Three‐Dimensional Writing of Conducting Polymer Nanowire Arrays by Meniscus‐Guided Polymerization

Abstract

Organic electronics increasingly impacts our everyday life with a variety of devices such as displays for TV or mobile appliances, smart cards and radio-frequency identifi cation (RFID) tags. [ 1 , 2 ] This blossoming domain could greatly profi t from effective ways to fabricate conducting or semiconducting organic nanowires. [ 3 ] Specifi cally, the three-dimensional (3D) and individual integration of each nanowire is essential [ 4 ] for many new device concepts, but so far this was not possible. Here we show the demonstration of accurate and versatile 3D direct writing of conducting polymer nanowires based on guiding a monomer meniscus by pulling a micropipette during oxidative polymerization. This is an important step for organic electronic integration with high density and enhanced freedom in circuit design.Conducting polymers such as polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) are very interesting materials because they combine tunable electrical transport characteristics and excellent mechanical properties. [ 5 ] In particular, conducting polymer nanowires are quite important for a broad range of nanodevices such as fi eld effect transistors, [ 3 ] bio-and chemical sensors, [ 6 , 7 ] and non-volatile memories. [ 8 ] Such nanowires are fabricated by soft lithography, [ 9 , 10 ] dip-pen lithography [ 11 ] and electrospinning. [ 12 ] However, these methods are still limited to in-plane patterning of low-aspect-ratio nanowires, whereas for advanced applications 3D patterning is essential.Direct ink writing and probe-based drawing are used for 3D wire patterning. The fi rst method, based on the extrusion of concentrated ink through a nozzle, was applied for 3D microfabrication with metals, oxides, and polymers. [13][14][15][16] However, bringing the wire diameter below micrometer-level is not easy due to the size and concentration of the ink particles. Probe-based drawing can fabricate polymer nanowires. [ 17 ] However, high-density integration is limited by the large pre-deposited polymer droplet (a few tens to hundreds of micrometers).An alternate technique for 3D electrodeposition was recently developed: writing nanowires with a nanoscale electrolyte meniscus. [ 18 , 19 ] This method was so far demonstrated for 3D metallic nanowires but not for conducting polymers.Here we show that this type of technique can in fact be used for conducting polymers offering high accuracy, excellent versatility and marked advantages with respect to alternate solutions. In essence, we obtained a stretched monomer meniscus by pulling a micropipette fi lled with a Py solution, exploiting oxidative polymerization in air. The wire radius so produced was accurately controlled down to ∼ 50 nm by tuning the pulling speed.The technique was successfully tested with specifi c focus on essential features for advanced organic nanodevice integration. Specifi cally, we produced dense arrays of different types of freestanding nanocomponents: straight wires, complex-shape wires, branche...

Scanning Electrochemical Cell Microscopy: A Versatile Technique for Nanoscale Electrochemistry and Functional Imaging

“…Recent studies have used single-barreled pipettes, which have no positional feedback mechanism, to construct copper and platinum wires (87), conducting polymer structures (88,89), and individual microcrystals (90). Theta pipettes have previously been used to construct patterns of biomolecules (53) …”

Polymer/Carbon Nanotubes (CNT) Nanocomposites Processing Using Additive Manufacturing (Three-Dimensional Printing) Technique: An Overview

“…% via meniscus-guided printing method [83]. In this method, CNT aqueous ink was composed of MWNTs and polyvinylpyrrolidone (PVP).…”

Individually Addressable Suspended Conducting‐Polymer Wires in a Chemiresistive Gas Sensor

“…The FPL technique enabled omnidirectional wire growth, site-specifi c positioning, and modifi cation of electrical properties, and it was particularly effective for 3D integration. [ 16,17 ] When the micropipette touched the substrate, a meniscus of the PEDOT:PSS solution was created outside its opening (diameter ≈ 0.8 μm). As the micropipette was retracted by 250 nm stepwise pulling (pulling speed of 0.5 μm s −1 ), the meniscus was stretched, and its cross section reached 0.8 μm.…”

“…[ 16,17 ] An aqueous solution of PEDOT:PSS (1.3 wt% in H 2 O; Aldrich) was used as an ink to fabricate arched submicron wires. The ink was used without further purifi cation.…”