Hybrid emitter all back contact solar cell

Patent metadata

Field	Value
Publication number	US-2016204288-A1
Application number	US-201615067960-A
Country	US
Kind code	A1
Filing date	Mar 11, 2016
Priority date	Dec 19, 2012
Publication date	Jul 14, 2016
Grant date	—

Abstract

An all back contact solar cell has a hybrid emitter design. The solar cell has a thin dielectric layer formed on a backside surface of a single crystalline silicon substrate. One emitter of the solar cell is made of doped polycrystalline silicon that is formed on the thin dielectric layer. The other emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The solar cell includes contact holes that allow metal contacts to connect to corresponding emitters.

First claim

What is claimed is:

1 . A method of manufacturing a solar cell, the method comprising:
forming a thin dielectric layer on a single crystalline silicon substrate; forming a first emitter on the thin dielectric layer on a backside of the solar cell, the first emitter comprising polycrystalline silicon that is doped with dopants of a first polarity, the backside of the solar cell being opposite a front side of the solar cell that faces the sun during normal operation; forming a second emitter in the single crystalline silicon substrate on the backside the solar cell, the second emitter comprising single crystalline silicon that is doped with dopants of a second polarity opposite to the first polarity; and forming a first metal contact connected to the first emitter and a second metal contact connected to the second emitter on the backside of the solar cell.

2 . The method of claim 1 , wherein the single crystalline silicon substrate is doped with N-type dopants, the polycrystalline silicon of the first emitter is doped with P-type dopants, and the single crystalline silicon of the second emitter is doped with N-type dopants.

3 . The method of claim 1 , further comprising:
forming a first layer of material on the thin dielectric layer and the first emitter; forming a contact hole through the first layer of material but not through the thin dielectric layer to expose the first emitter; and forming another contact hole through the first layer of material and the thin dielectric layer to expose the second emitter.

4 . The method of claim 1 , wherein forming the first emitter comprises:
depositing a polycrystalline silicon layer on the thin dielectric layer; and patterning the polycrystalline silicon layer to form the first emitter.

5 . The method of claim 1 , wherein forming the first emitter comprises:
printing silicon nanoparticles on the thin dielectric layer; and thermally processing the silicon nanoparticles to form polycrystalline silicon.

6 . The method of claim 1 , wherein the thin dielectric layer comprises silicon dioxide that is thermally grown directly on a surface of the single crystalline silicon substrate.

7 . The method of claim 1 , wherein forming the second emitter comprises:
forming a dopant source layer on the thin dielectric layer; and diffusing dopants from the dopant source layer through the thin dielectric layer and into the single crystalline silicon substrate.

8 . The method of claim 7 , wherein the dopant source layer comprises phosphorus-silicate glass (PSG).

9 . A method of manufacturing a solar cell, the method comprising:
forming a thin dielectric layer on a single crystalline silicon substrate; forming a first emitter of the solar cell on the thin dielectric layer between the single crystalline silicon substrate and the first emitter, the first emitter comprising polycrystalline silicon doped to have a first polarity; and forming a second emitter and a third emitter of the solar cell in the single crystalline silicon substrate, the second emitter and the third emitter comprising single crystalline silicon doped to have a second polarity opposite the first polarity, the first emitter being formed between the second and third emitters, the second and third emitters being formed starting from opposing ends of the first emitter.

10 . The method of claim 9 , further comprising:
forming a first metal contact connected to the first emitter on a backside of the solar cell, the backside being opposite a front side of the solar cell that faces the sun during normal operation; forming a second metal contact connected to the second emitter on the backside of the solar cell; and forming a third metal contact connected to the third emitter on the backside of the solar cell.

11 . The method of claim 9 , wherein the thin dielectric layer comprises silicon dioxide and is formed directly on a surface of the single crystalline silicon substrate.

12 . The method of claim 10 , further comprising:
forming a first layer of material on the first emitter and the backside surface of the single crystalline silicon substrate, wherein the first metal contact connects to the first emitter through the first layer of material but not through the thin dielectric layer.

13 . The method of claim 12 , wherein the second metal contact connects to the second emitter through the first layer of material and the thin dielectric layer.

14 . The method of claim 9 , wherein the first emitter is a P-type doped emitter, the second emitter is an N-type doped emitter, and the single crystalline silicon substrate is doped with an N-type dopant.

15 . The method of claim 9 , wherein a total area of the first emitter and other emitters of the solar cell that comprise polycrystalline silicon covers at least 80% of a total area of a backside surface of the single crystalline silicon substrate.

16 . A method of manufacturing a solar cell, the method comprising:
forming a thin dielectric formed on a single crystalline silicon substrate; forming a first emitter of the solar cell on the thin dielectric, the first emitter comprising doped polycrystalline silicon; forming a second emitter of the solar cell in the single crystalline silicon substrate, the second emitter comprising doped single crystalline silicon; forming a third emitter of the solar cell in the single crystalline silicon substrate, the third emitter comprising doped single crystalline silicon, wherein the first emitter is formed between the second and third emitters, the second and third emitters are formed starting from opposing ends of the first emitter, and the thin dielectric is formed between the single crystalline silicon substrate and the first emitter.

17 . The method of claim 16 , wherein the first emitter is doped with P-type dopants, the second emitter is doped with N-type dopants, and the single crystalline silicon substrate is doped with N-type dopants.

18 . The method of claim 16 , wherein the thin dielectric comprises silicon dioxide.

19 . The method of claim 16 , further comprising:
forming a metal contact that is connected to the second emitter through a contact hole in the thin dielectric layer.

20 . The method of claim 16 , wherein the solar cell is an all back contact solar cell.

Assignees

• Sunpower Corp

Inventors

• Loscutoff Paul
• Rim Seung

Classifications

• H10F77/219 Primary

  Arrangements for electrodes of back-contact photovoltaic cells · CPC title

• H10F10/146 Primary

  Back-junction photovoltaic cells, e.g. having interdigitated base-emitter regions on the back side · CPC title

• H10F77/122

  comprising only Group IV materials · CPC title

• H10F77/1642

  including only Group IV materials · CPC title

• H10F77/227

  for emitter wrap-through [EWT] photovoltaic cells, e.g. interdigitated emitter-base back-contacts · CPC title