Chin. Phys. B Vol. 23, No. 7 (2014) 077202
A novel solution-base self-assembly approach to preparing ultralong
titanyl phthalocyanine sub-micron wires
∗
Zhu Zong-Peng(朱宗鹏)
a)b)
, Wei Bin(魏 斌)
b)
, Zhang Jian-Hua(张建华)
b)
, and Wang Jun(王 军)
b)†
a)
School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China
b)
Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University, Shanghai 200072, China
(Received 21 September 2013; revised manuscript received 8 December 2013; published online 0 X 2014)
Ultralong titanyl phthalocyanine (TiOPc) sub-micron wires have been synthesized by a novel solution-base self-
assembly method. By using different solvents, changing the mass concentration and the solvent vapor pressure, the length
and the shape of the wires can be adjusted. Mixed-phase properties of the TiOPc sub-micron wires were investigated
by ultraviolet–visible (UV–vis) absorption spectrum and X-ray diffraction. Organic transistors based on these wires were
studied and showed the typical p-channel characteristics.
Keywords: titanyl phthalocyanine, sub-micron wire, transistor, solution method
PACS: 72.80.Le, 81.16.Dn, 73.40.Qv DOI: 10.1088/1674-1056/23/7/077202
1. Introduction
Organic semiconductor microstructures have attracted ex-
plosive attention in the context of flexible optoelectronics
[1]
owing to their excellent chemical tenability. These highly or-
dered functional materials with characteristic structures ex-
hibit great potentials in nanoelectric devices such as field-
effect transistors,
[2]
sensors,
[3]
and photovoltaic cells.
[4]
Re-
cently, it has been reported that the π-conjugated molecu-
lar packing in a highly organized microstructure facilitates
the carrier transport and hence improves the performance
of optoelectronic devices.
[5]
In this regard, various strate-
gies have been used to fabricate organic semiconductor mi-
crostructures, including the solution method,
[6]
the phase
transfer method,
[7,8]
chemical vapor deposition,
[9]
surface-
assisted self-assembly,
[10]
the substitution method,
[11–13]
and
so on. Among these methods, the solution method is the most
efficient way to grow nanowires.
[10]
However, from the view-
point of application, it still suffers from tedious procedures,
expensive and specialized equipments, which seriously hinder
its practical application.
Titanyl phthalocyanine (TiOPc) is one kind of non-planar
metal phthalocyanine, which possesses high non-linear opti-
cal sensitivity
[14]
and excellent chemical and thermal stability.
Especially, TiOPc has a large π-conjugated plane that can fa-
cilitate the electron transport,
[15]
which enables it as the ac-
tive layer for the organic thin-film transistor (OTFT). If TiOPc
can be made into a microstructure, it can effectively shrink
the device size for the purpose of high integration and low-
cost manufacture. Driven by this, several groups have made
some progresses on the synthesis of TiPOc microstructure. For
instances, Barbara et al.
[16]
prepared TiOPc nanobelts based
on TiOPc/perylene phenethylimide bilayers. Brinkmann et
al.
[17]
also obtained a uniform α-TiOPc nanobelt by a high-
vacuum deposition of TiOPc onto an oriented poly (tetrafluo-
roethylene) substrate. Unfortunately, to date, microstructures
of metal phthalocyanine have not been prepared by the so-
lution method because they suffer from extreme insolubility
and instability in solvents. Therefore, it is still a challenge to
use the solution method to assemble the TiOPc microstructure
which is expected to exhibit excellent electric properties.
[15,18]
In this paper, we firstly demonstrated a novel solution-
base self-assembly method to prepare high-quality TiOPc sub-
micron wires without the need for surfactants or substitution.
Ultralong TiOPc sub-micron wires about 1 mm in length were
successfully obtained by optimizing the experimental parame-
ters such as the solvent types, the solvent volume, and the mass
concentration. The phase analyses of ultralong TiOPc sub-
micron wires were performed by techniques of ultraviolet–
visible (UV–vis) absorption spectrum and X-ray diffraction
(XRD). Further, the OTFT fabricated in situ on a singular ul-
tralong TiOPc sub-micron wire and its electric properties were
presented.
2. Experiment
2.1. Material
TiOPc was purchased from Aldrich without further pu-
rification. Alcohol, methanol, acetone, and n-hexane were
brought from Sinopharm Chemical Reagent Co., Ltd.
∗
Project supported by the National Natural Science Foundation of China (Grant No. 61176021) and the Innovation Group Project from Shanghai Education
Commission, China.
†
Corresponding author. E-mail: wangj@shu.edu.cn
© 2014 Chinese Physical Society and IOP Publishing Ltd http://iopscience.iop.org/cpb http://cpb.iphy.ac.cn
077202-1