Uniform electroactive fibre-like micelle nanowires for organic electronics

Xiaoyu Li,Jieshu Qian,Ian Manners,Piotr J Wolanin,Mitchell A Winnik,Liam R Macfarlane,Charl F J Faul,John Rudin,Martin J Cryan,Thomas Schmaltz,Thomas G Dane,Robert L Harniman,Holger Frauenrath,Oliver E C Gould

doi:10.1038/ncomms15909

Abstract

Micelles formed by the self-assembly of block copolymers in selective solvents have attracted widespread attention and have uses in a wide variety of fields, whereas applications based on their electronic properties are virtually unexplored. Herein we describe studies of solution-processable, low-dispersity, electroactive fibre-like micelles of controlled length from π-conjugated diblock copolymers containing a crystalline regioregular poly(3-hexylthiophene) core and a solubilizing, amorphous regiosymmetric poly(3-hexylthiophene) or polystyrene corona. Tunnelling atomic force microscopy measurements demonstrate that the individual fibres exhibit appreciable conductivity. The fibres were subsequently incorporated as the active layer in field-effect transistors. The resulting charge carrier mobility strongly depends on both the degree of polymerization of the core-forming block and the fibre length, and is independent of corona composition. The use of uniform, colloidally stable electroactive fibre-like micelles based on common π-conjugated block copolymers highlights their significant potential to provide fundamental insight into charge carrier processes in devices, and to enable future electronic applications.

Highlights

Micelles formed by the self-assembly of block copolymers in selective solvents have attracted widespread attention and have uses in a wide variety of fields, whereas applications based on their electronic properties are virtually unexplored
The block copolymers (BCPs) used to prepare the fibre-like micelles used in this study possessed a crystallizable core-forming regioregular poly(3-hexylthiophene) block[6,7,8,9,10] and a solubilizing, amorphous coronal block
To allow us to probe the influence of the corona on charge transport, two different coronas were investigated: regiosymmetric poly(3-hexylthiophene)[21,32,33,34] and polystyrene (PS)

Summary

Introduction

Micelles formed by the self-assembly of block copolymers in selective solvents have attracted widespread attention and have uses in a wide variety of fields, whereas applications based on their electronic properties are virtually unexplored. The use of uniform, colloidally stable electroactive fibre-like micelles based on common p-conjugated block copolymers highlights their significant potential to provide fundamental insight into charge carrier processes in devices, and to enable future electronic applications. Fibres fabricated from solely p-conjugated homopolymers have been studied in particular detail and high charge carrier mobilities (m) have been reported[27,28,29] These one-dimensional nanostructures exhibit limited colloidal stability and access to uniform samples of controlled length that allows optimization for different applications remains a severe challenge[30,31]. We report the exploration of the potential of colloidally stable fibre-like BCP micelles with precisely controllable length, low dispersities and a p-conjugated core both to provide insight into the factors that influence device performance and to enable wider organic electronic applications

Methods

Results

Conclusion