Controlled Nanoporous Structures of Ultrathin π-Conjugated Polymer Films for Highly Sensitive Gas Sensors

Abstract

Conventional OFET-based chemical sensors have severe limitations in terms of sensitivity owing to poor analyte diffusion and poor interaction between the analyte and charge carriers in the CP film. To overcome this drawback, it is imperative to fabricate CP films that can facilitate analyte diffusion and provide large adsorption sites for interactions between the analytes and charge carriers concentrated in the conducting channel of OFETs. This study is to develop a facile strategy to fabricate ultrathin nanoporous Conducting polymer(CP) films for high-performance OFET gas sensors based on shearing-assisted phase separation (SAPS) of polymer blends, followed by selective solvent etching. In this method, the morphological features of nanoporous CP films, such as pore size and film thickness, can be tuned in the nanoscale regime by simply varying the shear rate. This indicates that the nanoporous P3HT films were ultrathin. Owing to these morphological features, the resulting OFET sensors exhibited excellent sensing performance when exposed to NH3 gas. We demonstrated that our approach for modulating the morphological features of CP thin films is also applicable to other CP/insulating-polymer-blend systems, including P3HT/PMMA and DPP-DTT/PS. The proposed strategy is simple and universal and can be used to fabricate ultrathin nanoporous CP films, which in turn can enable the development of high-performance, low-cost, portable OFET sensors for various commercial applications.