Deposition of reduced graphene oxide film using drop casting for flexible electronic

Abstract

Graphene and its derivatives such as reduced graphene oxide (rGO) are regarded as promising materials for electrode in flexible electronics platform. Deposition of rGO film onto flexible substrate is the key technology to enable the application of rGO into the flexible electronics system. In this work, the feasibility of a simple drop-casting technique to deposit graphene oxide (GO) onto polyimide film substrate was investigated. The polyimide film is widely used in electronics and can withstand relatively high temperature. This work started with preparation of GO dispersion with different concentration. Prior to drop-casting process, polyimide surface was treated with 1 molar Potassium Hydroxide. The prepared dispersion was drop-casted onto polyimide film which was heated at 80°C. Then, the formed GO film on the polyimide was reduced by means of ascorbic acid and thermal reduction processes at 300°C. The relationship between rGO volume with rGO film properties, namely coverage, thickness and uniformity was investigated using Raman Microscope, Atomic Force Microscopy and 3D Microscope. Drop casting of 1.5 ml GO dispersion produced GO film that covered 50mm x 50mm area. By varying the GO dispersion concentration from 0.025 to 0.1 mg/ml, film with thickness from 16 to 30 nm could be deposited. The average film roughness is around 9.82 nm. After the reduction process, film sheet resistance was analyzed by means of four-point probe measurement. rGO film produced from 0.1 mg/ml dispersion showed sheet resistance as low as 1.36 kΩ/sq. The obtained result showed process feasibility to obtain rGO film with controllable thickness and acceptable conductivity. The developed technique can be further utilized in electronic device fabrication at least at lab scale.