Taming Charge Transport in Semiconducting Polymers with Branched Alkyl Side Chains
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 24, 2017
- Source ID
- 10.1002/adfm.201701973
Entities
People
- Bob C Schroeder
- Ging‐ji Nathan Wang
- Jaewan Mun
- James W. E. Kneller
- Leo Shaw
- Michael F. Toney
- Tadanori Kurosawa
- Theo Kreouzis
- Tianren Fu
- Xiaodan Gu
- Yu‐cheng Chiu
- Zhenan Bao
Organizations
- Croucher Foundation
- Office of Naval Research
- Queen Mary University of London
- SLAC National Accelerator Laboratory
- Stanford University
- United States Department of Energy
- University of Southern Mississippi
- University of Tokyo
- Yuan Ze University