Osaka, Japan – Matsushita Electric Works developed the world’s first^*1 discharge-free fluorescent lighting device using a nanocrystalline silicon cathode^*2 through its collaborative research with Professor Nobuyoshi Koshida of the Department of Electrical and Electronic Engineering, Tokyo University of Agriculture and Technology. It is expected to be applied in future highly efficient, mercury-free, environment-friendly lighting fixtures.

Unlike the conventional fluorescent lamp which discharges a mercury-containing gas, this new technology allows emission of vacuum ultraviolet (VUV) light^*3 from xenon molecules^*4 to excite a phosphor without the need for an electric discharge or mercury. The use of a nanocrystalline silicon cathode, which can supply highly energetic electrons to a gas ambient, was the key to realizing the world’s first discharge-free fluorescent lighting device. Since an electric discharge is unnecessary in the new technology, it can use energy more efficiently. In theory, an efficacy of 150 lm/W can be expected, exceeding the efficacy of existing fluorescent lamps.

The expected application of the technology will be new environment-friendly lighting fixtures including high-efficiency, high-luminosity, flat-panel mercury-free lighting fixtures. The company will continue developing this technology to improve its performance by elucidating the light emission mechanism and optimizing the device structure.

The technology will be described in detail at the 21st International Vacuum Nanoelectronics Conference to be held in Poland on July 13 through 17.

When a voltage is applied to the nanocrystalline silicon cathode, it generates electrons which are released into xenon gas to directly excite xenon molecules.^*5 The resulting VUV light is absorbed by the phosphor and converted into visible light.