Reduction of graphene oxide on polyethylene terephthalate surface by using transmission femtosecond laser

Abstract

Graphene has great application prospects in electronic chips and sensors due to its excellent electrical and thermal conductivity. Many methods have been reported to generate graphene, among which the use of a laser to irradiate graphene oxide (GO) surface is capable of reducing and patterning GO simultaneously. To date, the sheet resistance of laser reduced graphene oxide (LRGO) in the air is somewhat high. In this paper, we report a new method for GO reduction by femtosecond laser transmitting from the GO-free side of polyethylene terephthalate (PET). Under this technique, the sheet resistance of 75 Ω/sq, one of the lowest in the air, is obtained. The mechanism of sheet resistance evolution is examined. In a low laser power range, removing oxygen-containing groups by breaking C-O bonds plays a major role in sheet resistance dropping. When laser power rises to a high range, the removal of oxygen-containing groups and the conversion of sp3 to sp2 hybridized carbon work simultaneously. Meanwhile, the influence of PET substrate has been taken into consideration. More interestingly, LRGO could expand up to 610% in height. In addition, the adhesion between LRGO and PET reaches the 5B level, further proving its essential bonding property for flexible electronics.