# US 10,121,925 B2 · Thin film photovoltaic devices with microlens arrays

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- Number: US 10,121,925 B2
- Document ID: US10121925B2
- Status: Granted
- Kind: B2
- Application number: 13/704,651
- Filed: 2011-06-17
- Published: 2013-04-18
- Granted: 2018-11-06
- Earliest claimed: 2010-06-18
- Assignees: University of Florida Research Foundation, Inc.
- Applicants: Jiangeng Xue; Jason David Myers; Sang-Hyun Eom
- Inventors: Jiangeng Xue; Jason David Myers; Sang-Hyun Eom
- Web page: https://patentgrep.com/patent/US10121925B2

## CPC

- H10F 77/484: {Refractive light-concentrating means, e.g. lenses}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- G02B 3/0031: {Replication or moulding, e.g. hot embossing, UV-casting, injection moulding}
- G02B 3/0043: {Inhomogeneous or irregular arrays, e.g. varying shape, size, height}
- G02B 5/045: {Prism arrays}
- H10F 77/169: Thin semiconductor films on metallic or insulating substrates
- H10F 77/1692: {the films including only Group IV materials}
- H10F 77/1694: {the films including Group I-III-VI materials, e.g. CIS or CIGS}
- H10F 77/1696: {the films including Group II-VI materials, e.g. CdTe or CdS}
- H10F 77/315: {the coatings being antireflective or having enhancing optical properties}
- H10F 77/413: {directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42)}
- H10F 77/42: directly associated or integrated with photovoltaic cells, e.g. light-reflecting means or light-concentrating means
- H10K 30/35: comprising inorganic nanostructures, e.g. CdSe nanoparticles
- H10K 30/87: Light-trapping means
- H02S 40/22: Light-reflecting or light-concentrating means (directly associated with the PV cell or integrated with the PV cell H10F77/42)
- H10K 30/50: Photovoltaic [PV] devices
- H10K 85/113: {Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene}
- H10K 85/211: {Fullerenes, e.g. C60}
- H10K 85/215: {comprising substituents, e.g. PCBM}
- H10K 85/311: {Phthalocyanine}
- Y02E 10/52: PV systems with concentrators
- Y02E 10/541: CuInSe2 material PV cells
- Y02E 10/549: Organic PV cells
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- H02S: GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES (obtaining electrical energy from radioactive sources G21H1/12; light sensitive inorganic semiconductor devices H10F; light sensitive organic semiconductor devices H10K30/00; thermoelectric devices H10N10/00; pyroelectric devices H10N15/00)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Textured transparent layers are formed on the incident light receiving surface of thin film solar cells to increase their efficiency by altering the incident light path and capturing a portion of the light reflected at the MLA. The textured transparent layer is an array of lenses of micrometer proportions such as hemispheres, hemi-ellipsoids, partial-spheres, partial-ellipsoids, cones, pyramids, prisms, half cylinders, or combinations thereof. A method of forming the textured transparent layer to the light incident surface of the solar cell is by forming an array of lenses from a photocurable resin and its subsequent curing. The photocurable resin can be applied by inkjet printing or can be applied by roll to roll imprinting or stamping with a mold.

## Claims

### Claim 1

A thin film solar cell, comprising:
a transparent microlens array (MLA) layer;
a transparent substrate including an upper surface and a lower surface opposite the upper surface, the upper surface being an essentially flat transparent light receiving surface;
a transparent electrode directly contacting the lower surface of the transparent substrate;
an active layer; and
a distal reflective electrode;
wherein the MLA layer comprises an array of lenses comprising a multiplicity of hemisphere lenses of equal or different sizes, a lower flat surface of the array of lenses directly contacts the essentially flat transparent light receiving surface of the transparent substrate;
wherein at least 60% of the essentially flat transparent light receiving surface is occupied by the array of lenses;
wherein the transparent electrode, the active layer, and the distal reflective electrode are continuous essentially flat layers;
wherein the diameter of each of the multiplicity of hemisphere lenses of the array of lenses is less than the thickness of the transparent substrate; and
wherein the MLA layer is configured not to focus light to a particular spot or area in the thin film solar cell.

### Claim 2 (depends on 1)

The thin film solar cell of claim 1, wherein each lens of the array of lenses are of equal diameter.

### Claim 3 (depends on 1)

The thin film solar cell of claim 1, wherein the hemisphere lenses are of a plurality of diameter.

### Claim 4 (depends on 1)

The thin film solar cell of claim 1, wherein the MLA layer comprises a photo-cured resin or a thermal-cured resin.

### Claim 5 (depends on 1)

The thin film solar cell of claim 1, wherein the MLA layer comprises TiO2 nanoparticles, ZrO2 nanoparticles, CeO2 nanoparticles, lead zirconate tinate (PZT) nanoparticles, or any combination thereof.

### Claim 6 (depends on 1)

The thin film solar cell of claim 1, wherein the active layer comprises an inorganic semiconducting thin film that is amorphous, nanocrystalline, microcrystalline, or polycrystalline and said inorganic semiconducting thin film comprises silicon, silicon germanium, CdTe, CdS, GaAs, Cu2S, CuInS2, Cu(InxGa1-x)Se2, or CuZnSn(S,Se).

### Claim 7 (depends on 1)

The thin film solar cell of claim 1, wherein the active layer comprises organic semiconducting thin films based on organic compounds or conjugated polymers.

### Claim 8 (depends on 1)

The thin film solar cell of claim 1, wherein the active layer comprises hybrid organic-inorganic semiconducting thin films containing inorganic nanoparticles and conjugated polymers or molecules.

### Claim 9 (depends on 1)

The thin film solar cell of claim 1, wherein the distal reflective electrode comprises a reflective metal.

### Claim 10 (depends on 1)

The thin film solar cell of claim 1, wherein the transparent substrate comprises transparent surface is of a substrate comprising glass, plastic or thermoset resin.

### Claim 11 (depends on 10)

The thin film solar cell of claim 10, wherein the MLA layer and the transparent substrate are the same material.

### Claim 12 (depends on 1)

The thin film solar cell of claim 1, wherein the transparent electrode comprises tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), gallium doped zinc oxide (GZO), graphene, carbon nanotubes, conductive polymers, metal oxide/metal/metal oxide multi-layers, metallic gratings, or metallic nanowire networks.