Quality of charge-transport pathway of organic semiconductors (OSC) strongly affects the performances of organic field-effect transistors (OFET). To achieve higher charge mobility, solution-processed single-crystal (SPSC) techniques have been used to decrease crystal defects. Although most SPSC techniques can align crystalline lattices of OSCs in the in-plane direction, whether the crystalline lattices are well-aligned in the out-of-plane direction, and whether polymorphism exist in the crystal arrays remain unclear. In this study, a characterization protocol based on polarized optical microscope (POM), X-ray diffraction and electron diffraction, is established to identify the lattice structure, the in-plane and out-of-plane lattice alignment, and polymorphism in the crystal array of OSCs. Results showed that SPSC methods induced great in-plane lattice alignment for TIPS-PEN and perylene. However, careful controls on the growth time and temperature are required in order to unify the out-of-plane lattice orientation of TIPS-PEN and to control the polymorphism of perylene. Unifying the out-of-plane lattice orientation and polymorphism were found to improve the performances and reproducibility of the solution-processed OFETs.

Influences of polymorphism and low-angle grain boundary on OFET performances

254th National Meeting (2017)

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