Document Type

Article

Publication Date

9-13-2017

Department

Polymers and High Performance Materials

Abstract

The solid-state packing and polymer orientation relative to the substrate are key properties to control in order to achieve high charge carrier mobilities in organic field effect transistors (OFET). Intuitively, shorter side chains are expected to yield higher charge carrier mobilities because of a denser solid state packing motif and a higher ratio of charge transport moieties. However our findings suggest that the polymer chain orientation plays a crucial role in high-performing diketopyrrolopyrrole-based polymers. By synthesizing a series of DPP-based polymers with different branched alkyl side chain lengths, it is shown that the polymer orientation depends on the branched alkyl chain lengths and that the highest carrier mobilities are obtained only if the polymer adopts a mixed face-on/edge-on orientation, which allows the formation of 3D carrier channels in an otherwise edge-on-oriented polymer chain network. Time-of-flight measurements performed on the various polymer films support this hypothesis by showing higher out-of-plane carrier mobilities for the partially face-on-oriented polymers. Additionally, a favorable morphology is mimicked by blending a face-on polymer into an exclusively edge-on oriented polymer, resulting in higher charge carrier mobilities and opening up a new avenue for the fabrication of high performing OFET devices.

Comments

This is the peer reviewed version of the following article: , which has been published in final form at https://doi.org/10.1002/adfm.201701973. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Publication Title

Advanced Functional Materials

Volume

27

Issue

34

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