Ultra-low misorientation angle in small-molecule semiconductor/polyethylene oxide blends for organic thin film transistors

In this work, we report for the first time the use of a nonconjugated semicrystalline polymer as a film-forming agent to control the crystallization and tune the charge transport of solution-processed, small-molecule organic semiconductors. When 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS pentacene) was demonstrated as a representative material to blend with polyethylene oxide (PEO) polymer, it crystallized into uniformly-aligned needles with reduced random orientation, enhanced long-range order and elevated areal coverage. Specifically, an ultra-low misorientation angle of 7.9° ± 3.5° was obtained with 10% PEO additive, beneficial for charge transport in the TIPS pentacene/PEO hybrid film. Bottom-gate, top-contact organic thin film transistors (OTFTs) based on TIPS pentacene/PEO mixture were found to show a field-effect mobility up to 2.5 × 10⁻² cm²/Vs. This work may be universally applied to other organic semiconductors to regulate their crystal formation, enhance film forming and improve device performance of OTFTs. It contributes to the utilization of flexible substrates for future-generation high-performance organic electronics.