Surface Doping of Mercury-Sensing Molecules in the Semiconducting Channel of Organic Field-Effect Transistors

This article explores the growth mechanism of a pyridine-end oligo-p-phenylenevinylene derivative, a mercury-sensing molecule deposited via thermal vacuum deposition on pentacene dendrite structures in a top-contact-bottom-gate organic field-effect transistor (OFET) configuration, facilitating a methodology to develop sensors for point-of-care. The sensing molecule features a lone pair at the nitrogen atom in the pyridine end, enabling the formation of a selective coordination complex with mercury ions. OFETs rely on semiconducting and dielectric layers, which are crucial for analyte sensing. Introducing a thin layer of receptor molecules, specifically binding with mercury, atop the organic semiconductor allows its use as a sensing layer without compromising its active layer functionality. Surface doping of receptor molecules above organic semiconductors alters the electronic properties through grain boundary permeation. The controlled, uniform growth of mercury-sensing molecules above semiconductors promises highly effective sensing devices. Surface analysis reveals diffusion through grain boundaries, emphasizing the need for meticulous fabrication attention. The deposition of thin films over organic semiconductors may impede charge transport, warranting a comprehensive examination of the growth mechanisms that optimize device performance. Surface roughening and smoothening processes significantly influence surface morphology, which is crucial for effective sensing applications, as they modulate surface characteristics impacting sensing-device performance.