Classification of Semiconducting Polymeric Mesophases to Optimize Device Post-Processing

Published

August 17, 2015

Author(s)

Chad R. Snyder, Regis J. Kline, Dean M. DeLongchamp, Ryan C. Nieuwendaal, Lee J. Richter, Martin Heeney, Iain McCulloch

Abstract

Semiconducting polymers form a variety of phases and mesophases that respond differently to post-deposition solvent or thermal treatments. Here it is shown that classification of these materials into their appropriate mesophases can be a useful tool to optimize their post-deposition treatments. Calorimetry is used to quantify differences between materials having similar molecular structures, using a well-established framework based on the kinetics and thermodynamics of phase changes. By way of example, this classification scheme is used to identify differences in three polymers, poly(3-hexylthiophene-2,5-diyl) and two isomeric bithiophene-thiophene copolymers. It is demonstrated that poly(3-hexylthiophene) is a “normal” polymer crystal, and that the two bithiophene copolymers have liquid crystalline phases. The diverse phase structure is notable in light of the molecular similarity of the three polymers, and it has an impact on optimum post-processing conditions for maximum field effect charge carrier mobility in thin film transistor devices. Strong superheating effects are demonstrated for the two bithiophene-thiophene copolymers and the impact on annealing is demonstrated using grazing incidence X-ray diffraction.

Citation

Journal of Polymer Science Part B-Polymer Physics

Volume

53

Pub Type

Journals

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DOI Link

Keywords

flexible electronics, organic thin film transistors, photovoltaics, mesophases, liquid crystals, polymers

Citation

Snyder, C. , Kline, R. , DeLongchamp, D. , Nieuwendaal, R. , Richter, L. , Heeney, M. and McCulloch, I. (2015), Classification of Semiconducting Polymeric Mesophases to Optimize Device Post-Processing, Journal of Polymer Science Part B-Polymer Physics, [online], https://doi.org/10.1002/polb.23801 (Accessed April 23, 2024)