ИСТИНА

цель проекта заключалась в определении механизмов взаимодействия полярных и неполярных газов, включая низкомолекулярные газы и летучие органические соединения, с полупроводниковыми монослоями сопряженных олиготиофенов, а также в выявлении фундаментальной взаимосвязи между методом изготовления полупроводникового монослоя, его электрофизическими свойствами, а также методом регистрации сенсорного отклика с сенсорными свойствами и селективностью отклика на тот или иной газ.

The project aims to determine the mechanisms of interaction of polar and non-polar gases, including low molecular weight gases and volatile organic compounds, with semiconducting monolayers of conjugated oligothiophenes, as well as to establish a fundamental relationship between the method of manufacturing a semiconducting monolayer, its electrical properties, as well as the method of sensory response registration with sensory properties and selectivity of response to a particular gas. The relevance of the project is due to the high potential of organic thin-film field-effect transistors (OTFETs) using as sensors for polar low-molecular gases, as well as chemically inert volatile organic compounds due to the ultra-high sensitivity of their electrical characteristics to the environment composition, simple and potentially inexpensive production methods, multiparametric response to external stimulus, which allows to simultaneously analyze the change in several characteristics of one sensor on the effect of the gas being determined. As a result of the project, a representative range of organic thin-film field-effect transistors with a self-organizing semiconducting layer based on 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT-C8) and a siloxane benzothienobenzothiophene dimer with a hexyl terminal group and with an undecyl aliphatic spacer (O(Si-Und-BTBT-Hex)2), as well as an interface dielectric layer based on octyldimethylchlorosilane (ODMS), polymethyl methacrylate (PMMA), polystyrene (PS), and perfluorinated polymer (CYTOP). It was found that the optimal electrical characteristics of OTFTs are not a necessary and sufficient condition for the appearance of high sensory sensitivity of such devices, so the sensory and electrical properties should be optimized independently of each other, and further search for key factors affecting sensory properties is required. A multiparametric analysis of the nature of the shift in the transfer curves of the OTFTs in the presence of nitrogen dioxide made it possible to establish the optimal parameters of the OTFT corresponding to its response as a sensor, as well as the optimal algorithms for removing the sensory response. It is shown that with the transfer method of measuring sensory properties in the linear mode, the sensitivity is mainly determined by the change in the threshold voltage and the transition to the saturated regime increases the sensitivity to the maximum current and hole mobility, reducing the sensitivity to the threshold voltage almost to zero. In general, pulse measurements in linear mode provide the highest sensory sensitivity of OTFTs. A high correlation of sensory sensitivity with the electrical parameters of the OTFT, namely, the pre-threshold slope and the density of charge traps associated with it, is shown. The sensory response of an OTFT to volatile compounds with similar chemical structures and different dipole moments has been studied. It has been established that the dipole model of sensitivity is not applicable to the investigated OTFT devices and gases, while the proximity of the HOMO levels of the gas and semiconductor indicates a higher sensor sensitivity of the OTFT to this gas. One of the possible mechanisms is that the proximity of HOMO levels increases the probability of charge transfer from sorbed gas molecules to semiconducting molecules with its subsequent doping, which can be registered as a change in the macroscopic properties of thin films, for example, conductivity.