Development of High-Sensitivity Poly(2,7-(9,9-dioctylfluorene)-alt-5,5-(4′,7′-di-2-thienylbenzo [c][1,2,5]thiadiazole)) Thin-Film-Based Phototransistors by the Ribbon-Floating Film Transfer Method

Abstract

Alignment of polymer chains holds the key to the development of highly functional polymer-based field-effect transistors (FETs). The recently developed ribbon-floating film transfer method (ribbon-FTM) has the potential for development of polymer thin films with highly aligned chains, which are desirable for fabrication of efficient planar devices. These thin films consisting of well-aligned polymer chains exhibit high degree of optical and electronic anisotropies. Herein, ribbon-FTM-processed thin-film-based organic photosensitive transistors of poly(2,7-(9,9-dioctylfluorene)-alt-5,5-(4′,7′-di-2-thienylbenzo [c][1,2,5]thiadiazole)) (PFO-DBT) are reported. Under optimized fabrication conditions, polymer FETs based on PFO-DBT demonstrate a charge carrier mobility of 0.002 cm2 V−1 s−1 and an on–off ratio of 5 × 104 under dark conditions. The devices further demonstrate a photosensitivity of ≈104 and 103 and a high responsivity of 8.37 and 4.6 A W−1 against green and red light illuminations, respectively. The results hold promise for the development of conducting-polymer-based high-performance photosensitive organic field-effect transistors (OFETs). © 2021 Wiley-VCH GmbH