Title: Large-Scale Stretchable Semi-Embedded Copper Nanowires Transparent Conductive Films by Electrospinning Template
Author: Xia Yang, Xiaotian Hu, Qingxia Wang, Jian Xiong, Hanjun Yang, Xiangchuan Meng, Licheng Tan, Lie Chen, and Yiwang Chen
Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
With recent emergence of wearable electronic devices, the flexible and stretchable transparent electrodes are the core components to realize innovative devices. Copper nanowires (CuNWs) network is commonly chosen because of its high conductivity and transparency. However, the junction resistances and low aspect ratios still limit its further stretchable performance. Herein, a large-scale stretchable semi-embedded CuNWs transparent conductive film (TCFs) was fabricated by electrolessly depositing Cu on the electrospun poly (4-vinylpyridine) (P4VP) polymer template semiembedded in polydimethylsiloxane (PDMS). Compared with traditional CuNWs which as-coated on the flexible substrate, the semi-embedded CuNWs TCFs showed low sheet resistance (15.6 Ω sq-1 at ∼82% transmittance), as well as outstanding stretchability and mechanical stability. The light-emitting diode (LED) connected the stretchable semi-embedded CuNWs TCFs in the electric circuit still lighted up even after stretching with 25% strain. Moreover, this semi-embedded CuNWs TCFs was successfully applied in the polymer solar cells as stretchable conductive electrode which yielded a power conversion efficiency of 4.6% with 0.1 cm2 effective area. The large-scale stretchable CuNWs TCFs show potential for wearable electronic devices development.
Keywords: Copper nanowires; Stretchability; Transparent electrodes; Electroless deposition; Polymer solar cells
Selections: Preparation of semi-embedded P4VP nanowires. First, the PDMS elastomer substrate with thickness of 40 µm was prepared by mixing sylgard 184 “base” and “curing agent” with a weight ratio of 10:1, spin-coating the mixture solution with a speed of 500 rpm for 10 s and 1000 rpm for 30 s on the PET substrate, and pre-curing at 60 °C for 15 min. Second, electrospun P4VP NWs were prepared semi-embedded into the pre-curing PDMS film. 15 wt% of P4VP in dimethylformamide:ethanol solution (1:1, v/v) was loaded in a 10 mL syringe with a needle tip, which was connected to an electrospining machine (QZNT-E04, Foshan Lepton Precision Measurement and Control Technology Co., Ltd). The applied potential onto the needle was 8.1-9.7 kV. The collector was grounded tin-foil, and the PDMS substrate was placed on the foil to collect P4VP NWs. The distance between the syringe needle tip and the collector was 15 cm, and the pump rate was 0.6 mL/h. High electrical field and surface charges pulled P4VP NWs out of the droplet, and the NWs were attracted onto the collector due to electrical force. Finally, the pre-curing PDMS film with semi-embedded P4VP NWs was placed at 80°C for curing 1 h.