Incorporation and electronic sensing device effects of aniline functionality in diketopyrrolopyrrole–thiophene semiconducting polymers†

Abstract

The detection and monitoring of volatile organic compounds (VOCs) are crucial in environmental and medical monitoring. Organic field-effect transistor (OFET)-based sensors offer several advantages over conventional spectroscopic methods, including real-time, low-power, and wearable integration capabilities. In particular, diketopyrrolopyrrole (DPP)-based polymers exhibit exceptional semiconducting properties, making them promising candidates for active layers in OFET sensors. Their chemical tunability enables the incorporation of selective and sensitive biomarker moieties, either on the polymer backbone or side chains, to enhance analyte specificity. In this study, we synthesized a series of seven DPP-based copolymers functionalized with aniline derivatives named P1, P2, P3, P1BT1:1, P1BT1:2, P3BT1:1 and P3BT1:2 as biomarkers for acetone sensing. The aniline functionalities were systematically modified with electron-donating (methoxy) and electron-withdrawing (chloro) substituents to evaluate their impact on sensor performance. Device optimization was achieved by investigating different dielectric materials, including SiO₂ and cross-linked polystyrene on SiO₂, the latter effectively reducing observed gate leakage. Further optimization of the semiconducting layer was performed by comparing devices incorporating pristine aniline-functionalized DPP polymers with those utilizing a blend of pristine polymers and PDPP4T to enhance charge transport. The sensing performance of the optimized OFET devices was evaluated for acetone, dimethyl carbonate, and acetic acid, in vapor and solution phases. The findings from this study provide insights into the structure–property relationships of DPP-based semiconductors for VOC detection and highlight their potential for integration into portable electronic sensors.