Issue 17, 2015

Compatibility of amorphous triarylamine copolymers with solution-processed hole injecting metal oxide bottom contacts

Abstract

Triarylamine copolymers are p-type organic semiconducting materials which have been shown to have the crucial advantages of being air-stable, forming amorphous films (critical for device uniformity over large areas) and allowing the creation of high mobility transistors and highly efficient perovskite solar cells. A key area of recent technological progress has been the development of solution-processable metal oxides as charge injection layers in organic semiconducting devices. Here we report on the synthesis of a large ionization potential (IP = 5.65 eV) silafluorene bridged triarylamine copolymer poly(silafluorene-triarylamine) (PSiF-TAA), and compare its time-of-flight (TOF) bulk hole mobility to that of a fluorene bridged triarylamine copolymer poly(fluorene-triarylamine) (PF-TAA), (IP = 5.4 eV) and the homopolymer polytriarylamine (PTAA) (IP = 5.2 eV). Using these mobility values and current–voltage measurements, we then quantify the charge injection efficiency (χ) into these polymers from three ambiently-prepared solution processed hole-injecting contacts MoO3 (aqueous nanoparticle dispersion), V2O5 (sol–gel) and chlorinated indium tin oxide (Cl-ITO) (UV – solvent assisted), and compare them to the more conventional contacts ITO and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Whilst hole injection into PTAA is relatively unaffected by the nature of the contact, injection into PF-TAA and PSiF-TAA is greatly improved by the use of MoO3 and Cl-ITO. Despite its similar mobility and larger ionization potential compared to the homopolymer, the highest injection efficiency is achieved for PF-TAA, indicating the role of chemical design in optimizing charge injection into organic semiconductor devices.

Graphical abstract: Compatibility of amorphous triarylamine copolymers with solution-processed hole injecting metal oxide bottom contacts

Supplementary files

Article information

Article type
Paper
Submitted
13 nov 2014
Accepted
26 mar 2015
First published
31 mar 2015

J. Mater. Chem. C, 2015,3, 4530-4536

Author version available

Compatibility of amorphous triarylamine copolymers with solution-processed hole injecting metal oxide bottom contacts

S. Logan, J. E. Donaghey, W. Zhang, I. McCulloch and A. J. Campbell, J. Mater. Chem. C, 2015, 3, 4530 DOI: 10.1039/C4TC02593H

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