Issue 47, 2014

Charge mobility anisotropy of functionalized pentacenes in organic field effect transistors fabricated by solution processing

Abstract

To understand and optimize the performance of thin-film electronic devices incorporating crystalline organic semiconductors, it is important to consider the impact of their structural anisotropy on the charge transport. Here we report on the charge mobility anisotropy in 6,13-bis(triisopropylsilylethynyl) (TIPS) and 6,13-bis(triethylsilylethynyl) (TES) pentacene field effect transistors, in which microstructure is controlled by solution processing conditions. Thin-film structures that range from millimetre size, crystalline domains to macroscopic, high-aspect-ratio (∼1 μm wide and >1 cm long) needles are systematically produced by controlling the substrate displacement rate during zone-cast deposition. Through precise control of the microstructure we experimentally explore the differences in charge transport anisotropy between TIPS- and TES-pentacene molecules. Aligned needles of TIPS- pentacene result in a mobility anisotropy (μ/μ) of ∼20 (mobility of ∼0.7 cm2 V−1 s−1) whereas TES-pentacene produce an order of magnitude lower mobility (∼0.06 cm2 V−1 s−1) but much higher mobility anisotropy (>45). Such significant changes in absolute mobility and mobility anisotropy are attributed to their different packing structures, which permit 2D charge transport in TIPS-pentacene and 1D transport in TES-pentacene. Bulky TIPS- side groups (diameter ∼7.5 Å) force a brick-wall type packing structure, whereas TES- side groups (diameter ∼6.6 Å) pack in a 1D slipped-stack. Furthermore, through precise control of the molecular alignment, the impact of crystal orientation on charge transport is investigated. TIPS-pentacene achieves the highest mobility when the angle between the needle long-axis and charge transport directions is ∼35°, whereas in TES-pentacene it is much closer to 0°. These results are supported by theoretical simulations.

Graphical abstract: Charge mobility anisotropy of functionalized pentacenes in organic field effect transistors fabricated by solution processing

Supplementary files

Article information

Article type
Paper
Submitted
24 Jūn. 2014
Accepted
26 Sept. 2014
First published
20 Okt. 2014

J. Mater. Chem. C, 2014,2, 10110-10115

Charge mobility anisotropy of functionalized pentacenes in organic field effect transistors fabricated by solution processing

J. Wade, F. Steiner, D. Niedzialek, D. T. James, Y. Jung, D. Yun, D. D. C. Bradley, J. Nelson and J. Kim, J. Mater. Chem. C, 2014, 2, 10110 DOI: 10.1039/C4TC01353K

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements