SBIR-STTR Award

At present, the most economically efficient lighting technologies rely on discharge emission from mercury vapors. Mercury, however, is extremely toxic and has the potential to accumulate in the human body over time. The alarming increase in mercury levels in our soils, sediments, and waters is driving the push to find economically viable alternative lighting sources that do not contain mercury. The object of this project is to combine nontoxic doped semiconductor nanocrystal phosphors with existing high-efficiency blue/ultraviolet InGaN light-emitting diodes to produce bright, efficient, and affordable solid state lighting as a replacement for mercury-containing fluorescent lights. Doped semiconductor nanocrystal phosphors that do not contain heavy metals such as lead, mercury, or cadmium are ideal for such an application because, unlike bulk phosphors that suffer from scattering losses, the extremely small size of nanophosphors makes them immune to Mie-type scattering. Also, their synthesis and production methods are relatively cheap and easy, they can be processed from solution in a wide variety of solvents, and they can be blended with polymers and other encapsulants to form highly fluorescent composite materials conformable to nearly any surface. Their emission color can be tunable over a large visible range, and, unlike intrinsic semiconductor nanocrystal emitters, doped nanocrystals have no reabsorption or fluorescence resonance energy transfer losses and, therefore, can be deposited in high-packing densities for maximum luminous output and efficiency. Phase I of this project will concentrate on using our exclusive yellow-orange emitting Mn-doped ZnSe nanocrystal phosphor technology to examine the general feasibility and applicability of this new and exciting technology to the manufacture of solid state lighting that is at least competitive with conventional mercury-containing fluorescent light bulbs in terms of both cost and efficiency. Phase II will focus more on development and synthesis scale-up of a full spectral range of doped semiconductor nanocrystal phosphors with high photoluminescence quantum yields. Phase II also will put more focus onto the commercial aspects, including the development of working prototypes and investor relations. This project, if successful, will have a far-reaching environmental impact. The vision is to replace billions of mercury-containing fluorescent lights with nontoxic nanophosphor solid state lighting units, effectively eliminating a major source of mercury release into the environment. Supplemental

Keywords:
small business, SBIR, EPA, nanocrystal phosphors, mercury, mercury vapors, solid state lighting

There is growing concern about how to limit the release of mercury into the environment. One significant source of mercury is found in fluorescent lamps. Recently, however, compact fluorescent lamps have been heavily promoted in order to conserve electrical energy. While it is true that switching to energy efficient lighting is one of the easiest ways to save energy, reduce CO2 emissions, and save money in the short-term, fluorescent lighting is not the ideal long-term solution precisely because fluorescent lamps contain toxic mercury vapor. Solid state lighting (SSL), on the other hand, holds even greater promise. White LEDs are already more efficient than fluorescent lamps, do not contain heavy metal toxins, and are available with decent color rendering abilities. What holds SSL back is the high price per lumen ration. Only if the cost can be reduced with SSL be able to make significant progress in replacing incandescent and fluorescent lighting. One way to do this is to improve the luminous efficiency of the white LEDs so that more light is emitted at the same price. NN-Labs proposes to complete line of transition-metal doped semiconductor nanocrystals (D-dots) to be used as nanophosphors for white LEDs. Current white LEDs rely on micron-sized phosphors that suffer up to 50% losses in efficiency due to backscattering of fluorescence. Nano-sized phosphors, because they are much smaller than the wavelengths of visible light, do not scatter light. By using D-dots nanophosphors, white LEDs could improve their luminous efficiencies up to 100% compared with bulk phosphors. Furthermore, D-dots are more ideally suited for use in LEDs than other kinds of nanophosphors, such as quantum dots, because D-dots are immune to re-absorption losses that plague intrinsic nanocrystal emitters. This SBIR Phase II project will develop a full spectrum of D-dots emitters with high photoluminescence quantum yields, optimal absorption profiles, and long photo and thermal stability lifetimes required of high brightness (HB) LED phosphors. Also, NN-Labs will work together with its industrial collaborator, Dow Corning, to develop manophosphor/encapsulant composites and fully integrate them into HB LED manufacturing processes. The market for HB LEDs was $4.2 billion in 2006 and is expected to grown to $9 billion in 2009. Estimations show the LED Phosphor market associated with HB white LEDs was $180 million in 2006 and should reach $2.3 billion by 2015. NN-Labs predicts revenue from sales of D-dots to reach $383 million by 2015. Supplemental

Keywords:
Sustainable Industry/Business, Scientific Discipline, RFA, POLLUTION PREVENTION, Technology for Sustainable Environment, Sustainable Environment, Energy, Environmental Engineering, Economics, nanotechnology, nano-phophors, solid state lighting, alternative materials, alternative lighting