Advances in Materials Physics and Chemistry, 2013, 3, 299-306
Published Online November 2013 (http://www.scirp.org/journal/ampc)
http://dx.doi.org/10.4236/ampc.2013.37041
Open Access AMPC
Effect of Switching on Metal-Organic Interface
Adhesion Relevant to Organic Electronic Devices
Babaniyi Babatope
1*
, Akogwu Onobu
2
, Olusegun O. Adewoye
3
, Winston O. Soboyejo
2,3
1
Department of Physics, Obafemi Awolowo University, Ile-Ife, Nigeria
2
Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, USA
3
Materials Science and Engineering Department, African University of Science and Technology, Abuja, Nigeria
Email:
*
niyibabatope@gmail.com
Received September 4, 2013; revised October 8, 2013; accepted October 16, 2013
Copyright © 2013 Babaniyi Babatope et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Considerable efforts are currently being devoted to investigation of metal-organic, organic-organic and organic-inor-
ganic interfaces relevant to organic electronic devices such as organic light emitting diode (OLEDs), organic photo-
voltaic solar cells, organic field effect transistors (OFETs), organic spintronic devices and organic-based Write Once
Read Many times (WORM) memory devices on both rigid and flexible substrates in laboratories around the world. The
multilayer structure of these devices makes interfaces between dissimilar materials in contact and plays a prominent
role in charge transport and injection efficiency which inevitably affect device performance. This paper presents results
of an initial study on how switching between voltage thresholds and chemical surface treatment affects adhesion prop-
erties of a metal-organic (Au-PEDOT:PSS) contact interface in a WORM device. Contact and Tapping-mode Atomic
Force Microscopy (AFM) gave surface topography, phase imaging and interface adhesion properties in addition to
SEM/EDX imaging which showed that surface treatment, switching and surface roughness all appeared to be key fac-
tors in increasing interface adhesion with implications for increased device performance.
Keywords: AFM; Interface; Adhesion Force; Organic Electronics; Voltage Switching; Organic Memory Devices;
Surface Treatment
1. Introduction
The investigation of interfaces between dissimilar or-
ganic-metal, organic-organic and organic-inorganic ma-
terials which are inherent in the devices made from them
has been intensified in recent times. The interface phe-
nomena are thus crucial towards the development, under-
standing and improvement of organic-based semicon-
ductor electronic device [1-14] applications such as or-
ganic light emitting devices (OLEDs) [15-18], organic
photovoltaic devices [19-21], organic thin film transistor
devices [22-27] and organic spin electronic devices in
which the transport and control of spin polarized infor-
mation are represented [28-30]. The interface between
the different materials that make them up determines the
charge transport and charge injection efficiency, with
implications for the performance of the devices.
Interfacial phenomena are particularly crucial towards
the development and improvement of applications of
these devices and in order to effectively investigate mul-
tilayer structured devices, the overall flexibility becomes
very critical. This, in addition to their molecular nature,
makes the study of organic thin films interfaces to be
more intensified compared to inorganic semiconductors.
The type of interaction at the interface is either physi-
cal or chemical and progress in organic electronics re-
quires their detail understanding [31]. Investigations of
the chemical nature of interfaces are common in thin film
characterization, but not much attention has been directed
at measuring physical interaction until recently when
advanced characterization tools are becoming more widely
available. However, in a work reported on the nanoscale
adhesion between organic-organic, organic-inorganic, and
inorganic-inorganic thin film interfaces [32], the AFM
technique was used in quantifying the interfaces, though
with some limitations. The pull-off forces and surface
parameters were measured and incorporated into theo-
*
Corresponding author.