Phase segregation effect on TIPS pentacene crystallization and morphology for organic thin film transistors

In this study, we report that the vertical phase separation between a small-molecule organic semiconductor and a polymer additive can be utilized to drive semiconductor crystallization, enhance thin film morphology, and improve device performance of solution-processed organic thin film transistors (...

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Bibliographic Details
Published in:Journal of materials science. Materials in electronics 2020-03, Vol.31 (6), p.4503-4510
Main Authors: He, Zhengran, Bi, Sheng, Asare-Yeboah, Kyeiwaa, Zhang, Ziyang
Format: Article
Language:English
Subjects:
Acrylic resins
Characterization and Evaluation of Materials
Charge transport
Chemistry and Materials Science
Crystal structure
Crystallization
Hole mobility
Materials Science
Morphology
Optical and Electronic Materials
Organic semiconductors
Phase separation
Polymers
Semiconductor devices
Semiconductor materials
Thin film transistors
Thin films
Transistors
Ultrasonic testing
Vertical separation
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Summary:In this study, we report that the vertical phase separation between a small-molecule organic semiconductor and a polymer additive can be utilized to drive semiconductor crystallization, enhance thin film morphology, and improve device performance of solution-processed organic thin film transistors (OTFTs). When 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was demonstrated as a benchmark semiconductor material to blend with a polyacrylate polymer additive poly(2-ethylhexyl acrylate) (P2EHA), it was found that a vertical phase segregation occurred between TIPS pentacene and P2EHA, providing a confinement of anisotropic semiconductor crystallization and resulting in an elevated TIPS pentacene concentration at the charge transport interface. Accordingly, distinctive TIPS pentacene thin film morphology in terms of areal coverage, grain width, and crystal orientation was obtained by varying the loading ratio of the P2EHA polymer additive. Bottom-gate and bottom-contact OTFTs were fabricated to test charge transport and a hole mobility of up to 0.27 cm 2 /Vs was demonstrated with 80% loading ratio of P2EHA. The effective experimental method and important results as we showcased in this work can be applied to drive crystallization and optimize film morphology of small-molecule organic semiconductors other than TIPS pentacene.
ISSN:0957-4522
1573-482X
DOI:10.1007/s10854-020-02999-3