Composition and method of preparing nanoscale thin film photovoltaic materials
A photo-absorbing layer for use in an electronic device; the layer including metal alloy nanoparticles copper, indium and/or gallium made preferably from a vapor condensation process or other suitable process, the layer also including elemental selenium and/or sulfur heated at temperatures sufficient to permit reaction between the nanoparticles and the selenium and/or sulfur to form a substantially fused layer. The reaction may result in the formation of a chalcopyrite material. The layer has been shown to be an efficient solar energy absorber for use in photovoltaic cells.
1 . A photovoltaic cell comprising:
a photon-absorbing layer comprising metal alloy nanoparticles substantially fused together, the nanoparticles comprising the formula Cu 1 In 1-x Ga x , where x ranges from 0 to 1, said layer having been prepared by heating the nanoparticles sufficiently to permit reaction with material comprising either selenium and/or sulfur;
an electrically conductive substrate supporting the photon-absorbing layer and providing at least a portion of an electrical circuit in combination with said photon-absorbing layer;
an emitting layer comprising material capable of absorbing electrons from the photon-absorbing layer; and
an anti-reflective coating comprising material suitable for permitting a significant amount of sunlight that strikes the cell to reach the photon-absorbing layer.
2 . The photovoltaic cell of claim 1 , further comprising an environmental protection layer to reduce environmental degradation of the cell during use.
3 . The photovoltaic cell of claim 1 , wherein the layer is less than about 1 micron.
4 . The photovoltaic cell of claim 1 , wherein the layer is less than about 500 nanometers.
5 . The photovoltaic cell of claim 1 wherein the anti-reflective coating comprises zinc oxide.
6 . The photovoltaic cell of claim 1 , wherein the emitting layer comprises cadmium sulfide.
7 . The photovoltaic cell of claim 2 , wherein the environmental protection layer further comprises glass having a low iron content.
8 . The photovoltaic cell of claim 1 , wherein a substantial portion of the nanoparticles are less than about 50 nanometers.
9 . The photovoltaic cell of claim 1 , wherein the photon-absorbing layer comprises nanoparticles created using a vapor condensation process.
10 . A method of preparing an electronic device, the method comprising:
mixing on an electrically conductive substrate particles comprising at least one element selected from Groups VA and/or VIA with metal alloy nanoparticles made from a vapor condensation process; and
heating the mixture to at least a reaction temperature that is sufficient to create a substantially fused layer of nanosized particles.
11 . The method of claim 10 , wherein the resulting layer comprises chalcopyrite.
12 . The method of claim 10 , wherein a substantial portion of the metal alloy nanoparticles are less than 50 nm.
13 . The method of claim 10 , wherein the resulting layer is suitable for use in a photovoltaic cell.
14 . The method of claim 10 , wherein the heating step comprises heating the mixture to a temperature of at least 250° C.
15 . The method of claim 10 , wherein the resulting layer is less than about 1 micron.
16 . The method of claim 10 , wherein the resulting layer is less than about 500 nanometers.
17 . The method of claim 10 , wherein the resulting layer is less than about 500 nanometers on average.
18 . A composition having photon-absorbing characteristics, the composition comprising metal alloy nanoparticles made from a vapor condensation process, the composition suitable for use in an electronic device.
19 . The composition of claim 18 , wherein the metal alloy nanoparticles are comprised of at least one metal from group IB, IIB, or IIIA.
20 . The composition of claim 19 , wherein the metal alloy nanoparticles comprises at least one of copper, indium, or gallium.
21 . The composition of claim 18 , wherein a substantial portion of the metal alloy nanoparticles is less than 50 nm.
22 . The composition of claim 18 , wherein at least some of the metal alloy nanoparticles have an oxide shell.
23 . The composition of claim 18 , wherein the metal alloy nanoparticles have sufficiently high reactivity to permit reaction with material from either Group VA and/or VIA in the gas, liquid, or solid state.
24 . The composition of claim 23 , wherein the material comprises either elemental selenium and/or sulfur.
25 . A photovoltaic cell comprising:
a photon-absorbing layer comprising copper-indium alloy nanoparticles substantially fused together, said layer prepared by heating the nanoparticles sufficiently to permit reaction with material comprising either Group VA and/or VIA;
an electrically conductive substrate supporting the photon-absorbing layer and providing at least a portion of an electrical circuit in combination with said layer;
an emitting layer comprising material capable of absorbing electrons from the photon-absorbing layer; and
an anti-reflective coating comprising material suitable for permitting a significant amount of sunlight that strikes the cell to reach the photon-absorbing layer.
26 . The photovoltaic cell of claim 25 , wherein the photon-absorbing layer is less than about 0.5 microns thick.
27 . The photovoltaic cell of claim 25 , further comprising an environmental protection layer to reduce environmental degradation of the cell during use.
28 . The photovoltaic cell of claim 25 wherein the Group. VA and/or VIA material comprises either selenium and/or sulfur.
29 . The photovoltaic cell of claim 25 wherein the photon-absorbing layer further comprises gallium.
30 . The photovoltaic cell of claim 25 wherein the anti-reflective coating comprises zinc oxide.
31 . The photovoltaic cell of claim 25 wherein the emitting layer comprises cadmium sulfide.
32 . The photovoltaic cell of claim 25 wherein the environmental protection layer further comprises glass having a low iron content.
33 . A stratified layer of metal alloy nanoparticles comprising the formula Cu 1 In 1-x Ga x .
34 . The layer of claim 33 , wherein the gallium concentration in at least one of the stratifications is different from the gallium concentration in another stratification.
35 . The composition of claim 33 , wherein x ranges from 0 to 1.
36 . The composition of claim 33 , wherein the concentration of gallium is lower proximal to the emitting layer.
37 . The composition of claim 33 , wherein there are a minimum of three stratifications and a maximum of twenty stratifications.
38 . The layer of claim 33 , wherein the thickness is less than about 1 micron.
39 . The layer of claim 33 , wherein the average thickness is less than about 500 nanometers.