Single Crystal X-ray, AFM, NEXAFS, and OFET Studies on Angular Polycyclic Aromatic Silyl-Capped 7,14-Bis(ethynyl)dibenzo[b,def]chrysenes

The impact of molecular packing and alignment of 7,14-bis((triethylsilyl)ethynyl)dibenzo[ b,def ]chrysene (TES-DBC) and 7,14-bis((triisopropylsilyl)ethynyl)dibenzo[ b,def ]chrysene (TIPS-DBC) on OFET performance was investigated. The bulk solid state packing of these angular polycyclic aromatic hydrocarbons (PAHs) was analyzed via single crystal X-ray analysis, and their molecular stacking arrangements on HMDS modified SiO 2 substrate were studied using near edge X-ray absorption fine structure spectroscopy (NEXAFS) at the carbon K-edge. Our studies found that TES- and TIPS-DBC have significantly different solid state packing arrangements and tilt angles, yet have OFET mobilities that are comparable at 1.6 × 10 –3 and 1.0 × 10 –3 cm 2 /Vs, respectively. The deposition method also has a dramatic impact on film morphology.