Self-alignment of 6,13-bis(triisopropylsilylethynyl)pentacene molecules through magnetic flux-affected nanoparticle motion in solution-processed transistors

We propose a viable method of inducing the self-alignment of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) molecules using magnetic nanoparticles under a controlled magnetic field. An essential feature of the self-alignment of TIPS-pentacene containing magnetic nanoparticles is systematically studied through meticulous understanding of gradient solvent evaporation in a magnetic nanoparticle-dispersed droplet guided by a static magnetic field. It is found that such TIPS-pentacene molecules are spontaneously aligned by magnetic flux-affected nanoparticle motion with the generation of gradual anisotropic solvent evaporation. In particular, by controlling the effective magnetic force applied to a magnetic nanoparticle-containing TIPS-pentacene solution, TIPS-pentacene droplet flow can be induced, causing greater alignment. We fabricate TIPS-pentacene-based transistors to confirm the effect of this aligned state on device performance, using both optical and electrical methods.