SOLAR CELL ABSORBER LAYER FORMED FROM METAL ION PRECURSORS
Methods and devices are provided for forming an absorber layer. In one embodiment, a method is provided comprising of depositing a solution on a substrate to form a precursor layer. The solution comprises of at least one polar solvent, at least one binder, and at least one Group IB and/or IIIA hydroxide. The precursor layer is processed in one or more steps to form a photovoltaic absorber layer. In one embodiment, the absorber layer may be created by processing the precursor layer into a solid film and then thermally reacting the solid film in an atmosphere containing at least an element of Group VIA of the Periodic Table to form the photovoltaic absorber layer. Optionally, the absorber layer may be processed by thermal reaction of the precursor layer in an atmosphere containing at least an element of Group VIA of the Periodic Table to form the photovoltaic absorber layer.
1 . A method comprising:
depositing a solution on a substrate to form a precursor layer, the solution comprising:
at least one Group IB and/or IIIA hydroxide;
processing the precursor layer in one or more steps to form a photovoltaic absorber layer.
2 . A method comprising:
depositing a solution on a substrate to form a precursor layer, the solution comprising:
at least one polar solvent;
at least one binder; and
at least one Group IB and/or IIIA hydroxide;
processing the precursor layer in one or more steps to form a photovoltaic absorber layer.
3 . The method of claim 2 further comprising creating the absorber layer by processing the precursor layer into a solid film and then thermally reacting the solid film in an atmosphere containing at least an element of Group VIA of the Periodic Table to form the photovoltaic absorber layer.
4 . The method of claim 2 further comprising creating the absorber layer by thermal reaction of the precursor layer in an atmosphere containing at least an element of Group VIA of the Periodic Table to form the photovoltaic absorber layer.
5 . The method of claim 2 wherein Group IB and/or IIIA hydroxide comprises indium hydroxide.
6 . The method of claim 2 wherein Group IB and/or IIIA hydroxide comprises gallium hydroxide.
7 . The method of claim 2 wherein Group IB and/or IIIA hydroxide comprises indium-gallium hydroxide.
8 . The method of claim 2 wherein the precursor layer comprises of Cu—Ga, indium hydroxide, and elemental gallium.
9 . The method of claim 2 wherein the precursor layer comprises of Cu 85 Ga 15 , In(OH) 3 , and elemental gallium.
10 . The method of claim 2 wherein the precursor layer further comprises of copper nanoparticles and indium-gallium hydroxide.
11 . The method of claim 2 wherein the precursor layer further comprises copper-gallium and indium hydroxide without separate elemental gallium.
12 . The method of claim 2 wherein the binder is an organic binder
13 . The method of claim 2 wherein the binder is selected from the group consisting of: substituted celluloses, celluloses, the polyvinyl alcohols, polyethylenoxides, the polyacrylonitriles, polysaccharides, nitrocelluloses, polyvinylpyrrolidone, or combinations thereof.
14 . The method of claim 1 wherein the polar solvent is an organic solvent.
15 . The method of claim 1 wherein the polar solvent is selected from the group consisting of: aliphatic alcohols, the polyglycols, polyethers, polyols, esters, ethers, ketones, nitriles, alkoxyalcohols, iso-propyl alcohol, or combinations thereof.
16 . The method of claim 1 wherein processing comprises annealing with a ramp-rate of 1-5 C/sec, preferably over 5 C/sec, to a temperature of about 225 to 550° C.
17 . The method of claim 1 wherein processing comprises annealing with a ramp-rate of 1-5 C/sec, preferably over 5 C/sec, to a temperature of about 225 to 550° C. preferably for about 30 seconds to about 600 seconds to enhance conversion of indium hydroxide, densification and/or alloying between Cu, In, and Ga in an atmosphere containing hydrogen gas, where the plateau temperature not necessarily is kept constant in time.
18 . The method of claim 1 wherein processing further comprise selenizing this annealed layer with a ramp-rate of over 5 C/sec, to a temperature of about 225 to 575 C for a time period of about 60 seconds to about 10 minutes in Se vapor in a non-vacuum atmosphere, where the plateau temperature not necessarily is kept constant in time, to form the thin-film containing one or more chalcogenide compounds containing Cu, In, Ga, and Se.
19 . The method of claim 1 wherein processing comprise selenizing without the separate annealing step in an atmosphere containing hydrogen gas, but may be densified and selenized in one step with a ramp-rate of over 5 C/sec, to a temperature of 225 to 575 C for a time period of about 120 seconds to about 20 minutes in an atmosphere containing either H2Se or a mixture of H2 and Se vapor in a non-vacuum pressure.