Development of transparent and flexible graphene coated electrode

Abstract

Conductive graphene coated film of rubber silicone polymer was prepared using the facile and simple spin coating technique. Graphene coated films have been studied tremendously worldwide and attracted much attention as they have great potential in flexible optoelectronic applications. Traditionally, Indium Tin Oxide (ITO) have been used for decades as electrodes but high mechanical brittleness of ITO makes it unsuitable for flexible devices. Thus, studies on finding the alternatives for ITO increase by time. In this present work, rubber silicone polymer was used as substrate due to its high transparency and flexibility while graphene was used as coating layer as it has great properties. The main aims of this project include to develop high conductivity electrode together with optimum aforementioned properties. Deposition of graphene solution was varied from 1 to 8 drop. Several parameters were used; dispersion duration (1 & 2.5 hours) and coating speed (500 & 1000rpm) obtain the best sample. Longer sonication time produced better dispersed graphene while lower coating speed resulted in better scattered graphene coating. In the present work, Sample 3 with 3 drops of graphene solution was found to have the best properties among all. Conductivity was set to be the most important property, hence was set as the first screening. The highest current value recorded was 0.2 x 102 A at V=10 meanwhile for flexibility test, current value dropped by 100 times as resistivity increased. As drop number increased, the deposition of graphene on substrate increased causing the formation of graphite from graphene. This resulted in very low conductivity for Sample 6, 7, and 8 with current value ~1 x 10-9A which closed to reference sample with current value ~1 x 1010A. However, results obtained are respectively low compared to electrical properties of graphene from literature which will be further discussed in this report. Optical microscope image shows the presence of graphene but agglomeration was spotted on the substrate which explains the low current value in most samples.