# US 2013/0153015 A1 · Method for forming solar cells

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- Number: US 2013/0153015 A1
- Document ID: US20130153015A1
- Status: Published application
- Kind: A1
- Application number: 13/326,458
- Filed: 2011-12-15
- Published: 2013-06-20
- Earliest claimed: 2011-12-15
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Wen-Chin LEE; Yung-Sheng CHU; Wen-Tsai YEN; Liang-Sheng YU
- Web page: https://patentgrep.com/patent/US20130153015A1

## CPC

- H10F 71/129: {Passivating}
- H10F 10/167: comprising Group I-III-VI materials, e.g. CdS/CuInSe2 [CIS] heterojunction photovoltaic cells
- H10F 77/169: Thin semiconductor films on metallic or insulating substrates
- H10F 77/1694: {the films including Group I-III-VI materials, e.g. CIS or CIGS}
- H10F 77/1696: {the films including Group II-VI materials, e.g. CdTe or CdS}
- H10F 77/244: {made of transparent conductive layers, e.g. transparent conductive oxide [TCO] layers}
- H10F 77/311: {for photovoltaic cells}
- Y02E 10/541: CuInSe2 material PV cells
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A thin film solar cell and process for forming the same. The solar cell includes a bottom electrode layer, semiconductor light absorbing layer, top electrode layer, and a protective moisture barrier layer. In some embodiments, the barrier layer is formed of a water-insoluble material. The barrier layer helps protect the top electrode layer from exposure and damage caused by water and oxygen.

## Claims

### Claim 1

A thin film solar cell comprising:
a bottom electrode layer formed on a substrate;
a semiconductor absorber layer formed on the bottom electrode layer;
a buffer layer formed on the absorber layer;
a top electrode layer formed on the buffer layer, the top electrode layer being electrically connected to the bottom electrode layer through a P2 scribe line defining a vertical channel extending through the buffer and absorber layers;
a protective first moisture barrier layer formed on the top electrode layer for protecting the top electrode layer from environmental moisture and oxygen damage, wherein the first moisture barrier layer is formed of a material that is insoluble in water; and
an encapsulant formed on the first moisture barrier layer.

### Claim 2 (depends on 1)

The solar cell of claim 1, wherein the encapsulant contains EVA and butyl.

### Claim 3 (depends on 1)

The solar cell of claim 1, wherein the first moisture barrier layer extends into the scribe line.

### Claim 4 (depends on 1)

The solar cell of claim 1, wherein the P2 scribe line is at least partially filled with material from the top electrode layer that contacts the bottom electrode, the first moisture barrier layer covering exposed sidewall portions of the top electrode layer material within the P2 scribe line.

### Claim 5 (depends on 1)

The solar cell of claim 1, wherein the first moisture barrier layer has a thickness from about 10 nm to about 150 nm.

### Claim 6 (depends on 1)

The solar cell of claim 1, wherein a material forming the first moisture barrier layer is a stable oxide compound having a Gibbs Free Energy of at least −600 KJ/mol.

### Claim 7 (depends on 1)

The solar cell of claim 1, wherein the first barrier layer material is selected from the group consisting of MgO, In2O3, CaO, Ga2O3, Cr2O3, Ta2O5, TiO2, ZrO2, Al2O3, HfO2, La2O3, Lu2O3, SiONx, SiNx, and SiOx.

### Claim 8 (depends on 1)

The solar cell of claim 1, wherein the absorber layer is comprised of p-type chalcogenide materials or CdTe.

### Claim 9 (depends on 1)

The solar cell of claim 1, wherein the absorber layer is comprised of a material selected from the group consisting of Cu(In,Ga)Se2, Cu(In,Ga)(Se, S)2, CuInSe2, CuGaSe2, CuInS2, and Cu(In,Ga)S2.

### Claim 10 (depends on 1)

The solar cell of claim 1, wherein the top electrode is an n-type material selected from the group consisting of zinc oxide, aluminum doped zinc oxide, gallium doped zinc oxide, indium doped zinc oxide, fluorine tin oxide, indium tin oxide, indium zinc oxide, antimony tin oxide (ATO), and a carbon nanotube layer.

### Claim 11 (depends on 1)

The solar cell of claim 1, further comprising a P3 scribe line forming a vertical channel through the solar cell to the substrate, wherein the first moisture barrier layer extends into the P3 scribe line.

### Claim 12 (depends on 1)

The solar cell of claim 1, further comprising a second moisture barrier layer formed on the first moisture barrier layer, the second moisture barrier being formed of the same or different material than the first moisture barrier.

### Claim 13 (depends on 12)

The solar cell of claim 12, wherein the second moisture barrier layer extends into the P2 scribe line.

### Claim 14

A thin film solar cell comprising:
a bottom electrode layer formed on a substrate;
a semiconductor absorber layer formed on the bottom electrode layer;
a buffer layer formed on the absorber layer;
a top electrode layer formed on the buffer layer and made of an electrically conductive TCO material, the top electrode layer being electrically connected to the bottom electrode layer through a P2 scribe line defining a vertical channel extending through the buffer and absorber layers; and
a protective first moisture barrier layer deposited on the top electrode layer for protecting the top electrode layer from environmental moisture and oxygen damage, wherein the first moisture barrier layer is made of a material that is insoluble in water, the first moisture barrier material covering portions of the top electrode layer material disposed in the P2 scribe line to protect the top electrode material from moisture and oxygen damage.

### Claim 15 (depends on 14)

The solar cell of claim 14, further comprising an encapsulant formed above the first moisture barrier layer.

### Claim 16 (depends on 14)

The solar cell of claim 14, further comprising a P3 scribe line forming a vertical channel through the solar cell to the substrate, wherein the first moisture barrier layer extends into the P3 scribe line and covers exposed portions of the top electrode layer therein.

### Claim 17 (depends on 14)

The solar cell of claim 14, further comprising:
a P3 scribe line forming a vertical channel through the solar cell to the substrate; and
a discrete second moisture barrier layer formed on the first moisture barrier layer, the second moisture barrier being formed of the same or different material than the first moisture barrier, wherein the second moisture barrier layer extends into the P3 scribe line and covers exposed portions of the top electrode layer therein.

### Claim 18

A method for forming a thin film solar cell comprising:
depositing a conductive bottom electrode layer on a substrate;
depositing an absorber layer on the bottom electrode layer;
depositing a buffer layer on the absorber layer;
cutting an open P2 scribe line in the absorber layer, the scribe line forming an open channel with exposed sidewalls on the absorber layer from exposed portions of the absorber and buffer layers;
depositing a top electrode layer on the buffer layer after cutting the P2 scribe line, material from the top electrode layer at least partially filling the P2 scribe line;
depositing a first moisture barrier layer made of a water-insoluble material on the top electrode layer; and
covering portions of the top electrode layer material in the P2 scribe lines with the first moisture barrier layer material for protection against water and oxygen damage to the top electrode layer material within the P2 scribe line.

### Claim 19 (depends on 18)

The method of claim 18, further comprising cutting a P3 scribe line before depositing the first moisture barrier layer, wherein the steps of depositing the first moisture barrier layer also covers exposed sidewalls of the top electrode layer within the P3 scribe line.

### Claim 20 (depends on 18)

The method of claim 18, further comprising:
cutting a P3 scribe line after depositing the first moisture barrier layer;
depositing a second moisture barrier layer on the first moisture barrier layer after forming the P3 scribe line; and
covering exposed sidewall portions of the top electrode layer material in the P3 scribe lines with the second moisture barrier layer material for protection against moisture and oxygen damage to the top electrode layer material within the P3 scribe line.