The Research On Key Technologies Of Flexible Transparent Electrodes

The transparent conductive electrode(Transparent Conducting Electrode, TCE) is one of the main components of the photovoltaic device such as solar cell, the LCD display, OLEDs, touch screen, an organic EL panel. Currently,due to the good optical properties, indium tin oxide(Indium Tin Oxide, ITO) is widely used in the touch screen mobile phones, car navigation systems, TVs, computer monitors and so on. However, ITO is weak in chemical and thermal stability, ITO is of high price, the brittlless of ITO materials and In is toxic components of ITO,only 3% to 30% In can be effectively utilized in the process of the high-temperature magnetron sputtering, these deficiencies have led ITO can not meet future power optoelectronic: flexible,lightweight, cheap, environmentally friendly and other more strict requirements.The transparent conductive film such as carbon nanotubes, metal films, graphene has attracted attention of researchers, but the light transmittance, conductivity, stability can not meet the needs of the transparent electrode.To solve the current problems, in this paper we use the finite element simulation software Comsol Multiphysics to design the strcture and determine the material of metal grid, and study the optoelectronic properties of metal mesh. Then using photolithography process for the preparation of flexible silver grid(Ag-grid) transparent electrode, using the two-terminal method to measure the sheet resistance and obtain the sheet resistance value can low to 4.1?/sq, and the ultraviolet-visible spectrophotometer measure the light transmittance in the visible range can up to 95.2% regardless of the substrate.In addition, the transparent electrode is with good flexibility, after bending 1,000 times the sheet resistance increased only 11.8%. Then, we apply the flexible Aggrid transparent electrode with the period is 505 um to flexible four-wire resistive touch screen by using screen printing techniques, and through the control card and driver to realize the control of computer.The flexible Ag-grid transparent electrode is unstable and susceptible to oxidation, therefore we use the graphene prepared by CVD to cover on the Ag-grid to improve the stability of the Ag-grid transparent electrode. In our experiment, we prepared graphene /Ag-grid hybrid transparent electrode, then use four-point probe and UV-visible spectrophotometer to characterize the optical performance. Though the transmittance of Ag-grid decreased by 3%~4%,when we put the transparent electrode in the harsh environment with 80% RH, and 70℃ high-temperature, after 4 hours the sheet resistance of Ag-grid increased by 29.1%, while the graphene/Ag-grid transparent electrodes increased by only 8.7%, the experimental results shows that the graphene improved the environmental adaptability of Ag-grid.We also find that the performance of graphene is improved as well, the sheet resistance of graphene is 1638.1?/sq, and the transmittance is 87% before transferring, when transferred the graphene onto the Aggrid with 100×100×5um the sheet resistance is reduced to 25.1?/sq, which lower the sheet resistance of graphene by about two orders of magnitude.