An optically activated device that includes an active material on a substrate with two electrodes electrically connected to the active material, the active material conducts current in the presence of light and does not conduct appreciable current in the absence of light. The optically activated device functions as a photodiode, a switch, and an optically gated transistor. The optically activated device conducts current in the presences of light. The active material may be layers of germanium selenide and germanium selenide and an element. Germanium selenide may be sputtered onto a substrate to create layers of material separated by layers of co-sputtered germanium selenide with the element. The active material may be deposited onto a flexible substrate.