Provided is an electronic device, such as a flash memory device and/or a write-once-read-once memory device, where the device has a polyoxometallate that is capable of providing and/or accepting one or more electrons. The polyoxometallate may have a Wells-Dawson structure and the polyoxometallate may comprise a cage and optionally one or more guests. Also provided is a method of using the memory device, the method comprising the step of providing to or accepting from the polyoxometalate one or more electrons to provide a polyoxometalate in a reduced or oxidised state.