Charge-carrier density independent mobility in amorphous fluorene-triarylamine copolymers
Author(s)
Type
Journal Article
Abstract
A charge-carrier density dependent mobility has been predicted for amorphous, glassy
energetically-disordered semiconducting polymers, which would have considerable impact on
their performance in devices. However, previous observations of a density dependent mobility
are complicated by the polycrystalline materials studied. Here we investigate charge transport in
field-effect transistors and diodes of two amorphous, glassy fluorene-triarylamine copolymers,
and explore the results in terms of a charge-carrier density dependent mobility model. The nondispersive
nature of the time-of-flight (TOF) transients and analysis of dark injection transient
results and transistor transfer characteristics indicate a charge-carrier density independent
mobility in both the low-density diode and the high-density transistor regimes. The mobility
values for optimised transistors are in good agreement with the TOF values at the same field, and
both have the same temperature dependency. The measured transistor mobility falls two to three
orders of magnitude below that predicted from the charge-carrier density dependent model, and
does not follow the expected power-law relationship. The experimental results for these two
amorphous polymers are therefore consistent with a charge-carrier density independent mobility,
and we discuss this in terms of polaron-dominated hopping and interchain correlated disorder.
energetically-disordered semiconducting polymers, which would have considerable impact on
their performance in devices. However, previous observations of a density dependent mobility
are complicated by the polycrystalline materials studied. Here we investigate charge transport in
field-effect transistors and diodes of two amorphous, glassy fluorene-triarylamine copolymers,
and explore the results in terms of a charge-carrier density dependent mobility model. The nondispersive
nature of the time-of-flight (TOF) transients and analysis of dark injection transient
results and transistor transfer characteristics indicate a charge-carrier density independent
mobility in both the low-density diode and the high-density transistor regimes. The mobility
values for optimised transistors are in good agreement with the TOF values at the same field, and
both have the same temperature dependency. The measured transistor mobility falls two to three
orders of magnitude below that predicted from the charge-carrier density dependent model, and
does not follow the expected power-law relationship. The experimental results for these two
amorphous polymers are therefore consistent with a charge-carrier density independent mobility,
and we discuss this in terms of polaron-dominated hopping and interchain correlated disorder.
Date Issued
2016-04-21
Date Acceptance
2016-02-08
Citation
Advanced Functional Materials, 2016, 26 (21), pp.3720-3729
ISSN
1616-3028
Publisher
Wiley
Start Page
3720
End Page
3729
Journal / Book Title
Advanced Functional Materials
Volume
26
Issue
21
Copyright Statement
© 2016 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Subjects
Materials
Chemical Sciences
Engineering
Physical Sciences
Publication Status
Published