Solar cell having rear buffer layer and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-2016005899-A1
Application number	US-201314770455-A
Country	US
Kind code	A1
Filing date	Aug 6, 2013
Priority date	Mar 12, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

The invention relates a thin-film solar cell. In the related art, a buffer layer, a transparent electrode, and a grid electrode are formed on a light absorption layer, but in the invention, the buffer layer and the transparent electrode are not formed on a light absorption layer, and the buffer layer, the transparent electrode, and the grid electrode are formed under a CIGS face such that solar light is directly input to the light absorption layer without obstacles, and the first electrode and the buffer layer are patterned in a saw-toothed structure to engage with each other to reduce a distance by which electrons or holes generated by absorbing light energy move to the electrode or the buffer layer.

First claim

1 . A solar cell comprising:
a substrate; a first electrode that is formed in a specific area on the substrate; a buffer layer that is disposed separately at a predetermined gap from the first electrode on the substrate; and a light absorption layer that is formed on the first electrode, the buffer layer, and the substrate between the first electrode and the buffer layer, wherein the first electrode and the buffer layer are electrically separated from each other by a material of the light absorption layer, and wherein the buffer layer is positioned under the light absorption layer to increase the amount of incident light of the light absorption layer.

2 . The solar cell according to claim 1 , wherein one face of the first electrode opposed to the buffer layer has a saw-toothed pattern including a first electrode protrusion portion, a first electrode depression portion, and a connection portion electrically connecting the first electrode protrusion portion and the first electrode depression portion,
wherein the first electrode protrusion portion is inserted into a depression portion of the buffer layer and is disposed separately at a predetermined space, and wherein a protrusion portion of the buffer layer is inserted into the first electrode depression portion and is disposed separately at a predetermined space.

3 . The solar cell according to claim 1 , wherein the first electrode includes any one of nickel, copper, and molybdenum.

4 . The solar cell according to claim 1 , wherein the buffer layer includes CdS, CdZnS, ZnS, Zn(S,O), Zn(OH,S), ZnS(O,OH), ZnSe, ZnInS, ZnInSe, ZnMgO, Zn(Se,OH), ZnSnO, ZnO, InSe, InOH, In(OH,S), In(OOH,S), and In(S,O).

5 . The solar cell according to claim 1 , further comprising a grid electrode coming in contact with the buffer layer,
wherein the grid electrode includes at least any one of aluminum and nickel.

6 . The solar cell according to claim 1 , further comprising a reflection preventing layer on the light absorption layer.

7 . The solar cell according to claim 6 , wherein the reflection preventing layer includes:
a first reflection preventing layer that is formed on the light absorption layer and includes Al 2 O 3 ; and a second reflection preventing layer that is formed on the first reflection preventing layer and includes MgF 2 .

8 . The solar cell according to claim 1 , further comprising a second electrode between the substrate and the buffer layer.

9 . The solar cell according to claim 8 , wherein the second electrode includes at least any one of zinc oxide, gallium oxide, aluminum oxide, indium oxide, lead oxide, copper oxide, titanium oxide, tin oxide, iron oxide, tin dioxide, and indium tin oxide.

10 . The solar cell according to claim 1 , wherein the light absorption layer includes any one selected from a CIS/CIGS-based compound group including Cu—In—Se, Cu—In—S, Cu—Ga—S, Cu—Ga—Se, Cu—In—Ga—Se, Cu—In—Ga—Se—(S,Se), Cu—In—Al—Ga—(S,Se), and Cu—In—Al—Ga—Se—S.

11 . A method of manufacturing a solar cell comprising:
(i) a step of preparing a substrate; (ii) a step of forming a first electrode on the substrate; (iii) a step of patterning the first electrode to remove the first electrode formed at a specific portion of the substrate; (iv) a step of forming a buffer layer on the first electrode and the substrate; (v) a step of patterning the buffer layer to dispose the buffer layer at a predetermined gap from the first electrode; and (vi) a step of forming a light absorption layer on the first electrode, the buffer layer, and the substrate between the first electrode and the buffer layer.

