Organic thin-film transistor properties and the structural relationships between various aromatic end-capped triisopropylsilylethynyl anthracene derivatives

We describe the preparation and characterization of single crystals and thin films composed of three new small molecules based on soluble triisopropylsilylethynyl (TIPS)-substituted anthracene (TIPSAnt) for use in organic thin-film transistors (TFTs); the three molecules examined were TIPSAnt derivatives containing thiophene (TIPSAntT), benzothiophene (TIPSAntBeT), or phenyl thiophene (TIPSAntPT) end cappers. We elucidated the relationship between the molecular structures and TFT performances by measuring the thermal, optical, electrochemical, crystalline, and morphological properties of these molecules. TIPSAntPT was able to achieve a “bricklayer” type of molecular stacking structure, facilitated by the bulky phenyl thiophene substituents. This is the first report of a “bricklayer” stacking structure of triisopropylsilylethynyl anthracene derivatives. Among the three molecules, TIPSAntPT showed the highest TFT mobility, 0.063 cm2/Vs for the film state and 0.12 cm2/Vs for single crystals. By contrast, in the case of in TIPSAntBeT, the introduction of the rigid substituent group led to poor TFT device performance. TFT device performances could be explained in terms of thin-film morphology, investigated by atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis.