US20100213073A1

US20100213073A1 - Bath for electroplating a i-iii-vi compound, use thereof and structures containing same

Info

Publication number: US20100213073A1
Application number: US12/390,877
Authority: US
Inventors: Qiang Huang; Xiaoyan Shao; Andrew J. Kellock
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 2009-02-23
Filing date: 2009-02-23
Publication date: 2010-08-26

Abstract

A bath for electroplating a I-III-VI compound comprising: water; a copper containing precursor dissolved in said water; a selenium containing precursor dissolved in said water; and at least one member selected from the group consisting of an indium containing precursor dissolved in said water, a gallium containing precursor dissolved in said water and mixtures thereof, and at least one member selected from the group consisting of sulfur-containing organic compound dissolved in said water wherein one or more sulfur atoms directly bond with at least one carbon atom, a phosphorus-containing organic compound dissolved in said water wherein one or more phosphorus atoms directly bond with at least one carbon atom and mixtures thereof is provided along with its use to fabricate thin films, solar devices and tuned thin films.

Description

TECHNICAL FIELD

The present disclosure relates to baths for electroplating I-III-VI compounds employing certain sulfur-containing organic compounds and/or certain phosphorous-containing organic compounds and use of the baths for producing films of I-III-VI compounds. The present disclosure also relates a method for producing films of I-III-VI wherein the film has a composition gradient of gallium and/or indium. Moreover, the present disclosure relates to producing solar cells containing the films of I-III-VI compounds.

BACKGROUND OF THE DISCLOSURE

A solar cell is a device that converts light energy into electrical energy. Ternary compounds are of considerable interest as the absorber layer for solar devices. Cu(In_xGa_1-x)Se₂(CIGS), a I-III-VI₂semiconductor compound, is one of the most promising materials for solar applications.
Electrodeposition of Cu(In_xGa_1-x)Se₂(CIGS) is a relatively cheap method of producing large scale semiconductor material for thin film solar cells. In order to have the right material property for solar cell applications, the composition of the films is critical, especially the In and/or Ga content. For example, the stoichiometry of some of the most desired films can be written as Cu(In_xGa_1-x)Se_ywith x=0.5 to 1, and y close to 2. The corresponding atomic composition is 0 to 12.5% for Ga, and 12.5% to 25% for In.
One of the main challenges of the electroplating method to form CIGS films so far is how to achieve the incorporation of Ga and In, especially Ga, into the other elements. The reason for this difficulty is Ga and In are much less noble than Cu and Se. This difference is even more severe for Ga. In other words, the electrochemical reversible potential for Ga is more negative than In, and much more negative than Cu and Se. This difference in the reversible potential prohibits the co-deposition of Ga with the other elements. Another reason for the difficulty for the co-deposition of Ga is due to the presence of water and a very high hydrogen evolution rate on Ga surface. Because a highly negative potential is needed to deposit Ga due to its negative reversible potential, water decomposes very easily on a Ga surface. This results in a violent hydrogen evolution and a locally high pH, and prevents the deposition of compounds film.
US patent application US2006/0151331A1, suggested a method of using a CH3-(CH2)n-CH2-OSO3-X type of surfactant to increase the Ga content in the electrodeposited film. However, use of the disclosed surfactant at the recommended concentrations, the solution obtained is cloudy in appearance and suffers a serious foaming problem, which prohibits its practical application.

