PHOTOVOLTAIC DEVICE COMPRISING COMPOSITIONALLY GRADED INTRINSIC PHOTOACTIVE LAYER

• US 20110146769A1
• Filed: 12/22/2009
• Published: 06/23/2011
• Est. Priority Date: 12/22/2009
• Status: Active Grant

• Current Assignee: TRIAD National Security, LLC
• Original Assignee: Los Alamos National Security LLC (Government of the United States of America)
• Inventors: Hoffbauer, Mark A., Williamson, Todd L.
• Granted Patent: US 8,431,815 B2
• Time in Patent Office: Days
• US Class Current: 136/255
• CPC Class Codes: C08J 7/123 Treatment by wave energy or particle radiation C08J7/18 takes precedence
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/0296 including, apart from doping material or other impurities, only AIIBVI compounds, e.g. CdS, ZnS, HgCdTe
• CPC Class Codes: H01L 31/0304 including, apart from doping materials or other impurities, only AIIIBV compounds
• CPC Class Codes: H01L 31/03046 including ternary or quaternary compounds, e.g. GaAlAs, InGaAs, InGaAsP
• CPC Class Codes: H01L 31/0312 including, apart from doping materials or other impurities, only AIVBIV compounds, e.g. SiC
• CPC Class Codes: H01L 31/065 the potential barriers being only of the graded gap type
• CPC Class Codes: H01L 31/075 the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
• CPC Class Codes: H01L 31/1844 comprising ternary or quaternary compounds, e.g. Ga Al As, In Ga As P
• CPC Class Codes: H01L 31/1852 comprising a growth substrate not being an AIIIBV compound
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells

Abstract

Photovoltaic devices and methods of making photovoltaic devices comprising at least one compositionally graded photoactive layer, said method comprising providing a substrate; growing onto the substrate a uniform intrinsic photoactive layer having one surface disposed upon the substrate and an opposing second surface, said intrinsic photoactive layer consisting essentially of In_1-xA_xN,; wherein:

• • i. 0≦x≦1;
  • ii. A is gallium, aluminum, or combinations thereof; and
  • iii. x is at least 0 on one surface of the intrinsic photoactive layer and is compositionally graded throughout the layer to reach a value of 1 or less on the opposing second surface of the layer;
    wherein said intrinsic photoactive layer is isothermally grown by means of energetic neutral atom beam lithography and epitaxy at a temperature of 600° C. or less using neutral nitrogen atoms having a kinetic energy of from about 1.0 eV to about 5.0 eV, and wherein the intrinsic photoactive layer is grown at a rate of from about 5 nm/min to about 100 nm/min.

Claims

1. A method of making a photovoltaic device comprising a compositionally graded photoactive layer comprising:

a) providing a substrate;

b) growing onto the substrate at least one uniform intrinsic photoactive layer having one surface disposed upon the substrate and an opposing second surface, said intrinsic photoactive layer consisting essentially of In_1-xA_xN,;

wherein;

i. 0≦

x≦

1;

ii. A is gallium, aluminum, or combinations thereof; and

iii. x is at least 0 on one surface of the intrinsic photoactive layer and is compositionally graded throughout the layer to reach a value of 1 or less on the opposing second surface of the layer;

wherein said intrinsic photoactive layer is isothermally grown by means of energetic neutral atom beam lithography and epitaxy at a temperature of 600°

C. or less using neutral nitrogen atoms having a kinetic energy of from about 1.0 eV to about 5.0 eV, and wherein the intrinsic photoactive layer is grown at a rate of from about 5 nm/min to about 100 nm/min.

2. The method of claim 1, further comprising the step of growing a p-type doped active layer region and an n-type doped active layer region, both regions being disposed upon the opposing surface of the intrinsic photoactive layer, such that no portion of the p-type doped active layer region is in direct contact with the n-type doped active layer region.

3. The method of claim 2, wherein the p-doped active layer region and the n-doped active layer region each comprise a material having a lower band gap energy than the intrinsic photoactive layer.

4. The method of claim 1, wherein A is gallium.

5. The method of claim 1, wherein the intrinsic photoactive layer has bandgaps from about 0.7 eV to about 3.4 eV.

6. The method of claim 1, wherein the substrate is non-crystalline.

7. The method of claim 1, wherein the device is a photovoltaic device and wherein the substrate is free from electrical contacts.

8. The method of claim 2, further comprising growing an electrically conductive contact layer onto the p-doped active layer region and onto the n-doped active layer region.

9. The method of claim 8, further comprising attaching to the electrically conductive contact layer a means for conducting electrons to an electrical circuit.

10. The method of claim 2, wherein the p-doped active layer region and the n-doped active layer region each comprise a material having a lower band gap energy than the photoactive material.

11. The method of claim 1, wherein the photovoltaic device is a multi-junction photovoltaic device and has an efficiency of at least 50%.

12. The method of claim 1, wherein the photovoltaic device is a multi-junction photovoltaic device and has an efficiency of from about 30% to about 50%.

13. The method of claim 1, wherein the device is a single junction photovoltaic device and has an efficiency of from about 10% to about 30%.

14. A photovoltaic device comprising

a) a transparent substrate;

b) a uniform, compositionally graded, intrinsic photoactive layer having one surface disposed upon the substrate and an opposing second surface, said intrinsic photoactive layer consisting essentially of In_1-xA_xN,;

wherein;

i. 0≦

x≦

1;

ii. A is gallium, aluminum, or combinations thereof; and

iii. x is at least 0 on one surface of the intrinsic photoactive layer and is compositionally graded throughout the layer to reach a value of 1 or less on the opposing second surface of the layer;

c) a p-type doped active layer region and an n-type doped active layer region, both regions being disposed upon the opposing surface of the intrinsic photoactive layer, such that no portion of the p-type doped active layer region is in direct contact with the n-type doped active layer region;

d) an electrically conductive contact layer disposed upon the p-type doped active layer region and an electrically conductive contact layer disposed upon the n-type doped active layer region, such that no portion of the electrically conductive contact layer disposed upon the p-type doped active layer region is in contact with any portion of the electrically conductive contact layer disposed upon the n-type doped active layer region; and

,

e) a means for conducting electrons from the device to an electrical circuit which is in contact with the conducting contact layer.

15. The photovoltaic device of claim 14, wherein the p-doped active layer region and the n-doped active layer region each comprise a material having a lower band gap energy than the intrinsic photoactive layer.

16. The photovoltaic device of claim 14, wherein A is gallium.

17. The photovoltaic device of claim 14, wherein the intrinsic photoactive layer has bandgaps from about 0.7 eV to about 3.4 eV.

18. The photovoltaic device of claim 14, wherein the photovoltaic device is a multi junction photovoltaic device and has an efficiency of at least 50%.

19. The photovoltaic device of claim 14, wherein the photovoltaic device is a multi junction photovoltaic device and has an efficiency of from about 30% to about 50%.

20. The photovoltaic device of claim 14, wherein the device is a single junction photovoltaic device and has an efficiency of from about 10% to about 30%.