Colorless luminescent solar concentrators using colloidal semiconductor nanocrystals

Abstract

Disclosed herein are embodiments of a composition comprising a polymer or sol-gel and one or more nanocrystals. The composition is useful as a luminescent solar concentrator. The nanocrystals are dispersed in the polymer or sol-gel matrix so as to reduce or substantially prevent nanocrystal-to-nanocrystal energy transfer and a subsequent reduction in the emission efficiency of the composition. In some embodiments, the polymer matrix comprises an acrylate polymer. Also disclosed herein is a method for making the composition. Devices comprising the composition are disclosed. In some cases the polymer is the waveguide, in others the polymer is applied as a coating on a waveguide. In some examples, the device is a window.

We claim: 
     
         1 . A substantially transparent composition, comprising:
 a transparent matrix; and   plural, substantially non-aggregated heavy metal free nanocrystals substantially homogeneously dispersed in the transparent matrix and separated by a distance greater than an energy transfer distance.   
     
     
         2 . The composition of  claim 1 , wherein the heavy metal free nanocrystals do not comprise cadmium, mercury, arsenic or lead. 
     
     
         3 . The composition of  claim 1 , wherein the heavy metal free nanocrystals comprise a core and at least one shell. 
     
     
         4 . The composition of  claim 3 , wherein the shell comprises a shell material and the shell material is selected to enhance the stability of the core, to enable the nanocrystals to be dispersed in a matrix without substantially quenching the quantum yield of the nanocrystals, to maintain or improve the photoluminescent intensity of the nanocrystal, or a combination thereof. 
     
     
         5 . The composition of  claim 1 , wherein the transparent matrix is a polymer matrix, sol-gel matrix, glass matrix, solvent matrix, or combination thereof. 
     
     
         6 . The composition of  claim 5 , wherein the transparent matrix is a polymer matrix comprising a polymer selected from poly acrylate, poly methacrylate, polyolefin, poly vinyl, epoxy resin, polycarbonate, polyacetate, polyamide, polyurethane, polyketone, polyester, polycyanoacrylate, silicone, polyglycol, polyimide, fluorinated polymer, polycellulose, poly oxazine, or combinations thereof. 
     
     
         7 . The composition of  claim 5 , wherein the polymer matrix comprises an acrylate polymer. 
     
     
         8 . The composition of  claim 7 , wherein the acrylate polymer comprises polylauryl methacrylate. 
     
     
         9 . The composition of  claim 1 , wherein the nanocrystal comprises zinc sulfide, zinc selenide, zinc oxide, zinc telluride, aluminum nitride, aluminum sulfide, aluminum phosphide, aluminum antimonide, gallium nitride, gallium phosphide, gallium antimonide, indium nitride, indium phosphide, indium antimonide, thallium nitride, thallium phosphide, thallium antimonide, indium gallium nitride, indium gallium phosphide, aluminum indium nitride, indium aluminum phosphide, aluminum gallium phosphide, aluminum indium gallium nitride, silver indium selenide sulfide, gold indium selenide sulfide, copper aluminum selenide sulfide, copper gallium selenide sulfide, silver indium selenide, gold indium sulfide, copper aluminum selenide, copper gallium selenide, copper indium selenide sulfide, Si, Ge, Sn, SiGe, SiSn, GeSn, aluminum, gold, silver, cobalt, iron, nickel, copper, gallium, silicon, manganese, indium, selenium, sulfur or combinations thereof. 
     
     
         10 . The composition of  claim 1 , wherein the nanocrystal has a core/shell structure selected from InP/ZnSe, InSb/ZnSe, InP/ZnS, InSb/ZnS, Ge/Si, Si/Ge, Sn/Si, Si/Sn, Ge/Sn, Sn/Ge, AgInSe x S 2-x /ZnS, AuInSe x S 2-x /ZnS, CuAlSe x S 2-x /ZnS, CuGaSe x S 2-x /ZnS, CuInSe x S 2-x /CuInS 2 , CuInSe x S 2-x /AuGaS 2 , or CuInSe x S 2-x /ZnS, where x is from 0 to 2. 
     
