Poly(butyl acrylate) polymer enhanced phase segregation and morphology of organic semiconductor for solution-processed thin film transistors

The phase segregation as a result of mixing organic semiconductors with polymeric additives has been reported as an intriguing avenue to optimize semiconductor crystal microstructure, active layer composition and charge carrier transport. In this work, we report the mixing of organic semiconductor 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) with poly(butylacrylate) as a polymer additive to control the semiconductor crystal growth and morphology. The incorporation of poly(butylacrylate) induces a vertical phase segregation but a more predominant lateral phase segregation with TIPS pentacene. Along with a solvent vapor annealing technique, poly(butylacrylate) evenly distributes the semiconductor nuclei on the polymer matrix, and results in organic crystal with enlarged grain width. In addition, the randomized crystal growth of TIPS pentacene has been significantly reduced, giving rise to a 25-fold decrease in misorientation angle. The bottom-gate, top-contact thin film transistors with the poly(butylacrylate)/TIPS pentacene mixture as the active layer demonstrated an improved hole mobility of 0.11 cm²/Vs. We believe the phase segregation induced by the poly(butylacrylate) polymer as well as the solvent vapor annealing method as reported in this work can be facilely replicated on other organic semiconductors to realize high performance organic electronic device applications.