Hybrid window layer for photovoltaic cells

• US 20080166833A1
• Filed: 09/07/2007
• Published: 07/10/2008
• Est. Priority Date: 10/29/2003
• Status: Active Grant

• Current Assignee: University of Toledo
• Original Assignee: University of Toledo
• Inventors: Deng, Xunming
• Granted Patent: US 7,879,644 B2
• Time in Patent Office: Days
• 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

1-59. -59. (canceled)

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

(i) providing a transparent substrate;

(ii) depositing a transparent conducting oxide layer on the substrate;

(iii) depositing a second sub-p-layer on the substrate at a temperature relatively low for improved transparency of the second sub p-layer;

(iv) depositing a first sub-p-layer on the second sub-p-layer at a relatively higher temperature to form a good junction with an i-layer to be deposited thereon;

(v) depositing the i-layer on the first sub-p-layer at a temperature sufficiently low to avoid melting or damaging the p-layer; and

(vi) depositing a layer of n-type semi-conductor on the substrate at a temperature sufficiently low to avoid damage or melting the p and i-layers.

61. The method of claim 60, 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.

62. The method of claim 61, wherein an optimized level of hydrogen dilution is used to form the i-layer.

63. The method of claim 62, wherein the substrate comprises glass or plastic.

64. The method of claim 63, wherein the first and second sub-p-layers are deposited by a chemical vapor deposition process.

65. The method of claim 64, wherein the chemical vapor deposition process comprises plasma enhanced chemical vapor deposition.

66. The method of claim 65, in which the plasma enhanced chemical vapor deposition comprises radio frequency plasma enhanced chemical vapor deposition.

67. The method of claim 66, 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.

68. The method of claim 67, 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 around 1.6 e-V.

69. The method of claim 68, 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.

70-74. -74. (canceled)