Front sheet of solar cell, method of manufacturing the same and photovoltaic module comprising the same

Patent metadata

Field	Value
Publication number	US-9117952-B2
Application number	US-201213371069-A
Country	US
Kind code	B2
Filing date	Feb 10, 2012
Priority date	Feb 10, 2011
Publication date	Aug 25, 2015
Grant date	Aug 25, 2015

Abstract

A front sheet of solar cell, a method of manufacturing the same and a photovoltaic module are provided. The front sheet of solar cell can effectively block infrared rays (IRs) by forming an IR blocking layer including a cholesteric liquid crystal (CLC) material on a substrate. Thus, an increase in temperature of a cell can be suppressed so that the power generation efficiency of the cell can be improved. Also, the multi-layered sheet can be configured so that a UV blocking layer including a fluorine-based polymer and a wavelength conversion material can be formed on the IR blocking layer. Thus, wavelengths of a UV region can be converted into wavelengths of a VR region so that the power generation efficiency of the cell can be improved, and discoloration and deformation caused by UVs can be prevented so that the weather resistance can be improved.

First claim

What is claimed is:

1. A front sheet of a solar cell comprising:
a substrate;
an infrared ray (IR) blocking layer formed on one surface of the substrate and including a cholesteric liquid crystal (CLC) material; and
an ultraviolet ray (UV) blocking layer formed on the IR blocking layer and including a fluorine-based polymer and a wavelength conversion material, wherein the wavelength conversion material converts light in the UV region into light in the visible region, and wherein the IR blocking layer blocks IRs having a wavelength of 1,000 nm to 2,650 nm,
wherein the CLC material comprises 98 parts by weight to 99 parts by weight of the nematic liquid crystal compound; and 1 part by weight to 2 parts by weight of the chiral compound; and
wherein the CLC material selectively reflects light having a selective reflection center wavelength of 1,000 nm to 2,650 nm.

2. The front sheet of a solar cell of claim 1 , wherein the substrate is a polyethylene terephthalate (PET) film, a poly(meth)acryl film, a polyvinylidene chloride (PVDC) film or a polyvinyl chloride (PVC) film.

3. The front sheet of a solar cell of claim 1 , wherein the CLC material comprises a compound represented by the following Formula 1 in a cross-linked or polymerized form: Formula 1

wherein A is a single bond, —COO— or —OCO—, R 1 to R 10 each independently represent hydrogen, a halogen, an alkyl group, an alkoxy group, a cyano group, a nitro group, —O-Q-P or a substituent represented by the following Formula 2, provided that at least one of R 1 to R 10 is —O-Q-P or a substituent of the following Formula 2, Q is an alkylene group or an alkylidene group, and P is an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a (meth)acryloyl group, an acryloyloxy group or a (meth)acryloyloxy group: Formula 2

wherein B is a single bond, —COO— or —OCO—, R 11 to R 15 each independently represent hydrogen, a halogen, an alkyl group, an alkoxy group, a cyano group, a nitro group or —O-Q-P, provided that at least one of R 11 to R 15 is —O-Q-P, Q is an alkylene group or an alkylidene group, and P is an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a (meth)acryloyl group, an acryloyloxy group or a (meth)acryloyloxy group.

4. The front sheet of a solar cell of claim 1 , wherein the IR blocking layer has a concentration gradient of the chiral compound formed in a vertical direction thereof, and a reflection wavelength width of 200 nm or more.

5. The front sheet of a solar cell of claim 1 , wherein the IR blocking layer has a single-layer structure or a multi-layered structure of two or more layers.

6. The front sheet of a solar cell of claim 5 , wherein the IR blocking layer comprises different CLC materials in each layer when the IR blocking layer has a multi-layered structure of two or more layers.

7. The front sheet of a solar cell of claim 1 , wherein the IR blocking layer further comprises a heat stabilizer or a UV stabilizer.

8. The front sheet of a solar cell of claim 1 , wherein the IR blocking layer has a thickness of 1 μm to 50 μm.

9. The front sheet of a solar cell of claim 1 , wherein the fluorine-based polymer is a homopolymer, copolymer or a mixture thereof including at least one monomer selected from the group consisting of vinylidene fluoride (VDF), vinyl fluoride (VF), tetrafluoroethylene (TFE) hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), trifluoroethylene, hexafluoroisobutylene, perfluorobutyl ethylene, perfluoro (methylvinylether) (PMVE), perfluoro (ethylvinylether) (PEVE), perfluoro (propylvinylether) (PPVE), perfluoro(hexylvinylether) (PHVE), perfluoro-2,2-dimethyl-1,3-dioxol (PDD) and perfluoro-2-methylene-4-methyl-1,3-dioxolane (PMD) in a polymerized form.

10. The front sheet of a solar cell of claim 1 , wherein the wavelength conversion material is a fluorescent material that absorbs a short wavelength region of light to emit a long wavelength region of light.

11. The front sheet of a solar cell of claim 10 , wherein the short wavelength region is in a range of 300 nm to 400 nm, and the long wavelength region is in a range of 400 nm to 1000 nm.

12. The front sheet of a solar cell of claim 10 , wherein the fluorescent material includes a rare earth element as impurities and has a transmittance at a visible ray (VR) region of 85% or more.

13. The front sheet of a solar cell of claim 12 , wherein the fluorescent material is at least one selected from the group consisting of La 2 O 2 S:Eu, (Ba,Sr) 2 SiO 4 :Eu and Sr 5 (PO 4 ) 3 Cl:Eu.

14. The front sheet of a solar cell of claim 10 , wherein the fluorescent material has a primary average particle size of 1 nm to 100 nm.

15. The front sheet of a solar cell of claim 14 , wherein the UV blocking layer further includes at least one of fine particles selected from the group consisting of zinc oxide, titanium oxide, cerium oxide, zirconium oxide and iron oxide.

16. The front sheet of a solar cell of claim 1 , wherein the UV blocking layer has a thickness of 1 μm to 100 μm.

17. A photovoltaic module comprising the front sheet of a solar cell according to claim 1 .

Assignees

• Kim Hyun Cheol
• Park Moon Soo
• Lee Dae Hee
• Kwon Yoon Kyung
• Ko Hyun Seong
• Lg Chemical Ltd

Inventors

• Kim Hyun Cheol
• Park Moon Soo
• Lee Dae Hee
• Kwon Yoon Kyung
• Ko Hyun Seong

Classifications

• H10F77/45 Primary

  Wavelength conversion means, e.g. by using luminescent material, fluorescent concentrators or up-conversion arrangements · CPC title

• H10F77/42

  directly associated or integrated with photovoltaic cells, e.g. light-reflecting means or light-concentrating means · CPC title

• H10F19/804

  Materials of encapsulations · CPC title

• H10F19/85

  Protective back sheets · CPC title

• H10F77/334 Primary

  for shielding light, e.g. light blocking layers or cold shields for infrared detectors · CPC title