SUMMARY

The present disclosure makes it possible to improve the solution properties and stability for the deposition of Group I-III-VI films. In addition, the present disclosure provides a method that allows a better control of the film quality and composition. In particular, an aspect of the present disclosure relates to a bath for electroplating a I-III-VI compound that comprises water; a copper containing precursor dissolved in the water; a selenium containing precursor dissolved in the water; one or both of an indium containing precursor dissolved in the water and a gallium containing precursor dissolved in the water; and one or both of a sulfur-containing organic compound dissolved in the water wherein one or more sulfur atoms directly bond with at least one carbon atom of the compound, and a phosphorus-containing organic compound dissolved in the water wherein one or more phosphorus atoms directly bond with at least one carbon atom of the compound.
Another aspect of this disclosure relates to a method of producing a I-III-VI compound in a thin film form by electroplating which comprises obtaining an aqueous plating bath disclosed above, providing a cathode and an anode in the plating bath; and applying an electric current or potential across the cathode and anode to deposit a film of the I-III-VI compounds on the cathode. Typical thin film thicknesses are about 20 nanometers to about 20 microns and more typically about 100 nanometers to about 5 microns.
A still further aspect of the present disclosure is concerned with a method of producing a film of a Group I-III-VI compound by electroplating, wherein the film has a composition gradient of gallium from 0 atomic % to 60 atomic % or a composition gradient of indium from 0 atomic % to 90 atomic % or both, which comprises obtaining an aqueous plating bath disclosed above, providing a cathode and an anode in the plating bath; and applying a electric current or potential across the cathode and anode to deposit a film of the I-III-VI compounds on the cathode. The gradient is achieved by controlling and varying the plating conditions, including current/potential, temperature, and/or rotation conditions. The gradient can also be achieved by repeating the electroplating processes by two or more times in two or more different baths.
Another aspect of the present invention relates to a method for fabricating a solar device which comprises obtaining an aqueous plating bath disclosed above, providing a cathode an anode in the plating bath, wherein the cathode comprises a substrate for a solar device applying an electric current or potential across the cathode and anode to deposit a film of the I-III-VI compounds on the cathode, and providing contact layers on one or both sides of the I-III-VI compounds.
Still other objects and advantages of the present disclosure will become readily apparent by those skilled in the art from the following detailed description, wherein it is shown and described preferred embodiments, simply by way of illustration of the best mode contemplated. As will be realized the disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the disclosure. Accordingly, the description is to be regarded as illustrative in nature and not as restrictive.

SUMMARY OF DRAWINGS

FIG. 1 a-1 d show structures of exemplary sulfur-containing compounds and phosphorus-containing compounds.
FIG. 2 a-2 d show the electron dispersive x-ray analysis for the compositions of the electroplated films.
FIG. 3 a-3 d show the scanning electron microscopy images of the electroplated films.
FIG. 4 shows the compositions of the electroplated films analyzed by photon induced x-ray emission (PIXE).
FIG. 5 shows the compositions of the electroplated films analyzed by photon induced x-ray emission (PIXE).
FIG. 6 a-6 b show the compositions of the electroplated films analyzed by photon induced x-ray emission (PIXE).

