Abstract
Many studies have been conducted to fabricate unique structures on flexible substrates and to apply such structures to a variety of fields. However, it is difficult to produce unique structures such as multilayer, nanospheres and porous patterns on a flexible substrate. We present a facile method of nanospheres based on laser-induced porous graphene (LIPG), by using laser-induced plasma (LIP). We fabricated these patterns from commercial polyimide (PI) film, with a 355 nm pulsed laser. For a simple one-step process, we used laser direct writing (LDW), under ambient conditions. We irradiated the PI film at a defocused plane −4 mm away from the focal plane, for high pulse overlap rate. The effect of the laser scanning speed was investigated by FE-SEM, to observe morphological characterization. Moreover, we confirmed the pattern characteristics by optical microscope, Raman spectroscopy and electrical experiments. The results suggested that we could modulate the conductivity and structural color by controlling the laser scanning speed. In this work, when the speed of the laser is 20 mm/s and the fluence is 5.28 mJ/cm2, the structural color is most outstanding. Furthermore, we applied these unique characteristics to various colorful patterns by controlling focal plane.
Highlights
Graphene has a single layer, in which a thin layer of carbon has important properties, including a high optical transmittance and electrical conductivity, which make it favorable for use in optoelectronic applications [1,2,3,4]
We present, for the first time, graphene flakes and graphitization patterns based on laser-induced porous graphene (LIPG) with nanospheres which showed structural colors based on reflectance of the graphene multilayers and the high conductivity of the 3D carbon network
Our patterns patterns with nanospheres were fabricated by irradiating them onto the commercial PI film
Summary
Graphene has a single layer, in which a thin layer of carbon has important properties, including a high optical transmittance and electrical conductivity, which make it favorable for use in optoelectronic applications [1,2,3,4]. On polyimide (PI) film, of which the 2D peak is centered at 2700 cm−1 , like single-layer graphene, is an alternative, because it can be produced quickly and inexpensively, and it is easy to fabricate patterns with it [7,8,9,10,11]. The interaction of PI and the laser is broadly classified as a delamination effect or a carbonization effect, and it is closely related to the laser fluence [12,13,14].
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