Interfacial and optoelectronic properties of GnP and CNT/PVDF composite sheets for acoustic actuator with nano-and hetero-structures

Abstract

Nano-and hetero-structures of graphene nanoplatelet (GnP) and carbon nanotube (CNT) can control piezoelectric and optoelectronic properties for acoustic actuator, flexible transparent speaker. Optimized conditions were obtained by obtaining the best dispersion and interfacial durability for the long-term use. Optical transmittance and electrical resistance were measured for GnP and CNT dip-and spraying coating on piezoelectric poly(vinylidene fluoride) (PVDF) sheets with elapsing time under cyclic loading. Uniform dip-coating was simply tried using Wilhelmy plate machine as well as spraying coating. The change in electrical resistance and optical transmittance of coated layer was dependent upon the number of dip-coating, the concentration of nano-solutions. Electric properties of coated layers were measured using fourpoint method and surface resistance was calculated by dual configuration method. Optical transmittance of GnP and CNT coated PVDF sheet was evaluated using UV spectrum. Surface energy and hydrophobicity were investigated by wettability test. As the elapsing time of cyclic loading passed and heating condition right after coating, the stability of surface resistance and thus comparative interfacial adhesion between coated layer and PVDF sheet was evaluated by comparing with the thermodynamic work of adhesion, Wa. As dip-coating number increased, surface resistance of coated sheet decreased, whereas the transmittance decreased steadily due to thicker nano-networking layer. Nano-and hetero-structural effects of GnP and CNT solution on the optical and acoustic response were studied. The thin film transducers showed good acoustic response over wide frequency ranges. Improved interfacial adhesion of was contributed to increase the sound pressure level (SPL) for acoustic actuator.