SOLAR CELL AND SOLAR CELL MANUFACTURING METHOD

• US 20110290310A1
• Filed: 05/26/2011
• Published: 12/01/2011
• Est. Priority Date: 05/27/2010
• Status: Abandoned Application

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Hosoya, Youichi, KURAMACHI, Teruhiko, Tanaka, Atsushi, Kikuchi, Makoto, Hama, Takeshi
• Application Number:
  US13/116,404
• Publication Number:
  US 20110290310A1
• Time in Patent Office: Days
• US Class Current: 136/255
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H01L 31/035218 the quantum structure being quantum dots
• CPC Class Codes: H01L 31/075 the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells

Abstract

A solar cell capable of restricting carrier loss and yields higher energy conversion efficiency than was conventionally possible and a method of producing a solar cell enabling formation of a light absorbing layer containing quantum dots through a low-temperature process using a coating or printing method requiring no vacuum equipment or complicated apparatuses. The solar cell includes a light absorbing layer containing quantum dots in a matrix layer, and the light absorbing layer is connected to an N-type semiconductor layer on one side and to a P-type semiconductor layer on the other side. In the light absorbing layer, the quantum dots are made of nanocrystalline semiconductor and arranged 3-dimensionally uniformly enough and spaced regularly so that a plurality of wave functions lie on one another between adjacent quantum dots to form intermediate bands. The matrix layer is formed of amorphous IGZO.

Claims

1. A solar cell comprising:

an N-type semiconductor layer on one side of a light absorbing layer containing quantum dots in a matrix layer and a P-type semiconductor layer on the other side of the light absorbing layer,

wherein the quantum dots are made of nanocrystalline semiconductor, the quantum dots being arranged 3-dimensionally uniformly enough and spaced regularly so that a plurality of wave functions lie on one another between adjacent quantum dots to form intermediate bands, and

wherein the matrix layer is formed of amorphous IGZO.

2. The solar cell according to claim 1, wherein ε

_FA>

ε

_FB holds, where ε

_FA is a magnitude of energy from a conduction band to a Fermi level of the matrix layer, and ε

_FB is a magnitude of energy from a conduction band to a Fermi level of the N-type semiconductor layer.

3. The solar cell according to claim 1, wherein the matrix layer has a bandgap of 3.2 eV to 3.8 eV.

4. The solar cell according to claim 1, wherein the amorphous IGZO has a composition expressed as In_2-xGa_xO₃ (ZnO)_m, where 0.5<

x<

1.8 and 0.5≦

m≦

3.

5. The solar cell according to claim 1, wherein the quantum dots have a bandgap of 0.4 eV to 1.2 eV in a bulk state.

6. The solar cell according to claim 5, wherein the quantum dots are formed of Si, Si alloy, Ge, SiGe, InN, InAs, InSb, PbS, PbSe, or PbTe.

7. The solar cell according to claim 6, wherein the Si alloy is FeSi₂, Mg₂Si, or CrSi₂.

8. The solar cell according to claim 1, wherein the quantum dots have a mean diameter of 2 nm to 12 nm.

9. The solar cell according to claim 1, wherein the quantum dots have a variation in particle diameter of plus or minus 20% or less.

10. A method of manufacturing a solar cell comprising an N-type semiconductor layer on one side of a light absorbing layer containing quantum dots in a matrix layer formed of amorphous IGZO and a P-type semiconductor layer on the other side of the light absorbing layer, the P-type semiconductor layer having a first electrode layer on a side opposite from the light absorbing layer, the N-type semiconductor layer having a second electrode layer on a side opposite from the light absorbing layer,

wherein a step of forming the light absorbing layer comprises:

a step of applying or printing a mixture of a first IGZO precursor in a state of liquid and a particle dispersed solution in which particles forming the quantum dots are dispersed in a solvent onto the N-type semiconductor layer or the P-type semiconductor layer and

a heat treatment step to vaporize the solvent contained in the mixture.

11. The method of manufacturing a solar cell according to claim 10, wherein a step of forming the N-type semiconductor layer comprises:

a step of applying or printing a second IGZO precursor in a state of liquid containing a solvent onto the light absorbing layer or the second electrode layer, and

a heating step to vaporize the solvent contained in the second IGZO precursor.

12. The method of manufacturing a solar cell according to claim 10, wherein a step of forming the P-type semiconductor layer comprises:

a step of applying or printing a precursor solution or a crystalline nanoparticle dispersed solution onto the light absorbing layer or the first electrode layer, and

a step of vaporizing the solvent in the precursor solution or the solvent in the crystalline nanoparticle dispersed solution.

13. The method of manufacturing a solar cell according to claim 12, wherein the precursor solution contains a CuAlO₂ precursor.

14. The method of manufacturing a solar cell according to claim 12, wherein the crystalline nanoparticle dispersed solution contains a CuGaS₂ particle dispersion.

15. The method of manufacturing a solar cell according to claim 10, comprising a passivation step for preventing occurrence of defects at interfaces between the quantum dots and the matrix layer and in the matrix layer after the light absorbing layer is formed.

16. The method of manufacturing a solar cell according to claim 15, wherein the passivation step comprises either a step of immersing the light absorbing layer in an ammonium sulfide solution or a cyanide solution or a step of heating the light absorbing layer in the presence of hydrogen gas, hydrogen fluoride gas, hydrogen bromide gas, or hydrogen phosphide gas.