Light-induced electrical switch via photo-responsive nanocomposite film

Photo-responsive nanomaterials have attracted a lot of attention since they allow a remote control with a non-invasive stimulus—light. Owing to this property, it has been applied to next-generation electrical devices, which are desired to be flexible and transparent for a wider range of applications. Herein, we developed a flexible, transparent and conductive film which can change its shape via light of specific wavelength to control the electrical conductivity between electrodes. The film is composed of three layers: azobenzene incorporated poly(dimethylsiloxane), AzoPDMS; silk fibroin; and silver nanowires, AgNWs. When azobenzene within the polymer changes its molecular arrangement upon irradiation, the difference in volume changes of AzoPDMS and silk fibroin layer results in the film to bend. Since a silk fibroin layer folds inward upon irradiation, AgNWs are coated onto the silk fibroin layer to be selectively in contact with the electrodes. This photo-responsive nanocomposite film is flexible, transparent and conductive which can be connected to the circuit on demand via light acting as an electrical switch. We believe it can be combined with various transparent electronic devices to further expand its applications.