Preparation And Properties Of Silver Nanowire/Polyimide Flexible Transparent Composite Film

In recent years,the transparent conductive electrode（TCE）film has been highly regarded for its high light transmittance and conductivity.Optoelectronic devices in the form of TCEs,such as light-emitting diodes,solar cells,and touch screen panels,have played a vital role in practical production.In the past,indium tin oxide（ITO）with high light transmittance and low sheet resistance has been widely used as TCE.However,with the increasing demand for miniaturized flexible portable devices,ITO cannot meet application requirements due to its nature brittleness,poor flexibility,and high cost.Among many substitutes,silver nanowires（AgNWs）is regarded as one of the most promising candidates to replace ITO because of its good conductivity,high light transmittance and good flexibility.On the other hand,when AgNWs is applied to TCE,since thin film photovoltaic devices are particularly sensitive to surface roughness of AgNWs,it is necessary to employ polymers to fill and level the AgNWs conductive network to improve the surface roughness.Among many flexible polymer substrates,transparent colorless polyimide（CPI）has many outstanding advantages such as excellent optical transparency,outstanding flexibility and excellent thermal stability,making it the most promising microelectronics device substrate.Therefore,the TCE film formed by the combination of AgNWs and CPI substrate has great research significance and application potential.Based on this point,AgNWs/CPI flexible transparent composite film with excellent performance was prepared and its performance and application were studied.The research contents are as follows:First,the CPI film with outstanding optical transparency was prepared based on the6FDA/TFB monomers.The ionic liquid（IL）was further incorporated the above system to prepare the corresponding CPI composite film.The transmittance of this CPI composite film at 550 nm is as high as 90.4%,the tensile strength is 51.9 MPa,and the elongation at break reaches 113.2%.Next,AgNWs with a large aspect ratio and the above-mentioned CPI composite film were combined to prepare an AgNWs/CPI flexible transparent composite film with excellent comprehensive performance.Since AgNWs was semi-embedded in the CPI film,the adhesion between AgNWs and CPI film is improved.Among them,the optimized AgNWs/CPI flexible transparent composite film shows excellent conductivity（sheet resistance is 24.0Ω/sq）,while maintaining good optical transparency（transmittance at 550 nm is 81.5%）.When connected in series in a simple circuit and bent at a large angle,the brightness of the LED small bulb does not change and there is no flicker.The resistance of the thin film after 5000 times of cyclic bending is only 23%higher than the initial value.Finally,the optimized AgNWs/CPI flexible transparent composite film was introduced into the preparation of supercapacitor（SC）flexible electrodes.Following the idea of embedded structure,a novel"inverted load"preparation strategy is proposed to prepare high-performance flexible W_0.71Mo_0.29O₃/PEDOT:PSS/AgNWs/CPI（WPAC）electrode,which has a high specific capacitance of 15.8 mF cm^-2 at a current density of 0.1 mA cm^-2.At the scan rate of 100 mV s^-1,the capacitance retention rate remains 92%after 10,000 CV cycles.The sheet resistance of the electrode increases less than 1%after 10,000 times of bending with a radius of curvature of 500μm.These data demonstrated that the novel electrode possesses excellent flexibility,electrochemical performance,cyclic and bending stability.