- Nano Express
- Open Access
Preparation and Properties of Double-Sided AgNWs/PVC/AgNWs Flexible Transparent Conductive Film by Dip-Coating Process
© Chen et al. 2015
- Received: 20 April 2015
- Accepted: 26 July 2015
- Published: 6 August 2015
The double-sided transparent conductive films of AgNWs/PVC/AgNWs using the silver nanowires and PVC substrate were fabricated by the dip-coating process followed by mechanical press treatment. The morphological and structural characteristics were investigated by scanning electron microscope (SEM) and atomic force microscope (AFM), the photoelectric properties and mechanical stability were measured by ultraviolet–visible spectroscopy (UV–vis) spectrophotometer, four-point probe technique, 3M sticky tape test, and cyclic bending test. The results indicate that the structure and photoelectric performances of the AgNWs films were mainly affected by the dipping and lifting speeds. At the optimized dipping speed of 50 mm/min and lifting speed of 100 mm/min, the AgNWs are evenly distributed on the surface of the PVC substrate, and the sheet resistance of AgNWs film on both sides of PVC is about 60 Ω/sq, and the optical transmittance is 84.55 % with the figure of merit value up to 35.8. The film treated with the 10 MPa pressure shows excellent adhesion and low surface roughness of 17.8 nm and maintains its conductivity with the sheet resistance change of 17 % over 10,000 cyclic bends.
- Double-sided flexible transparent conductive film
- Figure of merit
Touch panels have a great market demand due to their brilliant operation performances [1–3]. As an electrode component for these touch panels, the double-sided transparent conductive film (TCF) with high transparency and conductivity on both sides of a substrate is demanded . Currently, in the preparation process of double-sided transparent conductive films, two single-sided indium tin oxide (ITO) films were prepared firstly, and then the two single-sided ITO films were pasted on the two sides of polyethylene terephthalate (PET) substrate as upper or under circuit [5, 6]. This process is very complicated and prolixity. In addition, due to the high cost and fragility of ITO, there is a demand to replace ITO with other conductive films and develop a new preparation method for double-sided transparent conductive films.
There were transparent conductive films such as metal oxide film, polymer film and carbon nanotubes (CNT), graphene, and metal nanowire films (MNWs) [7–19]. Among these films, the MNWs film was attractive due to its high conductivity and transparency. In particular, the silver nanowires (AgNWs) films are promising for applications in optoelectronic devices resulting from their brilliant electrical, optical, and mechanical characteristics [20–22].
The AgNWs films were usually prepared by the Mayer rod coating [20, 22], vacuum filtration , and transfer-printing [23, 24], etc. Compared with these above processes, the dip-coating process [25–27] was convenient, low cost, and has been used to prepare for various films such as graphene-silver nanowires hybrid films  and carbon nanotubes films . Especially, the dip-coating process is suitable to prepare double-sided coatings at the same time.
For the flexible transparent conductive films, the substrate is an important factor. Up to now, the AgNWs were usually deposited on a PET substrate. As the PVC and PET have a similar surface energy, contact angle and corrosion resistance, therefore, the PVC was used as the substrate for the double-sided AgNWs transparent conductive film in this work. The double-sided transparent conductive film was prepared by the dip-coating process, and the structure, photoelectric properties, and bending performance were also studied.
The AgNWs suspension solution was bought from Coldstone Tech Co., Ltd (Suzhou, Jiangsu, China) with the concentration of 10 mg/mL. The diameter of the nanowires is approximately 70 nm with the length approximately 10~20 μm. The PVC substrate with thickness of 180 μm was washed with deionized water, acetone, or alcohol in ultrasonic vibration for 5 min.
The optical transmittance spectra were investigated by a Beijing PGeneral TU-1900 ultraviolet–visible spectroscopy (UV–vis) spectrophotometer (Beijing Purkinje General Instrument Co., Ltd., Beijing, China) with a blank substrate as the reference. The corresponding sheet resistance was measured using four-point probe technique at room temperature, and the average value was obtained from five measurements for each sample. The surface morphology of the films was observed by a JEOL JSM-7001 field emission scanning electron microscope (SEM; JEOL Ltd., Tokyo, Japan). The surface roughness of the AgNWs was investigated using a MicroNano D3000 atomic force microscopy (AFM; Shanghai Zhuolun MicroNano Instrument Co., Ltd., China). The adhesion performance was measured by 3 M adhesive tape test. The bending performance for the fabricated AgNWs films was determined by measuring the sheet resistance change of the films with the bending cycles at a bending radius of 5 mm, using a machine for reciprocating motion at a speed about 60 cycles/min. The sheet resistance was tested once every 1000 cycles.
Transmittance at λ = 550 nm and corresponding sheet resistance of AgNWs/PVC/AgNWs films with different dip-coating parameters
T 550 (%)
Rs (Ω/sq) side 1
Rs (Ω/sq) side 2
The double-sided transparent conductive films of AgNWs/PVC/AgNWs using AgNWs as conductor and PVC film as substrate were fabricated through facile dip-coating method at room temperature. The photoelectric properties of the films were greatly affected by the coating parameters. When the dipping speed is 50 mm/min and the lifting speed is 100 mm/min, the AgNWs film on both sides of PVC has a sheet resistance of about 60 Ω/sq with the optical transmittance of 84.55 %. The FOM value of AgNWs/PVC/AgNWs film is up to 35.8 that can meet the requirement of touch panels. The film treated with 10 MPa pressing possesses excellent adhesion and low surface roughness, which makes the film have high bending performance with about 17 % change of sheet resistance after 10,000 bending cycles.
This work was financially supported by the National Natural Science Foundation of China (grant No. 51274106, 51474113, 51474037), the Science and Technology Support Program of Jiangsu Province of China (grant No. BE2012143, BE2013071, BE2014850), the Natural Science Research Program of Jiangsu Province Higher Education of China (grant No. 12KJA430001, 14KJB430010), and the Jiangsu Province’s Postgraduate Cultivation and Innovation Project of China (SJZZ15_0131).
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