High-throughput printing of chalcogen layer and the use of an inter-metallic material
Methods and devices for high-throughput printing of a precursor material for forming a film of a group IB-IIIA-chalcogenide compound are disclosed. In one embodiment, the method comprises forming a precursor layer on a substrate, wherein the precursor layer comprises one or more discrete layers. The layers may include at least a first layer containing one or more group IB elements and two or more different group IIIA elements and at least a second layer containing elemental chalcogen particles. The precursor layer may be heated to a temperature sufficient to melt the chalcogen particles and to react the chalcogen particles with the one or more group IB elements and group IIIA elements in the precursor layer to form a film of a group IB-IIIA-chalcogenide compound. At least one set of the particles in the precursor layer are inter-metallic particles containing at least one group IB-IIIA inter-metallic alloy phase. The method may also include making a film of group IB-IIIA-chalcogenide compound that includes mixing the nanoparticles and/or nanoglobules and/or nanodroplets to form an ink, depositing the ink on a substrate, heating to melt the extra chalcogen and to react the chalcogen with the group IB and group IIIA elements and/or chalcogenides to form a dense film.
1 . A method comprising:
forming a precursor layer on a substrate, wherein the precursor layer comprises one or more discrete layers comprising:
a) at least a first layer containing one or more group IB elements and two or more different group IIIA elements;
b) at least a second layer containing elemental chalcogen particles; and
heating the precursor layer to a temperature sufficient to melt the chalcogen particles and to react the chalcogen particles with the one or more group IB elements and group IIIA elements in the precursor layer to form a film of a group IB-IIIA-chalcogenide compound;
wherein at least one set of the particles in the precursor layer are inter-metallic particles containing at least one group IB-IIIA inter-metallic alloy phase.
2 . The method of claim 1 wherein the first layer is formed over the second layer.
3 . The method of claim 1 wherein the second layer is formed over the first layer.
4 . The method of claim 1 wherein the first layer also contains elemental chalcogen particles.
5 . The method of claim 1 wherein the first layer group IB elements in the form of a group IB-chalcogenide.
6 . The method of claim 1 wherein the first layer group IIIA elements in the form of a group IIIA-chalcogenide.
7 . The method of claim 1 further comprising a third layer containing elemental chalcogen particles.
8 . The method of claim 1 wherein the two or more different group IIIA elements include indium and gallium.
9 . The method of claim 1 wherein the group IB element is copper.
10 . The method of claim 1 , wherein chalcogen particles are particles of selenium, sulfur or tellurium.
11 . The method of claim 1 wherein the precursor layer is substantially oxygen-free.
12 . The method of claim 1 wherein forming the precursor layer includes forming a dispersion including nanoparticles containing one or more group IB elements and nanoparticles containing two or more group IIIA elements, spreading a film of the dispersion onto the substrate.
13 . The method of claim 1 wherein forming the precursor layer includes sintering the film to form the precursor layer.
14 . The method of claim 1 herein sintering the precursor layer takes place before the step of disposing the layer containing elemental chalcogen particles over the precursor layer.
15 . The method of claim 1 wherein the substrate is a flexible substrate and wherein forming the precursor layer and/or disposing the layer containing elemental chalcogen particles over the precursor layer, and/or heating the precursor layer and chalcogen particles includes the use of roll-to-roll manufacturing on the flexible substrate.
16 . The method of claim 1 wherein the substrate is an aluminum foil substrate.
17 . The method of claim 1 wherein the group IB-IIIA-chalcogenide compound is of the form Cu z In (1-x) Ga x S 2(1-y) Se 2y , where 0.5≦z≦1.5, 0≦x≦1.0 and 0≦y≦1.0.
18 . The method of claim 1 , wherein heating of precursor layer and chalcogen particles includes heating the substrate and precursor layer from an ambient temperature to a plateau temperature range of between about 200° C. and about 600° C., maintaining a temperature of the substrate and precursor layer in the plateau range for a period of time ranging between about a fraction of a second to about 60 minutes, and subsequently reducing the temperature of the substrate and precursor layer.
19 . The method of claim 1 wherein the film includes a group IB-IIIA-VIA compound.
20 . The method of claim 1 wherein reacting comprises heating the layer in the suitable atmosphere.
21 . The process of claim 1 wherein at least one set of the particles in the dispersion is in the form of nanoglobules.
22 . The method of claim 1 wherein at least one set of the particles in the dispersion are in the form of nanoglobules and contain at least one group IIIA element.
23 . The method of claim 1 wherein at least one set of the particles in the dispersion is in the form of nanoglobules comprising of a group IIIA element in elemental form.
24 . The method of claim 1 wherein the inter-metallic phase is not a terminal solid solution phase.
25 . The method of claim 1 wherein the inter-metallic phase is not a solid solution phase.
26 . The method of claim 1 wherein inter-metallic particles contribute less than about 50 molar percent of group IB elements found in all of the particles.
27 . The method of claim 1 wherein inter-metallic particles contribute less than about 50 molar percent of group IIIA elements found in all of the particles.
28 . The process of claim 1 wherein inter-metallic particles contribute less than about 50 molar percent of the group IB elements and less than about 50 molar percent of the group IIIA elements in the dispersion deposited on the substrate.
29 . The method of claim 1 wherein inter-metallic particles contribute less than about 50 molar percent of the group IB elements and more than about 50 molar percent of the group IIIA elements in the dispersion deposited on the substrate.
30 . The process of claim 1 wherein inter-metallic particles contribute more than about 50 molar percent of the group IB elements and less than about 50 molar percent of the group IIIA elements in the dispersion deposited on the substrate.
31 . The process of claim 10 wherein the molar percent is based on a total molar mass of the elements in all particles present in the dispersion.
