Lighting devices with prescribed colour emission

Abstract

Optical conversion layers based on semiconductor nanoparticles for use in lighting devices, and lighting devices including same. In various embodiments, spherical core/shell seeded nanoparticles (SNPs) or nanorod seeded nanoparticles (RSNPs) are used to form conversion layers with superior combinations of high optical density (OD), low re-absorbance and small FRET. In some embodiments, the SNPs or RSNPs form conversion layers without a host matrix. In some embodiments, the SNPs or RSNPs are embedded in a host matrix such as polymers or silicone. The conversion layers can be made extremely thin, while exhibiting the superior combinations of optical properties. Lighting devices including SNP or RSNP-based conversion layers exhibit energetically efficient superior prescribed colour emission

1 . A light conversion layer configured for converting light of a first spectral range to light of at least one second wavelength longer than wavelengths of said first wavelength range; the conversion layer comprising a plurality of semiconductor seeded nanoparticles (SNPs) embedded in a matrix, said SNPs having material composition, geometry and shape selected to convert light of said first spectral range into light of said at least one second wavelength, said conversion layer comprising predetermined refractive index and surface roughness selected to enhance extraction of light of said second wavelength emitted. 
     
     
         2 . The conversion layer of  claim 1 , wherein said SNP comprise rod shapes SNPs (RSNPs) having diameter below 10 nm and a length between 6 nm and 500 nm. 
     
     
         3 . The conversion layer of  claim 1 , wherein said matrix comprises polymer host matrix. 
     
     
         4 . The conversion layer of  claim 1 , wherein said conversion layer further comprises diffusive particles enhancing light scattering within the conversion layer. 
     
     
         5 . The conversion layer of  claim 1 , being configured and operable as a spectral antenna to convert said exciting light of the first spectral range into light of the second wavelengths having balance between different spectral regions such that said light of the second wavelengths is characterized by desired correlated colour temperature (CCT) and color rendering index (CRI). 
     
     
         6 . The conversion layer of  claim 1 , wherein said SNPs comprising SNPs emitting in three or more primary colours with emission bandwidth having full width half max (FWHM) of below 60 nm. 
     
     
         7 . The conversion layer of  claim 1 , wherein said conversion layer comprises one or more sub-layers comprising respectively SNPs different in at least one of material composition, geometry and shape property. 
     
     
         8 . The conversion layer of  claim 1 , wherein said SNPs comprise a core material selected from at least one of the following: CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, GaAs, GaP, GaAs, GaSb, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, AlSb, Cu 2 S, Cu 2 Se, CuInS 2 , CuInSe 2 , Cu 2 (ZnSn)S 4  and Cu 2 (InGa)S 4 . 
     
     
         9 . The conversion layer of  claim 1 , wherein said SNPs comprise a shell material selected from at least one of the following: CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, GaAs, GaP, GaAs, GaSb, GaN, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, AlSb, Cu 2 S, Cu 2 Se, CuInS 2 , CuInSe 2 , Cu 2 (ZnSn)S 4  and Cu 2 (InGa)S 4 . 
     
     
         10 . The conversion layer of  claim 1 , wherein said conversion layer is associated with at least one optical filter located in optical path between the light source and the at least one conversion layer; said at least one optical filter being configured for transmitting exciting light of the first spectral range and reflecting emitted light of the at least one second wavelength range. 
     
     
         11 . The conversion layer of  claim 1 , wherein said conversion layer is associated with at least one transmissive optical element configured for extracting emitted light from said conversion layer towards a desired direction. 
     
     
         12 . The conversion layer of  claim 1 , wherein said first wavelength range comprises at least one of UV and blue wavelength range. 
     
     
         13 . The conversion layer of  claim 1 , configured for use in backlight unit for display device. 
     
     
         14 . The conversion layer of  claim 1 , wherein loading ratio of SNPs embedded in said matrix is greater than 40%. 
     
     
         15 . The conversion layer of  claim 1 , configured for converting input colour mixture light having correlated colour temperature (CCT) in the range of 5000-10000K to provide emitted light having CCT in the range of 2500-6000K.