Large-Dimensional Organic Semiconductor Crystals with Poly(butyl acrylate) Polymer for Solution-Processed Organic Thin Film Transistors

Despite solution processed organic semiconductors have attracted much research attention, the randomized crystallization and large prevalence of grain boundary remain as a challenge to realize high performance organic electronic applications. In this work, we report the incorporation of poly(butyl acrylate) polymer additive with organic semiconductors with the mediation of a solvent vapor annealing method in order to modify the nucleation and crystal growth process. As 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was experimented as a benchmark semiconductor, we demonstrated that the TIPS pentacene/poly(butyl acrylate) mixture exhibits rigidly aligned crystals, large grain width and improved areal coverage. In particular, thin film morphological characterization indicated a substantial reduction in misorientation angle by approximately two orders of magnitude as well as a 5-fold enlargement of grain width. A grain boundary model is proposed as a theoretic basis to understand the connection between grain width and hole mobility. Bottom-gate, top-contact thin film transistors based on TIPS pentacene/poly(butyl acrylate) blends demonstrated enhanced hole mobility of up to 0.11 cm2/Vs.