Ultraviolet-Light-Induced Growth of 6,13-Bis(triisopropylsilylethynyl)pentacene Spherulites

Abstract

Spin-cast small π-conjugated molecules exhibit poor molecular order because of rapid evaporation of the solvent, resulting in low charge-carrier mobility. Herein, we present simple ultraviolet (UV) exposure methods as a versatile post-treatment for inducing the growth of crystalline spherulites of 6,13-bis-(triisopropylsilylethynyl)pentacene (TIPS-PEN). The UV exposure effectively transformed the amorphous state into a crystalline phase in the solid films. UV exposure of the TIPS-PEN films spincast using toluene with a high boiling point improved the intermolecular interaction within only a few minutes, which enhanced charge-carrier transport in organic transistors prepared using these films. The presence of residual solvent facilitated the mobilization of TIPS-PEN molecules, enabling their reorganization. Furthermore, UV exposure of the patterned specific regions in TIPS-PEN films reduced the off-state currents in the organic transistors prepared using the films.