Efficient Hybrid Phosphors for Blue Solid State Light Emitting Diodes

72261S03-I Currently, only one type of phosphor (YAG-based) is available for converting light from a blue LED to white, thereby enabling solid state white light. However, the YAG-based phosphor has color deficiency in the red and blue-green, and, moreover, there are international patent issues regarding the use of the material in solid state lights. This project will develop alternative novel phosphor materials based on a hybrid organic/inorganic system with far superior performance to the YAG. Existing UV-efficient silicate phosphors will be modified to allow blue light absorption and broadband emission in the yellow-green. Then, hybrid organic/inorganic compounds will be developed and optimized, with the end result being a novel blue-to-white converting material with performance far exceeding the current state of the art. Phase I will demonstrate the feasibility of the phosphor system to efficiently convert blue emission (470 nm) from an LED into white, thereby providing a white LED with a luminous efficiency of 30 lumens per watt (twice that of incandescent bulbs) and a color rendering index (CRI) over 80. The Phase II goal is a white LED with a luminous efficiency greater than 50 lumens per watt and a CRI over 90. Commercial Applications and Other Benefits as described by awardee: The availability of efficient white LEDs should open up a number of exciting new application markets: white light sources to replace traditional incandescent and fluorescent light bulbs, efficient low-voltage backlights for portable electronics, etc. The down-converting hybrid phosphor materials also could be used to make pixelated screens for full-color, photonically-driven displays, and even used in maintenance-free, LED-based traffic lights. Furthermore, the impact on the environment would be dramatic, resulting in reduced energy consumption and the elimination of fluorescent lamp waste, one of the main sources of mercury pollution.