     
         11 . The composition of  claim 1 , wherein a concentration of nanocrystals in the transparent matrix is from greater than zero wt % to 10 wt % relative to the weight of the transparent matrix. 
     
     
         12 . The composition of  claim 1 , wherein the nanocrystals are dispersed in the transparent matrix such than a nanocrystal emission efficiency drops by less than 10% compared to a nanocrystal emission efficiency of nanocrystals dissolved in a solvent. 
     
     
         13 . The composition of  claim 1 , wherein the composition has a color rendering index of from 80 to 100, an optical power conversion ratio of greater than 1%, absorbs at least 10% of incident solar light, or a combination thereof. 
     
     
         14 . The composition of  claim 1 , wherein the nanocrystals have a core/shell structure of CuInSe x S 2-x /ZnS, where x is from greater than 0 to less than 2. 
     
     
         15 . A composition substantially transparent to visible light, IR light, UV light, or a combination thereof, the composition, comprising:
 a polymer matrix wherein the polymer is selected from poly acrylate, poly methacrylate, polyolefin, poly vinyl, epoxy resin, polycarbonate, polyacetate, polyamide, polyurethane, polyketone, polyester, polycyanoacrylate, silicone, polyglycol, polyimide, fluorinated polymer, polycellulose, poly oxazine or combinations thereof; and   plural, substantially non-aggregated heavy metal free nanocrystals substantially homogeneously dispersed in the polymer matrix at a concentration of from greater than zero wt % to 1 wt % relative to the weight of the polymer matrix such that a nanocrystal emission efficiency drops by less than 10% compared to a quantum dot emission efficiency of nanocrystals dissolved in a solvent, the core/shell structure being selected from InP/ZnSe, InSb/ZnSe, InP/ZnS, InSb/ZnS, Ge/Si, Si/Ge, Sn/Si, Si/Sn, Ge/Sn, Sn/Ge, AgInSe x S 2-x /ZnS, AuInSe x S 2-x /ZnS, CuAlSe x S 2-x /ZnS, CuGaSe x S 2-x /ZnS, CuInSe x S 2-x /CuInS 2 , CuInSe x S 2-x /AuGaS 2 , or CuInSe x S 2-x /ZnS, where x is from 0 to 2, the nanocrystals having a global Stokes shift of greater than 200 meV and being separated by a distance greater than an energy transfer distance;   wherein the composition has a color rendering index of from 90 to 100.   
     
     
         16 . A device, comprising the composition of  claim 1 . 
     
     
         17 . The device of  claim 16 , wherein the transparent matrix is a matrix transparent or semi-transparent to visible light, infrared light, ultraviolet light or a combination thereof. 
     
     
         18 . The device of  claim 16 , comprising a transparent substrate at least partially coated with a film comprising the composition. 
     
     
         19 . The device of  claim 18 , wherein the transparent substrate is a glass substrate. 
     
     
         20 . The device of  claim 16 , further comprising a photovoltaic, a reflector, a diffuser, or a combination thereof. 
     
     
         21 . The device of  claim 16 , wherein the device is a window. 
     
     
         22 . The device of  claim 21 , wherein the window comprises at least one window pane comprising the composition, at least one window pane at least partially coated with a film comprising the composition, at least two window panes with the composition positioned between the window panes, or a combination thereof. 
     
     
         23 . The device of  claim 16 , wherein the nanocrystals have a core/shell structure of CuInSe x S 2-x /ZnS, where x is from 0 to 2. 
     
     
         24 . The device of  claim 16 , wherein the device has a color rendering index of from 80 to 100. 
     
     
         25 . A method for making a composition, comprising:
 dispersing heavy metal free nanocrystals in a first amount of a monomer and a first polymerization initiator to form a dispersion of quantum dots in monomer;   mixing the dispersion of quantum dots in monomer with a second amount of the monomer and an initiator to form a mixture;   agitating the mixture; and   initiating polymerization of the monomer to form the composition comprising a transparent matrix with quantum dots dispersed within.   
     
     
         26 . The method of  claim 25 , further comprising allowing the polymerization to proceed in the dark.