Application of metal nanoparticles to enhance efficiency of nanocrystalline (semiconductor quantum dots) and microcrystalline (rare-earth doped) luminophores

Summary
- Technology is based on polymer films containing metal nanoparticles and phosphor, say semiconductor nanocrystals (quantum dots).[br][/br]- The approach promises 3-10 times increase in luminescence intensity with the same amount of phosphor material (saves cost, owing to smaller amount of phosphor, reduces amount of toxic elements presenting in phosphor, e.g. Cd).[br][/br]- The approach passed through initial research stage and can be adapted to lumionophores.[br][/br]- The approach can be extended towards rare-earth doped microcrystalline phosphors.[br][/br]

Description
Metal nanostructures simultaneously offer incident light concentration and radiative decay enhancement but also enhance nonradiative losses. In case of a perfect emitter with quantum yield =1 (internal quantum efficiency, QE), photoluminescence can be enhanced by means of absorption enhancement overtaking QE losses. For QE<1 (not perfect emitter) luminescence efficiency can be additionally improved by enhancing the QE value. For all emitters metal nanostructures reduce lifetime and if this effect is not accompanied by high QE losses, it can be used to accelerate modulation speed in light-emitting systems. The practical implementation involves fine balance between metal induced enhancement and metal induced non-radiative decay (QE loss) which can be accomplished only by careful selection of metal type, nanoparticle size, density, arrangement and spacing with respect to luminophore particles (nanocrystals or microcrystals, or molecules). Therefore the resulting luminescent product will get the form of a mulilayer composite film on a polymer or on a glass substrate. Semiconductor or dielectric, say sapphire substrates are also feasible.

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Technology Type
 Material

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Technology Benefits
- Plasmonic enhancement of photoluminescence is based on enhancement of light-matter interaction in metal-dielectric nanostructures and involves local incident electromagnetic field amplitude enhancement and enhancement of both radiative and non-radiative decay rates to result in up to 10-fold increase in overall luminescence efficiency (luminescence intensity versus incident external light intensity) with simultaneous decrease in lifetime (response time) provided the optimal topological configuration of metal nanobodies and photoluminescent entities (molecules, quantum dots) are met.[br][/br]- Response time of luminophores becomes shorter by several times enabling faster modulation if necessary (e.g., to enable efficient dimming).[br][/br]- The B.I.Stepanov Institute of Physics of the National Academy of Sciences of Belarus was the first research center in the world to realize experimentally plasmonic enhancement of semiconductor quantum dot luminescence, it has know-how for synthesis of durable metal-covered and phosphor-covered polymer films. Additional research can result in fabrication of polymer film containing metal nanoparticles and phosphor nanoparticles inside the film using phosphors.[br][/br]

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Development Stage
 Applied research
Other: Laboratory techniques of fabrication of metal nanoparticles and their deposition on glass and polymer films have been elaborated, integration of the above films with phosphors (both nano- and microcrystalline) have been performed. Luminescence enhancement has been successfully demonstrated for organic and inorganic luminophores in nanocrystalline form (quantum dots). Preliminary promising results suggest efficient enhancement of luminescence for inorganic microcrystalline phosphors as well. Enhancement of green, yellow, orange, red photoluminescence has been demonstrated. Enhancement of blue photoluminescence can be implemented upon request.

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Intellectual Property Rights
 Secret Know-How
Other: The team from the Institute of Physics holds know-how for synthesis of stable metal nanocomposites integrable with the existing nanocrystalline luminophores on a polymer or a glass substrates. Implementation of the other desirable luminophors and other desirable substrates needs the relevant research.

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Classifier Used at the Enterprise Europe Network
 Materials
 Nano- and Microtechnologies

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Classifier Used at the Technology Transfer Network of yet2.com Inc.
 Materials

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Preferable Regions
 North America
 South America
 Europe
 Asia
 Africa
 Australia

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Type of Collaboration Sought
 R&D Contract

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Available Technical Assistance
 Personnel