Selective transfer of mini-light-emitting diodes via the laser-induced switching of adhesives based on azobenzene composites

Abstract

Switchable adhesives are materials that exhibit robust bonding properties under normal conditions but, on the application of specific stimuli, exhibit easy detachability. Of particular interest is their applications in mini/micro-light-emitting diodes (LEDs). However, previous research has focused primarily on the engineering aspect of the transfer processes of these LEDs rather than on the development of switchable adhesive materials. This study presents a novel approach for the development of laser-induced switchable adhesives based on azobenzene composites by incorporating a urethane-modified azobenzene compound and a UV absorber into the adhesive. This approach results in an enhanced adhesion-switching performance and a reduction in laser-induced surface deformation. Furthermore, we investigate the relationship between the adhesion activation behavior and laser exposure conditions to identify the optimal exposure conditions for the laser-induced selective transfer of mini-LEDs. Our findings suggest that azobenzene-composite-based switchable adhesives have significant potential for expanding the material scope of laser-induced adhesion switching and broadening the application field of azobenzene-based switchable adhesives.