Femtosecond laser-induced ultrafast growth of volcanic-shaped graphene micropillars

Abstract

Surface micropillars are capable of significantly altering material properties, including anti-reflection, structural color, wettability, and adhesion. Conventional methods for fabricating micropillars are both time-intensive and material-consuming. Recently, a nature-inspired light-induced self-growth method has been proposed to avoid the drawbacks of conventional methods. However, this method suffers from slow growth rates (slower than 3.3 × 102 μm/s) and restricted precursor material (limited to heat-shrinkable shape-memory polymer). Herein, we developed the light-induced method based on femtosecond laser thermal accumulation engineering and realized the self-growth of micropillars on thermal-stable polymers. By inducing localized carbonization rather than heat shrinkage with a high repetition rate laser, given the instantaneous release of large amounts of gases and highly localized stresses during laser carbonization, unique graphene micropillars grow rapidly and spontaneously from the polyimide surface with a growth rate of 4.5 × 103 μm/s. The growth rate of micropillars is increased by an order of magnitude compared to previously reported light-induced methods. Furthermore, the dimensions of these micropillars, including height, diameter, and spacing, can be precisely controlled by modulating the heat accumulation. Last but not least, solar absorbers and light-driven actuators are flexibly fabricated using this method, demonstrating its practical applicability.