BEST AND VARIOUS MODES

The electroplating baths according to the present disclosure comprise water; a copper containing precursor dissolved in the water; a selenium containing precursor dissolved in the water; one or both of an indium containing precursor dissolved in the water and a gallium containing precursor dissolved in the water; and one or both of a sulfur-containing organic compound dissolved in the water wherein one or more sulfur atoms directly bond with at least one carbon atom of the compound, and a phosphorus-containing organic compound dissolved in the water wherein one or more phosphorus atoms directly bond with at least one carbon atom of the compound.
The copper precursor can be any copper salt that can be dissolved in water, and typically is copper sulfate, copper perchlorate and copper nitrate. The concentration of copper is typically about 0. 1 mmol/L—about 1 mol/L, and more typically about 0.1 mmol/L—about 20 mmol/L, and even more typically about 1 mmol/L—about 10 mmol/L.
The selenium precursor can be any selenium salt that can be dissolved in water, including selenium oxide, selenium nitrate, selenium perchlorate and selenium sulfate. The concentration of selenium is typically about 0.1 mmol/L—about 1 mol/L, and more typically about 0.1 mmol/L—about 100 mmol/L, and even more typically about 1 mmol/L—about 10 mmol/L.
The indium precursor, when present, can be any indium salt that can be dissolved in water, including indium sulfate, indium chloride, indium perchlorate and indium nitrate. The concentration of indium is typically about 0.1 mmol/L—about 1 mol/L, and more typically about 0.1 mmol/L—about 100 mmol/L, and even more typically about 1 mmol/L—about 10 mmol/L.
The gallium precursor, when present, can be any gallium salt that can be dissolved in water, including gallium sulfate, gallium perchlorate and gallium nitrate. The concentration of gallium is typically about 0. 1 mmol/L—about 2 mol/L, and more typically about 1 mmol/L—about 200 mmol/L, and even more typically 10 mmol/L—200 mmol/L.
In addition to the above precursors, the bath of the present disclosure can other metal precursors for incorporating into the films such as Ag, Zn, Cd, Te, S, Sb, Ge, Sn, As and mixtures thereof The present disclosure is especially concerned with obtaining films of copper indium selenide, copper gallium selenide, and preferably copper indium gallium selenide compounds.
As mentioned above, the sulfur-containing organic compound includes one or more sulfur atoms directly bond with at least one carbon atom of the compound. Examples of particular sulfur-containing compounds are sulfonic acid and sulfonate (R—SO₂—OX), sulfinic acid and sulfinate (R—SO—OX), sulfonide (R—SO₂—R′), sulfinide (R—SO—R′), sulfide (R—S—X) or disulfide (R—S—S—R′), where R and R′ stand for organic chain structures or aromatic ring structures; and X stands for a positive charged ion such as H, Na, K, R and R′ can be saturated or unsaturated, branched or unbranched, and may contain hetero atoms such as S, O or N. The organic chains typically contain from 1 to about 30 carbon atoms, and more typically from 1 to about 15 carbon atoms. One or more carbon atoms can be substituted by other elements including N and S. Examples of some alkyl chain structures are CH₃—CH₂—CH₂—CH₂—; (CH₃—CH₂)₂—CH—CH₂—; NH₂—. The aromatic ring structures typically contain 5-14 carbon atoms in the ring(s) and more typically 6 to 10 carbon atoms in the ring(s). The aromatic rings can be substitutes such as with one or more alkyl groups. Examples of some aromatic rings are benzene, propylnaphthalene and benzimidazole. The sulfur atom in the sulfur-containing compound can be on the aromatic ring as a substitute for carbon atom as well, such as the case of thiophene. The sulfur containing compound can be for example a sulfonate, sulfonic acid, sulfinic acid, sulfinate, sulfonide, sulfinide, sulfide, disulfide and is preferably a sulfonate, sulfinate, sulfonide and sulfinide. Examples of some specific sulfur containing compounds are sodium diisopropylnaphthalene sulfonate and benzene sulfinic acid, saccharin and thiourea.
As mentioned above, the phosphorus-containing organic compound includes one or more phosphorus atoms directly bond with at least one carbon atom of the compound. The phosphorus-containing compounds include phosphonic acid and phosphonate (R—PO(—OR′)—OX), phosphinic acid and phosphinate (R—PO(—R′)—OX), phosphonite (R—P(—OR′)—OX) and phosphinite (R—P(—R′)—OX), where R stands for organic chain structures or aromatic ring structures; X and Y stand for positive charged ions such as H, Na, and K; and R′ stands for organic chain structures, organic aromatic ring structures. R and R′ can be saturated or unsaturated, branched or unbranched, and may contain hetero atoms such as S, O or N. The organic chains typically contain 1 to about 30 carbon atoms, and more typically from 1 to about 15 carbon atoms. One or more carbon atoms can be substituted by other elements including N and S. Examples of some alkyl chain structures are CH₃—CH₂—CH₂—CH₂—; (CH₃—CH₂)₂—CH—CH₂—; NH₂—. The aromatic ring structures typically contain 5-14 carbon atoms in the ring(s) and more typically 6 to 10 carbon atoms in the ring(s). The aromatic rings can be substitutes such as with one or more alkyl groups. Examples of some aromatic rings are benzene, propylnaphthalene and benzimidazole. The phosphorus-containing compound can be for example a phosphonate, phosphonic acid, phosphinate, phosphinic acid, phosphonite and phosphinite and is preferably a phosphonate or phosphinate.
