Solution processable TIPS-benzodithiophene small molecules with improved semiconducting properties in organic field effect transistors

Four soluble triisopropylsilylethynyl benzodithiophene (TIPS-BDT) derivatives containing allylphenylene (TIPS-BDT-VP), allyloxyphenylene (TIPS-BDT-AOP), fluorophenylene (TIPS-BDT-FP) and thiophene (TIPS-BDT-T) aromatics as end cappers were synthesized by Suzuki or Stille coupling. A comparable study of the relationship between the molecular structure and the device performance is done by measurements of the electrochemical, thermal and optical properties of these materials. These small molecules exhibit an increased solubility and could be employed as the active component by spin-coating from solution in organic field effect transistors on flexible PET-foils. All small molecules showed good film-forming properties and high field effect transistor performance. A hole mobility of up to 0.09 cm2/Vs with high on/off current ratio of 106 was determined for TIPS-BDT-FP. This mobility is only one order of magnitude lower in comparison to the today best solution processable material (e.g. TIPS-Pentacene). For the syntheses of novel semiconducting materials, both small molecules and polymers, a TIPS-BDT core is a potential precursor.

Graphical abstractNovel benzodithiophene-based small molecules provide hole transport materials with good film-forming properties on flexible substrates and promising performance as the active layer in organic field effect transistors.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of four TIPS-benzodithiophene based small molecules. ► Characterization of the novel materials with CV,UV/Vis and DSC. ► Study of the relationship between the molecular structure and the device performance. ► All materials show characteristical hole transporting properties as active organic layers in OFETs. ► Improved OFET-performance with fluorine atoms attached on the small molecule with mobilities up to 0.09 cm2/Vs and on/off 106.