# US 2013/0153025 A1 · Method for producing a solar cell having a textured front face and corresponding solar cell

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- Number: US 2013/0153025 A1
- Document ID: US20130153025A1
- Status: Published application
- Kind: A1
- Application number: 13/819,205
- Filed: 2011-08-23
- Published: 2013-06-20
- Earliest claimed: 2010-08-27
- Assignees: Universität Konstanz
- Inventors: Giso Hahn; Amir Dastgheib-Shirazi
- Web page: https://patentgrep.com/patent/US20130153025A1

## CPC

- H10F 77/703: {of the semiconductor bodies, e.g. textured active layers}
- H10F 77/707: {of the substrates or of layers on substrates, e.g. textured ITO layer on a glass substrate}
- Y02E 10/50: Photovoltaic [PV] energy
- 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

## Abstract

The invention relates to a method for producing a solar cell and to a solar cell which can be produced accordingly. On a solar cell substrate, first a ridged texture, which may for example comprise pyramids produced by alkaline etching, is formed both on a front face and on a rear face of the solar cell substrate. Then an etching barrier layer is applied to the front face of the solar cell substrate. Next the texture on the rear face of, the solar cell substrate is smoothed by etching in an isotropically acting etching solution which for example contains acid, wherein the front face is protected by the etching barrier layer. Thus, ridged structures on the rear face can be avoided and in this way reflection can be increased and surface passivation can be improved, both of which can lead to an increased potential efficiency. At the same time an emitter layer formed over the entire surface of the solar cell substrate on the rear face can be removed during etching, so that electrical isolation of the front face contacts and the rear face contacts may be superfluous.

## Claims

### Claim 1

Method for producing a solar cell, comprising:
providing a solar cell substrate;
forming a texture at a front face and at a rear face of the solar cell substrate;
applying an etching barrier layer to the front face of the solar cell substrate; and
smoothing the texture at the rear face of the solar cell substrate by etching in an isotropically acting etching solution for removal of about 1 μm to 20 μm of substrate material, the texture being realized with an angular structure, and edges of the texture structure being rounded, in the form of an undulation, as the texture is being smoothed.

### Claim 2 (depends on 1)

Method according to claim 1, wherein the isotropically acting etching solution contains acid.

### Claim 3 (depends on 2)

Method according to claim 2, wherein the acid-containing etching solution contains hydrofluoric acid.

### Claim 4 (depends on 1)

Method according to claim 1, wherein the etching barrier layer is realized with a viscous paste.

### Claim 5 (depends on 1)

Method according to claim 1, wherein the etching barrier layer is applied by a screen printing technique or an ink-jet technique.

### Claim 6 (depends on 1)

Method according to claim 1, wherein the etching is performed in such a way that less than 20 μm is removed from the rear face of the solar cell substrate.

### Claim 7 (depends on 1)

Method according to claim 1, wherein the etching is performed in a period of less than 5 minutes.

### Claim 8 (depends on 1)

Method according to claim 1, wherein the etching solution during etching is at a temperature in the range from 10° C. to 40° C.

### Claim 9 (depends on 1)

Method according to claim 1, wherein, before the texture is smoothed, an emitter layer is realized both at the front face and at the rear face of the solar cell substrate, and wherein the emitter layer is removed at the rear face of the solar cell substrate as the texture is being smoothed.

### Claim 10 (depends on 1)

Method according to claim 1, wherein, after the texture has been smoothed, a passivation layer is applied to the rear face of the solar cell substrate.

### Claim 11 (depends on 1)

Method according to claim 1, wherein, after the etching barrier layer has been applied to the front face of the solar cell substrate, a selective emitter is realized by etching in an etching solution.

### Claim 12 (depends on 11)

Method according to claim 11, wherein the etching barrier layer has two partial layers, disposed above one another, that have differing resistance capabilities in respect of stripping solutions used to remove the partial layers.

### Claim 13

Solar cell comprising:
a solar cell substrate, which at a front face has an angular texture and which at a rear face has a rounded texture in the form of an undulation.

### Claim 14 (depends on 13)

Solar cell according to claim 13, further comprising a selective emitter at the front face of the solar cell substrate.

### Claim 15 (depends on 1)

Method according to claim 1, wherein the texture at the rear face is smoothed by removal of 3 μm to 20 μm of substrate material.

### Claim 16 (depends on 1)

Method according to claim 1, wherein the texture at the rear face is smoothed by removal of 3 μm to 10 μm of substrate material.