Monolithic, Solid-State, Plant Lighting Units

Development of a more energy efficient plant irradiance source with high levels of safety, reliability, small volume and mass, and low maintenance would enhance basic plant science research in space and serve as key technology for a Closed Ecological Life Support System(CELSS). Recent advances in semiconductor technology led to development of light emitting diodes (LEDs) capable of high irradiance with electrical efficiencies at least equivalent to other lamps currently used as plant light sources. The LED has other characteristics, such as safety, reliability, long life, and low mass and volume, making it a very desirable irradiance source for space applications. Commercially available LEDs designed as indicator lamps are not entirely satisfactory for plant lighting. Proposed research would fabricate and evaluate alternate methods of mounting semiconductor chips to provide significant electrical efficiencies when operated at high current inputs with conventional discrete LEDs. Increased electrical efficiency would relate to improved heat dissipation from the chips and the geometric dispersion of photons emitted from semiconductor chips. In addition to space applications, highly efficient LED lighting units would find extensive terrestrial commercial applications for hydroponic plant growing operations, household ornamental plant growing, and plant photobiological research.