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One-Step Macroscopic Alignment of Conjugated Polymer Systems by Epitaxial Crystallization during Spin-Coating

Christian Müller (Institutionen för kemi- och bioteknik, Polymerteknologi) ; M. Aghamohammadi ; S. Himmelberger ; P. Sonar ; M. Garriga ; A. Salleo ; M. Campoy-Quiles
Advanced Functional Materials (1616-301X). Vol. 23 (2013), 19, p. 2368-2377.
[Artikel, refereegranskad vetenskaplig]

The one-step preparation of highly anisotropic polymer semiconductor thin films directly from solution is demonstrated. The conjugated polymer poly(3-hexylthiophene) (P3HT) as well as P3HT:fullerene bulk–heterojunction blends can be spin-coated from a mixture of the crystallizable solvent 1,3,5-trichlorobenzene (TCB) and a second carrier solvent such as chlorobenzene. Solidification is initiated by growth of macroscopic TCB spherulites followed by epitaxial crystallization of P3HT on TCB crystals. Subsequent sublimation of TCB leaves behind a replica of the original TCB spherulites. Thus, highly ordered thin films are obtained, which feature square-centimeter-sized domains that are composed of one spherulite-like structure each. A combination of optical microscopy and polarized photoluminescence spectroscopy reveals radial alignment of the polymer backbone in case of P3HT, whereas P3HT:fullerene blends display a tangential orientation with respect to the center of spherulite-like structures. Moreover, grazing-incidence wide-angle X-ray scattering reveals an increased relative degree of crystallinity and predominantly flat-on conformation of P3HT crystallites in the blend. The use of other processing methods such as dip-coating is also feasible and offers uniaxial orientation of the macromolecule. Finally, the applicability of this method to a variety of other semi-crystalline conjugated polymer systems is established. Those include other poly(3-alkylthiophene)s, two polyfluorenes, the low band-gap polymer PCPDTBT, a diketopyrrolopyrrole (DPP) small molecule as well as a number of polymer:fullerene and polymer:polymer blends.

Nyckelord: polymer semiconductors, fullerene, bulk–heterojunction, nucleation, epitaxy, spherulite



Denna post skapades 2013-05-21. Senast ändrad 2015-03-02.
CPL Pubid: 177189

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Polymerteknologi (2005-2014)

Ämnesområden

Polymerteknologi

Chalmers infrastruktur