12 . A method of manufacturing a solar cell comprising:
(i) a step of preparing a substrate; (ii) a step of forming a first electrode on the substrate; (iii) a step of patterning the first electrode to remove the first electrode formed at a specific portion of the substrate; (iv) a step of forming a second electrode on the first electrode and the substrate; (v) a step of patterning the second electrode to dispose the second electrode at a predetermined gap from the first electrode; (vi) a step of forming a buffer layer on the first electrode, the second electrode, and the substrate; (vii) a step of patterning the buffer layer to dispose the buffer layer at a predetermined gap from the first electrode; and (viii) a step of forming a light absorption layer on the first electrode, the buffer layer, and the substrate between the first electrode and the buffer layer.

13 . The method of manufacturing a solar cell according to claim 11 , wherein the first electrode includes any one of molybdenum, nickel, and copper, and
wherein the first electrode is formed by any one method of sputtering, thermal evaporation, E-beam evaporation, and electrodeposition.

14 . The method of manufacturing a solar cell according to claim 11 , wherein the buffer layer includes any one of CdS, CdZnS, ZnS, Zn(S,O), Zn(OH,S), ZnS(O,OH), ZnSe, ZnInS, ZnInSe, ZnMgO, Zn(Se,OH), ZnSnO, ZnO, InSe, InOH, In(OH,S), In(OOH,S), and In(S,O), and
wherein the buffer layer is formed by any one of chemical bath deposition (CBD), electrodeposition, covaporation, sputtering, atomic layer epitaxy, atomic layer deposition, chemical vapor deposition (CVD), metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), spray pyrolysis, ILGAR (ion layer gas reaction), and pulsed laser deposition.

15 . The method of manufacturing a solar cell according to claim 11 , wherein in the patterning of the first electrode and the buffer layer, one face of the first electrode opposed to the buffer layer has a saw-toothed pattern including a first electrode protrusion portion, a first electrode depression portion, and a connection portion electrically connecting the first electrode protrusion portion and the first electrode depression portion,
wherein the first electrode protrusion portion is inserted to a depression portion of the buffer layer and is disposed separately at a predetermined space, and wherein a protrusion portion of the buffer layer is inserted into the first electrode depression portion and is disposed separately at a predetermined space.

16 . The method of manufacturing a solar cell according to claim 11 , wherein the patterning of the first electrode, the buffer layer, or the second electrode uses a laser scribing process.

17 . The method of manufacturing a solar cell according to claim 11 , wherein the light absorption layer includes any one selected from a CIS/CIGS-based compound group including Cu—In—Se, Cu—In—S, Cu—Ga—S, Cu—Ga—Se, Cu—In—Ga—Se, Cu—In—Ga—Se—(S,Se), Cu—In—Al—Ga—(S,Se), and Cu—In—Al—Ga—Se—S, and
wherein the light absorption layer is formed by any one method of coevaporation, sputtering, electrodeposition, metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), electrodeposition, screen printing, and particle deposition.

18 . The method of manufacturing a solar cell according to claim 11 , further comprising a step of forming a reflection preventing film on the light absorption layer after the (vi) step of forming the light absorption layer.

19 . The method of manufacturing a solar cell according to claim 18 , wherein the step of forming the reflection preventing film includes:
(a) a step of forming a first reflection preventing layer with Al 2 O 3 by ALD (atomic layer deposition) using Al(CH 3 ) 3 and O 3 as reaction gas on the light absorption layer; and (b) a step of forming a film by thermal evaporator using MgF 2 pellet on the first ref

Assignees

• Korea Energy Research Inst

Inventors

• Eo Young Joo
• Cho Ara
• Cho Jun Sik
• Park Joo Hyung
• Yoon Kyung Hoon
• Ahn Se Jin
• Gwak Ji Hye
• Yun Jae Ho
• Shin Kee Shik
• Ahn Seoung Kyu
• You Jin Su
• Park Sang Hyun

Classifications

• H10F77/707

  of the substrates or of layers on substrates, e.g. textured ITO layer on a glass substrate · CPC title

• H10F77/315

  the coatings being antireflective or having enhancing optical properties · CPC title

• H10F77/311

  for photovoltaic cells · CPC title

• H10F77/251

  comprising zinc oxide [ZnO] · CPC title

• H10F77/244

  made of transparent conductive layers, e.g. transparent conductive oxide [TCO] layers · CPC title