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Two 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. [ABSTRACT FROM AUTHOR]

Three new solution‐processable organic semiconductors (1–3) are synthesized and characterized for p‐type organic field effect transistors (OFETs). The backbone of these small molecules is modified by expanding the central core conjugation from thienothiophene (TT) to dithienothiophene (DTT) and tetrathienoacene (TTA), which are end‐capped with soluble β‐substituted alkyl chains dithienothiophenes (DTTR) to generate DTTR‐TT (1), DTTR‐DTT (2), and DTTR‐TTA (3). The highest mobility of 0.016 cm2 V−1 s−1 is achieved using solution‐sheared DTTR‐TTA film due to the extended conjugated TTA core, which enhances the intermolecular interaction and generates an efficient percolation for the OFET channel. Solution blending of crystalline DTTR‐TT small molecules with oriented‐packing polymer dithienothiophene‐thioalkylbithiophene (PDTT‐SBT) polymer leads to significantly enhanced mobilities from 0.0009 up to 0.22 cm2 V−1 s−1, occurring at an optimized 30% DTTR‐TT composition in the blend. Hole mobility of 30% DTTR‐TT blend is 0.22 cm2 V−1 s−1 which is higher than pristine small molecule DTTR‐TT (0.0009 cm2 V−1 s−1) and polymer PDTT‐SBT (0.067 cm2 V−1 s−1), respectively. An efficient strategy to enhance the mobility of small molecule DTTR‐TT by blending with easily synthesizable PDTT‐SBT polymer is reported. [ABSTRACT FROM AUTHOR]

Three new organic semiconductors with alkyl chain-substituted tetrathienoacene (TTAR) as the central core and both ends capped with thiophene (DT-TTAR), thienothiophene (DTT-TTAR) and dithienothiophene (DDTT-TTAR) have been synthesized and characterized for organic field effect transistor (OFET) applications. A hole mobility of 0.81 cm2 V−1 s−1 was achieved for the DDTT-TTAR film, which represents the highest mobility yet found for a solution-processable p-type TTAR-based small molecular semiconductors. [ABSTRACT FROM AUTHOR]