32 . The process of claim 1 wherein at least some of the particles have a platelet shape.
33 . The process of claim 1 wherein a majority of the particles have a platelet shape.
34 . The process of claim 1 wherein all of the particles have a platelet shape.
35 . The method of claim 1 wherein the depositing step comprises coating the substrate with the dispersion.
36 . The process of claim 1 wherein the dispersion comprises an emulsion.
37 . The method of claim 1 wherein the inter-metallic material is a binary material.
38 . The method of claim 1 wherein the inter-metallic material is a ternary material.
39 . The process of claim 1 wherein the inter-metallic material comprises Cu 1 In 2 .
40 . The method of claim 1 wherein the inter-metallic material comprises a composition in a δ phase of Cu 1 In 2 .
41 . The method of claim 1 wherein the inter-metallic material comprises a composition in between a δ phase of Cu 1 In 2 and a phase defined by Cu 16 In 9 .
42 . The method of claim 1 wherein the inter-metallic material comprises Cu 1 Ga 2 .
43 . The method of claim 1 wherein the inter-metallic material comprises an intermediate solid-solution of Cu 1 Ga 2 .
44 . The method of claim 1 wherein the inter-metallic material comprises Cu 68 Ga 38 .
45 . The method of claim 1 wherein the inter-metallic material comprises Cu 70 Ga 30 .
46 . The method of claim 1 wherein the inter-metallic material comprises Cu 75 Ga 25 .
47 . The method of claim 1 wherein the inter-metallic material comprises a composition of Cu—Ga of a phase in between the terminal solid-solution and an intermediate solid-solution next to it.
48 . The method of claim 1 wherein the inter-metallic comprises a composition of Cu—Ga in a γ 1 phase (about 31.8 to about 39.8 wt % Ga).
49 . The method of claim 1 wherein the inter-metallic comprises a composition of Cu—Ga in a γ 2 phase (about 36.0 to about 39.9 wt % Ga).
50 . The method of claim 1 wherein the inter-metallic comprises a composition of Cu—Ga in a γ 3 phase (about 39.7 to about −44.9 wt % Ga).
51 . The method of claim 1 wherein the inter-metallic comprises a composition of Cu—Ga in a θ phase (about 66.7 to about 68.7 wt % Ga).
52 . The method of claim 1 wherein the inter-metallic comprises a composition of Cu—Ga in a phase between γ 2 and γ 3 .
53 . The method of claim 1 wherein the inter-metallic comprises a composition of Cu—Ga in a phase between the terminal solid solution and γ 1 .
54 . The method of claim 1 wherein the inter-metallic material comprises Cu-rich Cu—Ga.
55 . The method of claim 1 wherein gallium is incorporated as a group IIIA element in the form of a suspension of nanoglobules.
56 . The process of claim 55 wherein nanoglobules of gallium are formed by creating an emulsion of liquid gallium in a solution.
57 . The process of claim 55 wherein gallium is quenched below room temperature.
58 . The process of claim 55 further comprising maintaining or enhancing a dispersion of liquid gallium in solution by stirring, mechanical means, electromagnetic means, ultrasonic means, and/or the addition of dispersants and/or emulsifiers.
59 . The method of claim 1 further comprising adding a mixture of one or more elemental particles selected from: aluminum, tellurium, or sulfur.
60 . The method of claim 1 wherein the suitable atmosphere contains at least one of the following: selenium, sulfur, tellurium, H 2 , CO, H 2 Se, H 2 S, Ar, N 2 or combinations or mixture thereof.
61 . The method of claim 1 wherein the suitable atmosphere contains at least one of the following: H 2 , CO, Ar, and N 2 .
62 . The method of claim 1 wherein one or more classes of the particles are doped with one or more inorganic materials.
63 . The method of claim 1 , wherein one or more classes of the particles are doped with one or more inorganic materials chosen from the group of aluminum (Al), sulfur (S), sodium (Na), potassium (K), or lithium (Li).
64 . The process of claim 1 wherein the particles are nanoparticles.
65 . The process of claim 1 further comprising forming the particles from a feedstock having an inter-metallic phase.
66 . The method of claim 1 further comprising forming the particles from a feedstock having an inter-metallic phase and nanoparticles are formed by one of the following processes: milling, electroexplosive wire (EEW) processing, evaporation condensation (EC), pulsed plasma processing, or combinations thereof.
67 . A method for forming a film of a group IB-IIIA-chalcogenide compound, the method comprising:
forming a precursor layer on a substrate, the precursor layer containing one or more group IB elements and one or more group IIIA elements;
sintering the precursor layer;
after sintering the precursor layer, forming a layer containing elemental chalcogen particles over the precursor layer; and
heating the precursor layer and chalcogen particles to a temperature sufficient to melt the chalcogen particles and to react the chalcogen particles with the group IB element and group IIIA elements in the precursor layer to form a film of a group IB-IIIA-chalcogenide compound;
wherein at least one set of the particles in the precursor layer are inter-metallic particles containing at least one group IB-IIIA inter-metallic alloy phase.
68 . The method of claim 67 wherein the substrate is an aluminum foil substrate.
69 . A method comprising:
forming a precursor layer containing particles having one or more group IB elements and two or more different group IIIA elements;
forming a layer containing surplus chalcogen particles providing a source of excess chalcogen, wherein the precursor layer and the surplus chalcogen layer are adjacent to one another; and
heating the precursor layer and the surplus chalcogen layer to a temperature sufficient to melt the particles providing the source of excess chalcogen and to react the particles with the one or more group IB elements and group IIIA elements in the precursor layer to form a film of a group IB-IIIA-chalcogenide compound on a substrate;
wherein at least one set of the particles in the precursor layer are inter-metallic particles containing at least one group IB-IIIA inter-metallic alloy phase.