Induced crystallization of rubrene with diazapentacene as the template

The poor crystallinity of rubrene in conventional films is a well-known obstacle limiting practical applications of rubrene in thin film transistors. Here we report a study on using 6,13-diazapentacene (DAP) as a template to induce crystallization of rubrene in thin film transistors. This study demonstrates that DAP is a suitable template molecule with negligible contribution to the conduction channel and leads to polycrystalline thin films of rubrene with field effect mobility as high as 0.68 cm² V⁻¹ s⁻¹. This induced-crystallization strategy highly depends on a unique octadecylphosphonic acid (ODPA) bilayer-step surface, which is found to play important roles in controlling the growth of both DAP and rubrene.