FIG. 1 shows structures of exemplary sulfur-containing compounds and phosphorus-containing compounds. Among them, FIG. 1( c) shows exemplary ring structures that can be present in the sulfur-containing compounds and phosphorous-containing compounds. FIG. (d) shows the structures of four examples of sulfur-containing compounds, sodium diisopropylnaphthalene sulfonate, benzene sulfinic acid, thiourea, and saccharin.
The concentration of the sulfur-containing compounds such as the sulfonate and sulfinate or the phosphorus-containing compounds such as the phosphonate and phosphinate is typically about 0.1 mmol/L—about 2 mol/L, and more typically about 1 mmol/L—about 500 mmol/L, and even more typically about 5 mmol/L—about 200 mmol/L.
The sulfur- and/or phosphorus-containing compounds improve the uniformity and continuity of the film, increase the deposition rate of the film, and increase the content of the indium and/or gallium.
The plating solution may also contain one or more other inorganic chemicals, such as sodium sulfate, potassium nitrate, to provide enhanced conductivity of the solution to carry the current for electroplating.
The solution may also optionally contain other organic compounds including additional surfactants. These additional surfactants can be sulfur-containing or not sulfur-containing, phosphorus-containing or not phosphorus-containing.
The solution may also contain other organic or inorganic compounds such as organic acids (R—COOH) and ammonium salts to provide complexing function for the precursor chemicals. If desired, the solution may contain one or more other chemicals to provide buffer for the pH of the solution. Moreover, if desired, the solution may contain one or more solvents other than water, including alcohol, glycol, and glycerol. Also, the solution may contain one or more other organic or inorganic chemicals to incorporate other elements into the electroplated film, including C, B, N, O, S, H, Cl, Ag, Au, Cd, Zn, Al, Te, Ge, Sn and As.
The electroplating was carried out by immersing a conductive substrate in to a solution containing the precursor chemicals, including copper and selenide and indium and/or gallium, and; and applying electric power across the substrate and an anode in the same solution. The anode is typically made of metal such as Pt, Au, Ti or other conductive material such as graphite. The substrate used for plating can be metal or other conductive material, but is preferably a layer of Mo (molybdenum) deposited on another substrate including Si, SiO₂and steel.
The plating can be carried out with or without agitation. The plating is typically carried out at temperatures of about 5° C.—about 80° C., and more typically about 20° C.-50° C.
The plating is typically carried out at a DC current density from about −1 mA/cm²to about −100 mA/cm², and more typically about −3 mA/cm²to about −50 mA/cm², and even more typically about −5 mA/cm²to about −30 mA/cm².
The plating can be carried out at a current waveform, such as sweep, pulse, pulse reverse, sinusoidal waveforms. A waveform may be necessary to create a compositional gradient in the I-III-VI film, which is desired for the solar energy applications.
In addition, the compound can be annealed at a temperature higher than 20° C. to about 800° C., typically about 30° C. to about 400° C. and more typically about 50 ° C. to about 250° C., after electroplating, typically for about 1 minute to about 600 minutes and more typically for about 1 minute to about 120 minutes. The annealing can be carried out in vacuum or in N2, He, forming gas, H2S, H2Se and any gas at the temperature of annealing. The annealing makes it possible to further adjust the composition of the I-III-VI compounds, to adjust the distribution of composition of the compounds, to modify the grain structure of the compounds, to activate the material and to improve device performance.
In addition, the compound thin film can be further used as the substrate upon one side or both sides of which are provided contact materials to be made into solar devices.
The following non-limiting examples are presented to further illustrate the present disclosure and are not intended to limit the disclosure.

