Hybrid window layer for photovoltaic cells

• US 8,030,120 B2
• Filed: 09/07/2007
• Issued: 10/04/2011
• Est. Priority Date: 10/29/2003
• Status: Expired due to Fees

• Current Assignee: University of Toledo
• Original Assignee: University of Toledo
• Inventors: Deng, Xunming, Liao, Xianbo, Du, Wenhui
• Primary Examiner(s): Wilczewski; Mary
• Assistant Examiner(s): THOMAS, TONIAE M
• Application Number:
  US11/899,797
• Publication Number:
  US 20080000524A1
• Time in Patent Office: 1,488 Days
• Field of Search: 136/255, 136/256, 136/261, 136/258, 438 96- 98, 438/482, 257/E21.297, 257/E31.002
• US Class Current: 438/96
• CPC Class Codes: H01L 31/03762 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/03765 including AIVBIV compounds or alloys, e.g. SiGe, SiC
• CPC Class Codes: H01L 31/03921 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/056 the light-reflecting means being of the back surface reflector [BSR] type
• CPC Class Codes: H01L 31/0745 comprising a AIVBIV heterojunction, e.g. Si/Ge, SiGe/Si or Si/SiC solar cells
• CPC Class Codes: H01L 31/202 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/204 including AIVBIV alloys, e.g. SiGe, SiC
• CPC Class Codes: Y02E 10/52 PV systems with concentrators
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

Claims

1. A method for manufacturing a solar cell comprising the steps of:

(i) providing a substrate;

(ii) depositing a layer of n-type semi-conductor on the substrate at a temperature that is one of 300°

C. and sufficiently low to avoid damage or melting the substrate;

(iii) depositing an i-layer on the n-layer at a temperature that is one of 300°

C. and sufficiently low to avoid melting or damaging the n-layer;

(iv) depositing a first sub-p-layer on the i-layer at a first temperature sufficiently high to form a good junction with the i-layer; and

(v) depositing a second sub-p-layer on the first sub-p-layer at a temperature lower than the first temperature at which the first sub-p-layer is deposited.

2. The method of claim 1, further including depositing a layer of a transparent conductive oxide on the second p-layer.

3. The method of claim 2, wherein a current collection layer is deposited onto the substrate prior to deposition of the n-layer onto the substrate.

4. The method of claim 1, wherein during the i-layer deposition an optimized GeH₄ to Si₂H₆ ratio provides a Ge content suitable for forming a high efficiency single-junction solar cell.

5. The method of claim 4, wherein an optimized level of hydrogen dilution is used to form the i-layer.

6. The method of claim 5, wherein the substrate comprises glass or metal including aluminum, bismuth, iron, niobium, titanium or steel.

7. The method of claim 1, wherein the first and second sub-p-layers are deposited by a chemical vapor deposition process.

8. The method of claim 7, wherein the chemical vapor deposition process comprises plasma enhanced chemical vapor deposition.

9. The method of claim 8, in which the plasma enhanced chemical vapor deposition comprises radio frequency plasma enhanced chemical vapor deposition.

10. The method of claim 9, wherein the first and second p-layers amorphous silicon-containing material selected from the group consisting of hydrogenated amorphous silicon, hydrogenated amorphous carbon, and hydrogenated amorphous silicon germanium.

11. The method of claim 10, wherein the i-layer comprises hydrogenated amorphous silicon germanium having a bandgap ranging from about 1.4 e-V to 1.6 e-V and wherein the first and second sub p-layers comprise amorphous silicon with a bandgap of 1.4 e-V.

12. The method of claim 11, wherein the plasma enhanced chemical vapor deposition is by at least one of the following:

cathodic direct current glow discharge, anodic direct current glow discharge, radio frequency glow discharge, very high frequency (VHF) glow discharge, alternate current glow discharge, or microwave glow discharge at a pressure ranging from about 0.5 to about 5 TORR with a dilution ratio of dilutant to feedstock (deposition gas) ranging from about 5;

1 to about 200;

1.