Study Of Metal-mesh Transparent Conductive Film And Its Application

Transparent conductive films(TCFs)play an indispensable role in optoelectronic devices because of high conductivity and high optical transmittance.Nowadays,optoelectronic devices are evolving towards large area,lightness,low cost,flexibility and stretchability.The demand for high-performance flexible and stretchable TCFs is growing rapidly.At present,the widely used transparent conductive material is ITO,but its brittleness limits its application for flexible devices.Many alternatives to ITO have been developed,such as conductive polymer,carbon materials and metallic nanomaterials.The metal-mesh approach has come out as a winner due to its high conductivity and optical transmittance,as well as flexibility.The conventional technology for making metal-mesh TCFs relays on complicated lithography and etching processes,which is costly and environmental unfriendly.In our research group,an embedded silver metal-mesh TCF by hybrid printing has been independently developed.It can achieve high conductivity and high optical transmittance.And it has been successfully applied in the touch panel and industrialized.On the basis of the technology,low-cost,high-performance,high-aspect-ratio and stretchable metal-mesh TCFs have been developed and studied in this paper.In addition,further application study has been focused on the flexible and stretchable devices.1.The smooth surface for transparent conductive electrode used in optoelectronic devices plays a crucial role.A novel approach to making metal-mesh transparent conductive electrode with extremely smooth surface has been proposed that is based on electroplating of nickel(Ni)and polishing technologies.The fabricated Ag/Ni metal-mesh transparent conductive electrode has an extremely low surface roughness of 0.17 nm,a low sheet resistance of 2.1 ?/?,and a high transmittance of 88.6%.In addition,Ag/Ni metal-mesh transparent conductive electrode shows outstanding mechanical flexibility and environmental stability at the condition of high temperature and high humidity.It is also used for the flexible quantum dot light emitting diodes and perovskite solar cells,achieving good device performance.2.In order to reduce the material cost and the time of thermal sintering,copper nanoparticles and the millisecond flash sintering method are developed for fabricating metal-mesh TCF.A Cu/Sn hybrid ink has also been developed by mixing Cu and Sn particles to further reduce the energy of flash sintering.The sintering energy of Cu/Sn hybrid films were decreased by 21%compared to sintering pure Cu film,which is attributed that Sn particles with the lower melting point were effectively fused among Cu particles and formed conducting path between particles.The hybrid printed Cu/Sn metal-mesh TCF have been achieved with less defects and better film quality compared with pure copper metal-mesh TCF.3.The metal-mesh TCFs already reported have many disadvantages,such as low aspect ratio,low resolution and low optoelectronic performance,which is difficult to meet the requirements of large-area practical application.A high-performance Cu metal-mesh TCF with the highest FOM of up to 8×104 ever reported has been presented by additional manufacturing process of blading a silver seed layer and selectively electroplating of Cu.This embedded Cu metal-mesh exhibits an ultra-low sheet resistance of down to 0.03 ?/? at the transmittance of 86%.It is simultaneously demonstrated that Cu metal-mesh has remarkable mechanical flexibility,high environmental stability at high temperature and high humidity,and durability in repeated heating cycles.Cu metal-mesh as a flexible heater also presents a rapid heating response at low operating voltages and attached to a car windshield,effectively removing the snow.It is also used in transparent electromagnetic shielding film,achieving high electromagnetic interference shielding efficiency more than 40 dB during 300 MHz-18 GHz.4.With the development of wearable electronic devices,stretchable transparent conductive electrodes have been widely used.Combined with electroplating and peeling-off technology,the 1D and 2D stretchable transparent conductive electrodes based on Cu metal-mesh have been developed.The stretchable performance and the tensile mechanism of Cu metal-mesh transferred on different stretchable substrates has been studied,such as semipermeable substrate,PDMS and ecoflex.By characterization of 2D stretchable transparent conductive electrode,it has good optoelectronic performance and the sheet resistance is 0.1 ?/? at the optical transmittance of 82%.The stretchable transparent conductive electrode with higher amplitude zigzag structure can keep stable conductivity at 150%tensile strain,showing excellent stretchable performance.The stretchable metal-mesh transparent conductive electrode is used in the stretchable transparent heater,which has outstanding heating efficiency and stability.