EXAMPLE 1

The solution employed in this example contains 2.25 mmol/L CuSO₄, 1.25 mmol/L In₂(SO₄)₃, 3.75 mmol/L SeO₂, 100 mmol/L Ga(NO₃)₃, 0.2 mol/L Na₂SO₄, pH=2. The solution contains 0 or 0.2 mol/L sodium diisopropylnaphthalene sulfonate (SDIPNS).
FIG. 2 shows the electron dispersive x-ray analysis for the compositions of the electroplated films. The peak height of each element stands for the amount of the element in the film.
FIG. 3 shows the scanning electron microscopy images of the electroplated films.


	−15 mA/cm2,	−20 mA/cm2,
	plated for 2 min	plated for 2 min

No SDIPNS	FIG. 2(a), FIG. 3(a)	FIG. 2(b), FIG. 3(b)
0.2 mol/L SDIPNS	FIG. 2(c), FIG. 3(c)	FIG. 2(d), FIG. 3(d)

As the peak height of each element stands for the amount of the element in the film, it is evident that the presence of the sulfonate compound in the solution significantly increased the amount of the gallium and indium in the electrodeposited film.
The scanning electron microscopy images showed the presence of the sulfonate compounds in the solution significantly improved the continuity and uniformity of the electrodeposited film.

EXAMPLE 2

In this example, a first solution contains 1.13 mmol/L CuSO₄, 0.63 mmol/L In₂(SO₄)₃, 1.88 mmol/L SeO₂, 25 mmol/L Ga(NO₃)₃, 0.2 mol/L Na_SO ₄, 0.2 mol/L SDIPNS, pH=2.
In addition, a second solution contains 4.5 mmol/L CuSO₄, 2.5 mmol/L In₂(SO₄)₃, 7.5 mmol/L SeO₂, 25 mmol/L Ga(NO₃)₃, 0.2 mol/L Na₂SO₄, 0.2 mol/L SDIPNS, pH=2.
The plating was carried out at room temperature and at current density from −10 mA/cm²to −20 mA/cm², for 2 minutes.
FIG. 4 shows the compositions of the electroplated films analyzed by photon induced x-ray emission (PIXE). The dashed line shows the composition of the film plated from the first solution, and the solid line shows the composition of the film plated from the first solution.
The gallium content can be controlled from 0 to 10.4% and the indium content can be controlled from 10% to 25.7%.

EXAMPLE 3

In this example, a first solution contains 2.25 mmol/L CuSO₄, 1.25 mmol/L In₂(SO₄)₃, 3.75 mmol/L SeO₂, 100 mmol/L Ga(NO₃)₃, 0.2 mol/L Na₄, 0.2 mol/L SDIPNS, pH=2.
In addition, a second solution contains 2.25 mmol/L CuSO₄, 1.25 mmol/L In₂(SO₄)₃, 3.75 mmol/L SeO₂, 25 mmol/L Ga(NO₃)₃, 0.2 mol/L Na₂SO₄, 0.2 mol/L SDIPNS, pH=2.
The plating was carried out at room temperature and at current density from −10 mA/cm²to −20 mA/cm², for 2 minutes.
FIG. 5 shows the compositions of the electroplated films analyzed by photon induced x-ray emission (PIXE). The dashed line shows the composition of the film plated from the first solution, and solid line shows the composition of the film plated from the first solution.
The gallium content can be controlled from 1.4 to 32.9% and the indium content can be controlled from 12.8% to 26.7%.

