High performance, high bandgap, lattice-mismatched, GaInP solar cells

• US 9,484,480 B2
• Filed: 06/24/2014
• Issued: 11/01/2016
• Est. Priority Date: 12/30/2004
• Status: Active Grant

• Current Assignee: Alliance For Sustainable Energy LLC
• Original Assignee: Alliance For Sustainable Energy LLC
• Inventors: Wanlass, Mark W, Steiner, Myles A, Carapella, Jeffrey J
• Primary Examiner(s): Pillay, Devina
• Application Number:
  US14/313,720
• Publication Number:
  US 20150020875A1
• Time in Patent Office: 861 Days
• Field of Search: 136/255
• US Class Current: 1/1
• CPC Class Codes: H01L 31/02168 the coatings being antireflective or having enhancing optical properties for the solar cells
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/032 including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
• CPC Class Codes: H01L 31/065 the potential barriers being only of the graded gap type
• CPC Class Codes: H01L 31/068 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
• CPC Class Codes: H01L 31/06875 inverted grown metamorphic [IMM] multiple junction solar cells, e.g. III-V compounds inverted metamorphic multi-junction cells
• CPC Class Codes: H01L 31/0693 the devices including, apart from doping material or other impurities, only AIIIBV compounds, e.g. GaAs or InP solar cells
• CPC Class Codes: H01L 31/1844 comprising ternary or quaternary compounds, e.g. Ga Al As, In Ga As P
• CPC Class Codes: H01L 31/1892 methods involving the use of temporary, removable substrates
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

High performance, high bandgap, lattice-mismatched, photovoltaic cells (10), both transparent and non-transparent to sub-bandgap light, are provided as devices for use alone or in combination with other cells in split spectrum apparatus or other applications.

Claims

1. A photovoltaic converter comprising:

a photovoltaic cell comprising GaInP having a bandgap greater than about 1.9 eV, wherein the photovoltaic cell has a junction and is lattice-mismatched to a parent substrate; and

a graded layer positioned between the parent substrate and the photovoltaic cell, wherein;

the parent substrate comprises GaAs,

the graded layer has a lattice constant that changes from a first lattice constant in a first portion closest to the parent substrate to a second lattice constant in a second portion closest to the photovoltaic cell, such that the second lattice constant matches a relaxed lattice constant of the photovoltaic cell,

the photovoltaic cell includes an emitter on a front side of the junction and a base on a back side of the junction, and

the photovoltaic converter further comprises;

(i) a double heterostructure comprising a back surface confinement layer on the base and a passivation/window layer on the emitter;

(ii) a front contact layer comprising doped GaAsP between a metal grid and the passivation/window layer;

(iii) an anti-reflection coating on the passivation/window layer between contacts of the front contact layer; and

(iv) a back contact layer comprising doped GaAsP on the back surface confinement layer.

2. The photovoltaic converter of claim 1, further comprising a transparent handle mounted adjacent to the front contact layer.

3. A photovoltaic converter comprising:

a photovoltaic cell comprising GaInP having a bandgap greater than about 1.9 eV, wherein the photovoltaic cell has a junction and is lattice-mismatched to a GaAs parent substrate; and

a graded layer positioned between the parent substrate and the photovoltaic cell, wherein;

the graded layer comprises GaAs_1-xP_x, and “

x”

increases in discrete incremental steps from a first value in a first portion closest to the parent substrate to a second value in a second portion closest to the photovoltaic cell until the proportions of As and P are such that the GaAs_1-xP_x in the second portion has a lattice constant that matches a relaxed lattice constant of the photovoltaic cell,

the graded layer comprises 6 to 10 steps of GaAs_1-xP_x,

each step is between about 1.0 μ

m and about 2.2 μ

m thick,

the P content increases and the As content correspondingly decreases from the first portion to the second portion by about 4 percent to about 6 percent per step, and

a last step in the second portion comprises between about 30 percent and 44 about percent P.

4. The photovoltaic converter of claim 3, wherein:

the photovoltaic cell includes a base on a back side of the junction and an emitter on a front side of the junction, and

the photovoltaic converter further comprises;

(i) a double heterostructure comprising a back surface confinement layer between the graded layer and the base, and a passivation/window layer on the emitter;

(ii) a contact layer comprising doped GaAsP between a metal grid and the passivation/window layer;

(iii) an anti-reflection coating on the passivation/window layer between contacts of the contact layer; and

(iv) an electrically conductive back contact on a back side of the parent substrate.

5. A photovoltaic converter comprising:

a photovoltaic cell comprising GaInP having a bandgap greater than about 1.9 eV, wherein the photovoltaic cell has a junction and is lattice-mismatched to a GaAs parent substrate; and

a graded layer positioned between the parent substrate and the photovoltaic cell, wherein;

the graded layer comprises GaAs_1-xP_x, and “

x”

increases from a first value in a first portion closest to the parent substrate to a second value in a second portion closest to the photovoltaic cell until the proportions of As and P are such that the GaAs_1-xP_x in the second portion has a lattice constant that matches a relaxed lattice constant of the photovoltaic cell,

the photovoltaic cell includes an emitter on a front side of the junction and a base on a back side of the junction, and

the photovoltaic converter further comprises;

(i) a double heterostructure comprising a back surface confinement layer on the base and a passivation/window layer on the emitter;

(ii) a front contact layer comprising doped GaAsP between a metal grid and the passivation/window layer;

(iii) an anti-reflection coating on the passivation/window layer between contacts of the front contact layer; and

(iv) a back contact layer comprising doped GaAsP on the back surface confinement layer.

6. The photovoltaic converter of claim 5, further comprising a transparent handle mounted adjacent to the front contact layer.