Temperature-mediated morphological control of organic semiconductor crystals for organic field-effect transistors

Organic semiconductor crystals with well-defined morphologies are highly desirable for high-performance optoelectronic devices, yet precise control over their growth remains a challenge. Here, a novel donor-acceptor (D-A) molecule, TQDPT, has been successfully developed, featuring a rigid π-conjugated acceptor core composed of thiazoloquinoxaline and naphthalene, coupled with phenylphenothiazine donors. This study presents a temperature-mediated crystallization strategy for precisely controlling the morphology and carrier transport properties of TQDPT single crystals. By systematically investigating the growth kinetics across a controlled temperature range (15–35°C), we reveal a distinct transition from needle-like structures to plate-like crystals, with tunable average widths spanning from around 2.8 to 30.1 μm. This morphological evolution is driven by temperature-dependent molecular diffusion and nucleation kinetics. Significantly, the plate-like crystals grown at 25°C exhibit an order-of-magnitude enhancement in mobility compared to needle-like counterparts, while higher temperatures of 35°C yield broader crystals with improved carrier mobility and device stability. This work highlights the critical role of temperature as a pivotal parameter in the dimensional and electronic optimization of organic crystals, offering an attractive approach to optimize functional materials for advanced optoelectronics.