EXAMPLE 4

In this example the solution contains 2.25 mmol/L CuSO₄, 1.25 mmol/L In₂(SO₄)₃, 3.75 mmol/L SeO₂, 50 mmol/L Ga(NO₃)₃, 0.2 mol/L Na₂SO₄, 0.2 mol/L SDIPNS, pH=2.
The plating was carried out at current densities from −3 mA/cm²to −30 mA/cm², for 6 to 30 minutes.
FIG. 6 shows the compositions of the electroplated films analyzed by photon induced x-ray emission (PIXE). FIG. 6( a) shows the composition of the film plated at 20° C. and FIG. 6( b) shows the composition of the film plated at 50° C.
The gallium content can be controlled from 0 to 11.2% and the indium content can be controlled from 0% to 22.1%.
The foregoing examples illustrate and describe the present disclosures. However, they are by no means exclusive. Modifications and variations can be made along the direction outlined in the foregoing descriptions to achieve further improvement or broader range of control.
For example, by further changing the concentration of indium or gallium precursor chemicals in the solution, the composition of the film can be further changed. The indium composition in the above examples was limited under 30%, but it can be from 0 to 90% by changing the concentrations of precursors, plating temperature, plating current, and agitation. Similarly, gallium composition can be from 0 to 60% by changing the concentrations of precursors, plating temperature, plating current, and/or agitation. Persons skilled in the art once aware of the present disclosure would be able provide compounds with varying desired concentrations of gallium and/or indium in the absence of undue experimentation.
The above examples 2-4 illustrate the ability of the present disclosure to be used to tune the composition of the compound in the film. By tuning the composition, a continuously graded band gap structure, or a series of multiple junctions can be created. This further allows the improvement of the solar cell efficiency. In a solar device, the films of the present disclosure can be used as a light absorbing layer.
In addition, as mentioned above, the method disclosed in this disclosure was intended to improve the film quality, increase the gallium and indium content in the films, and to provide better control of the film composition of copper indium gallium selenide (CIGS) films by electrodeposition. But the method disclosed above should not be understood as limited in this application. I-III-VI compounds with other I, III, or VI elements, and I-III-VI compounds with additional other elements to alloy with the I-III-VI compounds should be considered as examples of the present disclosure as well.
The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “having” or “including” and not in the exclusive sense of “consisting only of.” The terms “a” and “the” as used herein are understood to encompass the plural as well as the singular.
The foregoing description of the disclosure illustrates and describes the present disclosure. Additionally, the disclosure shows and describes only the preferred embodiments but, as mentioned above, it is to be understood that the disclosure is capable of use in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the concept as expressed herein, commensurate with the above teachings and/or the skill or knowledge of the relevant art.
The embodiments described hereinabove are further intended to explain best modes known of practicing it and to enable others skilled in the art to utilize the disclosure in such, or other, embodiments and with the various modifications required by the particular applications or uses. Accordingly, the description is not intended to limit it to the form disclosed herein. Also, it is intended that the appended claims be construed to include alternative embodiments.
All publications, patents and patent applications cited in this specification are herein incorporated by reference, and for any and all purposes, as if each individual publication, patent or patent application were specifically and individually indicates to be incorporated by reference. In this case of inconsistencies, the present disclosure will prevail.

Claims

1. A bath for electroplating a I-III-VI compound comprising: water; a copper containing precursor dissolved in said water; a selenium containing precursor dissolved in said water ; and at least one member selected from the group consisting of an indium containing precursor dissolved in said water, a gallium containing precursor dissolved in said water and mixtures thereof; and at least one member selected from the group consisting of sulfur-containing organic compound dissolved in said water wherein one or more sulfur atoms directly bond with at least one carbon atom, a phosphorus-containing organic compound dissolved in said water wherein one or more phosphorus atoms directly bond with at least one carbon atom and mixtures thereof.

2. The bath according to claim 1 wherein said I-III-VI compound is copper indium gallium selenide.

3. The bath according to claim 2 wherein said copper indium gallium selenide has 0 atomic % to 90 atomic % indium and 0 atomic % to 60 atomic % gallium provided that at least one of said indium and gallium is a positive atomic % greater than 0.

4. The bath according to claim 1 wherein said copper containing precursor is copper sulfate, said selenium containing precursor is selenium oxide, said indium precursor is indium sulfate, said gallium precursor is gallium nitrate.

5. The bath according to claim 1 wherein said sulfur containing organic compound is at least one member selected from the group consisting of sulfonate, sulfonic acid, sulfinic acid, sulfinate, sulfonide, sulfinide, sulfide and disulfide.

6. The bath according to claim 1 wherein said phosphorus containing organic compound is at least one member selected from the group consisting of phosphonate, phosphonic acid, phosphinate, phosphinic acid, phosphonite and phosphinite.

7. The bath according to claim 1 wherein said bath comprises one or more inorganic chemicals to provide conductivity of the solution selected from the group consisting of sodium sulfate, potassium nitrate, and sodium phosphate.

