Claims
- 1. A photoelectrochemical solar cell, comprising:
- a photoanode of n-CuInSe.sub.2 with a surface layer of oxidized indium thereon;
- a cathode; and
- an electrolyte providing a liquid junction between said photoanode and cathode comprising an iodine/iodide redox couple, and predetermined amounts of Cu and In ions sufficient to provide enhanced long term stability.
- 2. The photoelectrochemical solar cell of claim 1, wherein said photoanode carries an etched and annealed surface below said surface layer of oxidized indium.
- 3. The photoelectrochemical solar cell of claim 2, wherein said electrolyte comprises a combination of iodide ions in concentration greater than 3 M; iodine in concentration greater than 0.01 M but less than 0.1 M; Cu.sup.+ ions in concentration between about 0.02 to 0.2 M; and In.sup.3+ ions in concentration between about 0.005 to 0.2 M.
- 4. The photoelectrochemical solar cell of claim 1, wherein the electrolyte has a pH of between about 4 to 9.
- 5. A method of fabricating a photoelectrochemical solar cell of the type having a photoanode of n-CuInSe.sub.2 electrode material and having an iodine/iodide redox couple and a predetermined final concentration of Cu.sup.+ ions in a liquid electrolyte, comprising the steps of:
- etching the electrode material by a chemical means;
- heating the etched electrode material;
- depositing a film of indium on said etched surface; and
- oxidizing the deposited film.
- 6. The method of claim 5, wherein said chemical etching means comprises Br.sub.2 /MeOH.
- 7. The method of claim 5, wherein said etching step comprises contacting the electrode material with a solution of Br.sub.2 /MeOH having a concentration of from 1% to 5% (V/V) for a period of time between 60 seconds and 5 seconds.
- 8. The method of claim 5, wherein said heating of the etched electrode is conducted at a temperature of not substantially more than about 150.degree. C. for a time of not substantially more than approximately 3 hours.
- 9. The method of claim 5, wherein said heating of the etched electrode is conducted at a temperature between about 80.degree. C. and 150.degree. C. for a time between about one-half hour and five hours.
- 10. The method of claim 5, wherein said indium film is thermally oxidized by heating in an atmosphere containing oxygen.
- 11. The method of claim 10, wherein said indium film is oxidized by heating in air at a temperature of no more than about 90.degree. C. for a time of no more than about 3.5 hours.
- 12. The method of claim 5, wherein an oxidized film layer of indium is formed which is between about 20 and 300 Angstroms in thickness.
- 13. The method of claim 5, wherein said step of depositing a film of indium is conducted to produce a film thickness of at least about 20 Angstroms.
- 14. The method of claim 5, including the further step of immersing the oxidized electrode in an electrolyte of pH between about 4 and 9.
- 15. The method of claim 5, further comprising adding to said electrolyte In.sup.3+ ions in a predetermined concentration.
- 16. The method of claim 15, wherein said predetermined concentration of In.sup.3+ ions is between about said final concentration of Cu.sup.+ ions and one-fourth of the final concentration of Cu.sup.+ ions.
- 17. The method of claim 16, wherein the concentration of Cu.sup.+ ions is approximately 0.02 to 0.2 M.
- 18. The method of claim 15, wherein said predetermined concentration of In.sup.3+ ions is about 0.05 M.
- 19. The method of claim 5, wherein said heating of the etched electrode material, is conducted in an atmosphere comprising oxygen.
- 20. An improved photoelectrochemical solar cell of the type having n-CuInSe.sub.2 electrode material in a liquid electrolyte comprising an iodine/iodide redox couple and a predetermined concentration of Cu ions selected to provide enhanced long term stability, wherein the improvement comprises a film of oxidized indium metal formed on the surface of said n-CuInSe.sub.2 electrode material.
- 21. The improved photoelectrochemical solar cell of claim 20, wherein the improvement further comprises an etched and subsequently annealed-in-air electrode material surface underlying said surface film of oxidized indium.
- 22. The improved photoelectrochemical solar cell of claim 20, further comprising a predetermined concentration of indium ions in said electrolyte.
- 23. The photoelectrochemical solar cell of claim 22, wherein the predetermined concentration of In ions is approximately 0.005 to 0.2 M.
- 24. The photoelectrochemical solar cell of claim 22, wherein the electrolyte has a pH of between 4 and 9.
CONTRACTUAL ORIGIN OF THE INVENTION
The U.S. Government has rights in this invention pursuant to Contract No. DE-AC02-83CH10093 between the U.S. Department of Energy and the Solar Energy Research Institute, a division of the Midwest Research Institute.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4180625 |
Wagner |
Dec 1979 |
|
4386142 |
Hodes et al. |
May 1983 |
|
4388382 |
Bachmann et al. |
Jun 1983 |
|
Non-Patent Literature Citations (2)
Entry |
K. J. Bachmann et al., Surface Science, vol. 138, pp. 475-487, (1984). |
S. Menezes, Appl. Phys. Lett., vol. 45, pp. 148-149, (1984). |