Hybrid window layer for photovoltaic cells

• US 7,667,133 B2
• Filed: 10/29/2003
• Issued: 02/23/2010
• Est. Priority Date: 10/29/2003
• Status: Expired due to Fees

• Current Assignee: United States Department of Energy (Government of the United States of America)
• Original Assignee: University of Toledo
• Inventors: Deng, Xunming
• Primary Examiner(s): BARTON, JEFFREY THOMAS
• Application Number:
  US10/696,545
• Publication Number:
  US 20050092357A1
• Time in Patent Office: 2,309 Days
• Field of Search: 136/255, 136/256, 136/258
• US Class Current: 136/255
• 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 novel photovoltaic solar cell comprising:

at least one absorber layer, and

at least one doped window layer having at least two p-type sub-window layers, wherein a first p-type sub-window layer is adjacent the absorber layer and forms a desirable junction with the absorber layer and wherein a second p-type sub-window layer is adjacent the first p-type sub-window layer and has high optical transmission;

wherein the absorber layer comprises at least one of amorphous silicon (a-Si;

H), amorphous silicon germanium (a-Si_(1-x)Ge_X;

H), nanocrystalline silicon (nc-Si;

H), microcrystalline silicon (μ

c-Si;

H), polycrystalline silicon (poly-Si;

H), or other combinations and mixtures thereof;

the first and second p-type sub-window layers each being comprised of nanocrystalline silicon;

wherein the second p-type sub-window layer has a transparency and a thickness that are both greater than the transparency and the thickness of the first p-type sub-window layer.

2. The solar cell of claim 1, further comprising a substrate selected from at least one of:

glass, metal or plastic.

3. The solar cell of claim 2, further comprising a transparent conductive oxide layer adjacent the second p-type sub-window-layer.

4. The solar cell of claim 1, further comprising a buffer semi-conductor layer between the absorber-layer and the first p-type sub-window layer.

5. The solar cell of claim 1, the first p-type sub-window layer being formed by deposition at a first temperature, and the second p-type sub-window layer being formed by deposition at a second temperature that is lower than the first temperature.

6. The solar cell of claim 1, wherein the first p-type sub-window layer is formed from the same thin film silicon based material as the second p-type sub-window layer.

7. A novel photovoltaic solar cell comprising:

a substrate;

at least one absorber layer, and

at least one doped window layer having at least two sub-window layers, wherein the first sub-window layer is adjacent the absorber layer and forms a desirable junction with the absorber layer and wherein the second sub-window layer is adjacent the first sub-window layer and has high optical transmission;

wherein the absorber layer comprises at least one of amorphous silicon (a-Si;

H), amorphous silicon germanium (a-Si_(1-x)Ge_x;

H), nanocrystalline silicon (nc-Si;

H), microcrystalline silicon (μ

c-Si;

H), polycrystalline silicon (poly-Si;

H), or other combinations and mixtures thereof;

the first and second sub-window p-type layers each being comprised of a;

nanocrystalline silicon;

wherein the second sub-window p-type layer has a transparency greater than the first sub-window p-type layer, and wherein there is a minimal mismatch between the bandgap of the first sub-window p-type layer and the bandgap of the absorber layer that is adjacent to the first sub-window p-layer; and

,

wherein the substrate comprises a stainless steel metal, the first and second p-type sub-window layers comprise a-Si;

H, the absorber layer comprises a-SiGe;

H, and the n-layer comprises a-Si;

H.

8. The solar cell of claim 7, the first p-type sub-window layer being formed by deposition at a first temperature, and the second p-type sub-window being formed by deposition at a second temperature that is lower than the first temperature.