8. The bath according to claim 1 wherein said bath further comprises one or more organic compounds as surfactant, wherein surfactant may or may not contains sulfur or phosphorus.

9. The bath according to claim 1 wherein said bath comprises one or more organic or inorganic chemicals to complex with the precursor chemicals selected from the group consisting of organic acids and ammonium salts.

10. The bath according to claim 1 wherein said bath comprises one or more organic or inorganic chemicals to buffer the solution pH.

11. (canceled)

12. The bath according to claim 1 wherein said bath further comprises one or more organic or inorganic chemicals to incorporate other elements into the film selected from the group consisting of C, B, N, O, S, H, Cl, Ag, Au, Cd, Zn, Al, Te, Ge, Sn and As.

13. A method of producing a I-III-VI compound in a thin film form by electroplating which comprises obtaining a bath comprising: water; a copper containing precursor dissolved in said water; a selenium containing precursor dissolved in said water; and at least one member selected from the group consisting of an indium containing precursor dissolved in said water, a gallium containing precursor dissolved in said water and mixtures thereof, and at least one member selected from the group consisting of sulfur-containing organic compound dissolved in said water wherein one or more sulfur atoms directly bond with at least one carbon atom, a phosphorus-containing organic compound dissolved in said water wherein one or more phosphorus atoms directly bond with at least one carbon atom and mixtures thereof;

immersing a cathode and an anode into said solution; and

applying a electric current or potential across said cathode and said anode to deposit a film of the I-III-VI compounds on the said cathode.

14. The method according to claim 13 wherein said I-III-VI compound is copper indium gallium selenide.

15. The method according to claim 13 wherein said sulfur containing organic compound is at least one member selected from the group consisting of sulfonate, sulfonic acid, sulfinic acid, sulfinate, sulfonide, sulfinide, sulfide and disulfide.

16. The method according to claim 13 wherein said phosphorus containing organic compound is at least one member selected from the group consisting of phosphonate, phosphonic acid, phosphinate, phosphinic acid, phosphonite and phosphinite.

17. The method according to claim 13 wherein said cathode is a conductive material selected from the group consisting of metal, conductive compound, conductive polymer, conductive glass, and a layer of conductive material on a substrate selected from the group consisting of Si, SiO₂, Si₃N₄, and steel.

18. (canceled)

19. The method according to claim 13 wherein said cathode comprises both conductive and nonconductive materials with one or more conductive materials exposed to the said solution.

20. The method according to claim 13 wherein the temperature of said solution is from about 5° C. to 80° C.

21. The method according to claim 13 wherein said potential and current is a constant, and has a current density from −1 mA/cm²to −100 mA/cm².

22. The method according to claim 13 wherein said potential and current is controlled in a waveform comprising sweeps, pulses, pulse reverses, sinusoidal.

23. The method according to claim 13 wherein said I-III-VI compound is annealed at a temperature higher than 20° C. after electroplating.

24. A method of producing a copper indium gallium selenide compound in a thin film form by electroplating, wherein the film has a composition gradient of gallium from 0 atomic % to 60 atomic % or a composition gradient of indium from 0 atomic % to 90 atomic %, comprising:

obtaining a bath comprising: water; a copper containing precursor dissolved in said water; a selenium containing precursor dissolved in said water; and at least one member selected from the group consisting of an indium containing precursor dissolved in said water, a gallium containing precursor dissolved in said water and mixtures thereof; and at least one member selected from the group consisting of sulfur-containing organic compound dissolved in said water wherein one or more sulfur atoms directly bond with at least one carbon atom, a phosphorus-containing organic compound dissolved in said water wherein one or more phosphorus atoms directly bond with at least one carbon atom and mixtures thereof;

immersing a cathode and an anode into said solution; and

applying a electric current or potential across the said cathode and said anode to deposit a film of I-III-VI compounds in a thin film form on the said cathode.

25. The method according to claim 24 wherein said cathode is rotating with the rotation rate controlled.

26. The method according to claim 24 wherein the temperature of said bath is controlled.

27. The method according to claim 24 wherein the cathode comprises a substrate for a solar device.