactions with other species, this work represents a generic platform for developing advanced accumulation-type OPECT and beyond.
Keywords: accumulation-type; biosensor; organic transistor; photoelectrochemical; polymer dots.