Anisotropic Structure and Charge Transport in Highly Strain‐Aligned Regioregular Poly(3‐hexylthiophene)

Abstract

A novel method of strain‐aligning polymer films is introduced and applied to regioregular poly(3‐hexylthiophene) (P3HT), showing several important features of charge transport. The polymer backbone is shown to align in the direction of applied strain resulting in a large charge‐mobility anisotropy, where the in‐plane mobility increases in the applied strain direction and decreases in the perpendicular direction. In the aligned film, the hole mobility is successfully represented by a two‐dimensional tensor, suggesting that charge transport parallel to the polymer backbone within a P3HT crystal is strongly favored over the other crystallographic directions. Hole mobility parallel to the backbone is shown to be high for a mixture of plane‐on and edge‐on packing configurations, as the strain alignment is found to induce a significant face‐on orientation of the originally highly edge‐on oriented crystalline regions of the film. This alignment approach can achieve an optical dichroic ratio of 4.8 and a charge‐mobility anisotropy of 9, providing a simple and effective method to investigate charge‐transport mechanisms in polymer semiconductors.

Molecular origin of high field-effect mobility in an indacenodithiophene–benzothiadiazole copolymer

“…This can be demonstrated by the absence of overlap between the blue traces (/y p S GIXD ) and the highlighted areas (/y p S NEXAFS ) in Fig. 8b,c, where fast-dried, non-annealed films of P3HT 24 and DPPT-T, a DPP-terthiophene copolymer 25 , are analysed. This quantitative comparison of NEXAFS and GIXD results can therefore be applied as a method to reveal backbone rigidity in a variety of semiconducting polymers.…”

“…17) moieties. Moreover, accumulating evidence that challenges the superiority of the 2D in-plane packing motif has emerged when two films with same or similar chemical structures but disparate molecular packing behaviour are compared 16,[24][25][26] . These intriguing findings signify a lack of comprehension of what is essential to achieving high mobility besides long-range order.…”

Ultrahigh electrical conductivity in solution-sheared polymeric transparent films

“…Polarized UV-visible (UV-vis) spectroscopy was used to extensively characterize the transparency and electronic transitions, the latter of which can be correlated to molecular ordering and aggregation in thin polymer films (33). Unpolarized absorption in sheared films reveals a weak, broad feature occurring near 800 nm, a feature not present in spin-cast films (Fig.…”

Casting Control of Floating-films into Ribbon-shape Structure by modified Dynamic FTM

“…One of the amicable solutions for this problem is the introduction of macromolecular alignment of CPs. Various methods to prepare oriented thin-films such as friction transfer method [2], mechanical rubbing [3], solution flow [4], capillary action [5], solution shearing [6], slide coating [7] and strain alignment [8] importance for fabricating organic electronic devices by using oriented thin films of CPs in the last one decade, important challenges like simplicity of fabrication process and preparation of multilayer oriented films are yet to be taken into consideration. We have developed a dynamic casting of thin floating-film of CPs on liquid-substrate followed by its transfer on a desired substrate which has been named as dynamic-FTM.…”