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In−situ monitoring Poly(3-hexylthiophene) nanowire formation and shape evolution in solution via small angle neutron scattering

DOI: 10.1016/j.solmat.2019.110128 DOI Help

Authors: Francesco Bastianini (The University of Sheffield) , Gabriel E. Pérez (The University of Sheffield) , Adam R. Hobson (The University of Sheffield) , Sarah E. Rogers (ISIS Neutron and Muon Source) , Andrew J. Parnell (The University of Sheffield) , Martin Grell (The University of Sheffield) , Alfredo Flores Gutiérrez (The University of Sheffield) , Alan D. F. Dunbar (The University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Solar Energy Materials And Solar Cells , VOL 202

State: Published (Approved)
Published: November 2019
Diamond Proposal Number(s): 8117

Abstract: The crystallization of poly(3-hexylthiophene) (P3HT) to form nanowires has attracted considerable interest because this process significantly increases the hole mobility when compared to amorphous P3HT, leading to improved performance in photovoltaic and other organic electronic devices. However, full characterization of the crystallization self-assembly of the polymer chains in solution has not been achieved yet, due to limited use of in−situ not destructive techniques. Here, we investigate the ageing-driven formation and evolution of regioregular (rr) P3HT nanostructures in chlorobenzene solution using small angle neutron scattering (SANS) and UV–Vis spectroscopy. We have monitored how the shape of the rr-P3HT aggregates evolves. The initial states for rr-P3HT chains are the random coils, which straighten to form rods. These subsequently π - π stack to form 2D lamellae, which further stack to create nanowires. The formation of nanowires is promoted both by the length of ageing and by low temperatures ( 4∘C ). Temperatures above >40∘C reverse the formation of nanowires. Additionally, atomic force microscopy (AFM) and grazing incidence wide angle x-ray scattering (GIWAXS) reveal that the nanowires can be successfully aligned during deposition by off-axis spin coating. Finally, the anisotropic conductivity of the aligned rr-P3HT nanowire films is reported. This is significant for applications such as gas sensing or organic thin film transistors, where increased conductivity and controlled nanostructure are desirable.

Journal Keywords: P3HT; Conjugated polymer; Nanowires; Small angle neutron scattering SANS; Solution ageing; Alignment

Subject Areas: Materials, Chemistry, Energy


Instruments: I07-Surface & interface diffraction