Flexible Transparent Electrodes - Lab Video

Meet Yoni, he is a Nanotechnology Honours research student here in the Ellis research abs. He works very hard Hello Yoni So… what are you working on? Ahh grey bits of plastic? Just kidding, are these flexible highly conductive nanocomposite transparent electrodes? But what does that mean exactly? Well you see, transparent electrodes can be used in several devices, for example a solar cell. Here the transparent electrodes needs to allow light to enter the device so that the active layer can produ

ce charges. The transparent electrode then needs to collect these charges, or current, and transfer it out so it can be used. While transparent electrodes can be make of different materials, this one is composed of these nanomaterials each serving a purpose, from the silver nanowire and carbon nanotube matrix providing good conductivity, to the layers of graphene providing a smooth and continuous surface. Hey Yoni Can you show us how you make one of these electrodes? We begin by taking a sheet o

f PEN, which is somewhat similar to laminating paper, and removing its protective films The PEN is then loaded into the spin coater and a graphene oxide solution is deposited on top. This results in a very thin film of graphene oxide on the PEN, so thin in fact that it's hard to see. The PEN and graphene oxide are then heated for several hours to reduce the graphene oxide to graphene Once heating is complete, a mixture of silver nanowires and carbon nanotubes is prepared. A specific ratio of the

se solutions is used as this will alter the properties of the electrode. These solutions are added to a large amount of purified water. This ensures that the concentration is very low which is needed for making a thin film using filtration. A specific film pattern can be made by using a filter mask that only lets the water through the centre. The filter used has a very small pore size allowing only the water to pass but leaves behind the nanowires and nanotubes. After these nanomaterials have de

posited on the filter membrane, they are then transferred on the graphene on PEN sheet using a stamping process. By placing the damp filter membrane face down on top of the PEN and passing it through a large heated laminating machine transfers the filtered pattern on the graphene which is on the PEN, which again is very hard to see. Another larger PEN sheet is used for backing as a support for the electrode. Epoxy, which is a strong adhesive, is used to combine and stick together both of the PEN

sheets. The PEN containing all of the deposited layers is placed face down so that the epoxy can cure and stick to all of the layers. The PEN sheet is once again left to heat so that the epoxy cures and solidifies. After curing the top smaller PEN sheet is carefully and delicately removed. Due to the strong adhesion of the epoxy, all of the layers stay behind with only some graphene coming off. The electrode which is now complete is both very transparent and flexible. It is now time to measure

its conductivity. The electrode is placed under 4 probes that pass a current through the sheet and measure the resistance. These type of electrodes have been found to be very conductive and are very promising. But what exactly could these be used for? One example is transparent displays. Another is for transparent solar cells that can produce electricity. Thank you for watching :)