Nanocrystalline Silicon Quantum Dot Light Emitting Diodes Using Metal Oxide Charge Transport Layers

Silicon-based lighting show promise for display and solid state lighting use. Here we demonstrate a novel thin film light emitting diode device using nanocrystalline silicon quantum dots as an emission layer, and metal oxides as charge transport layers. Sputtering deposition conditions for the nickel and zinc oxides were explored in order to balance deposition rate with minimal roughness, optical absorption, and electrical resistivity. Devices displaying characteristic diode current-voltage behavior were routinely produced, although most showed significant reverse saturation current due to the presence of shunts. Current-voltage behavior of devices made in the same batch showed high repeatability, however variations in device performance was observed between batches while the parameters of synthesis were kept constant. Some devices were observed to emit orange-colored light, consistent with photoluminescence behavior of the silicon quantum dots. Photomultiplier tube measurements shows a turn-on voltage of 5V and an exponential increase in light emission with voltage increase.MAS