Solution Processable Pentafluorophenyl End‐Capped Dithienothiophene Organic Semiconductors for Hole‐Transporting Organic Field Effect Transistors

Abstract

AbstractTwo solution‐processable organic semiconductors, DFPT‐DTTR (1) and DFPbT‐DTTR (2), composed of pentafluorophenyl (FP) end‐capped 3,5‐dialkyl dithienothiophene (DTTR) core with thiophene (T) or bithiophene (bT) as π‐bridged spacers are developed and investigated for their optical, electrochemical, microstructural, and electrical properties. With more conjugated bithiophene units, compound 2 exhibits a red‐shifted UV–vis absorption band and upshifted HOMO/downshifted LUMO energy levels. According to the density functional theory, compound 2 features a more twisted molecular structure due to the intrinsic non‐coplanar blocks in the π‐backbones. Compound 1‐based organic field effect transistors exhibit efficient hole transport with mobility up to 0.48 cm2 V−1 s−1. This is one of the high mobility organic semiconductors exhibiting p‐channel characteristics based on solution‐processable small molecular FP end‐capped fused/oligothiophenes. With large and interconnected crystalline morphologies, decreased π–π stacking distance, and less steric hindrance, compound 1 exhibits two orders of magnitude higher mobility than the more distorted 2, which exhibits lower hole mobility of 1.82 × 10−3 cm2 V−1 s−1.