Unique visible light assisted field emission of tetrapod shaped ZnO/reduced graphene oxide core/coating nanocomposites
The electronic and the optoelectronic properties of graphene based nanocomposites are controllable, making them promising for applications in diverse electronic devices. In this work, tetrapod shaped zinc oxide (T ZnO)/reduced graphene oxide (rGO) core/coating nanocomposites were synthesized by using a hydrothermal assisted self assemble method, and their optical, photoelectric, and field emission properties were investigated. The ZnO, an ideal ultraviolet light sensitive semiconductor, was observed to have high sensitivity to visible light due to the rGO coating, and the mechanism of that sensitivity was investigated. We demonstrated for the first time that the field emission properties of the T ZnO/rGO core/coating nanocomposites could be dramatically enhanced under visible light by decreasing the turn on field from 1.54 to 1.41 V/mm and by increasing the current density from 5 to 12 mA/cm2 at an electric field of 3.5 V/mm. The visible light excitation induces an electron jump from oxygen vacancies on the surface of ZnO to the rGO layer, resulting in a decrease in the work function of the rGO and an increase in the emission current. Furthermore, a field emission light emitting diode with a self enhanced effect was fabricated making full use of the photo assisted field emission process.
Scientific reports