Strain-induced carrier mobility modulation in organic semiconductors

We systematically investigated the strain-induced carrier mobility of two representative n-type and p-type organic semiconductors, 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) and N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8), in order to understand the relationship between the carrier mobility and intermolecular packing configurations. The applied strain to organic semiconductors changes the intermolecular packing configurations, such as the π–π stacking distance and π–π overlap extent between adjacent π-conjugated molecules. In particular, the in-phase and out-of-phase π–π orbital interactions cause carrier mobility variations and energy level splitting by constructive/bonding and destructive/antibonding interactions between adjacent π-conjugated molecules. Our results demonstrate periodic changes of the strain-induced carrier mobility with respect to the π–π stacking distance and π–π overlap type, respectively. Furthermore, we propose that the periodic behaviors of carrier mobility can be attributed to the alternating phase changes of the molecular orbital interactions under applied strain. Based on the understanding of the intermolecular interactions and the structure–property relationships, we can provide a strain path for optimal carrier mobility modulation and the development of high-performance organic electronic devices.