F R A U N H O F E R I N S T I T U T E F O R S O l A R E N E R g y S y S T E m S I S E

III-V-EpItaxy and Solar CEllS

Fraunhofer ISE has long time experience in

developing highest performance solar cells

made from III-V compound semiconductors.

We use materials made from the 3rd and 5th

column of the periodic table such as GaAs

or GaInP to develop multi-junction devices.

Our solar cells reach record efficiencies up

to 46.0 % under sunlight concentrated

508 times. We offer industry and research

partners comprehensive services to enhance

their products.

III-V Devices

Our unique epitaxy knowledge enables

lattice-mismatched growth on Ge and Si

and we use wafer bonding to combine

materials on GaAs with InP, GaSb, Ge and

Si. This opens unique opportunities for a

variety of next generation high efficiency

PV cells, as well as other optoelectronic

products. Our expertise ranges from

theoretical simulation to material analysis,

structure design, device processing, charac-

terization, packaging and reliability testing.

CPV-modules

In concentrating photovoltaics, we follow

an integrated approach, developing both

high-efficiency solar cells and concentrator

photovoltaic modules and systems. The lens

based FLATCON® concentrator module was

initially developed in close collaboration

with scientists at the Ioffe Institute in

St. Petersburg and commercialized in 2005

by the spin-off company Concentrix Solar.

Today pilot manufacturing and next gene-

ration product development are available in

the institute.

Calibration Services

The department operates a unique calibra-

tion laboratory for multi-junction solar cells

and concentrator modules. We measure

devices with up to 6 junctions under a vari-

ety of spectral and temperature conditions.

Record results are reported in the efficiency

tables published by »Progress in Photo-

voltaics«. We further develop advanced

characterization tools for the industry.

1 Wafer with hundreds of

concentrator cells.

2 Epitaxy reactor for III-V compounds.

(Photo: Thomas Klink)

3 High-concentration photovoltaic

module.

Fraunhofer Institute for

Solar Energy Systems ISE

Heidenhofstr. 2

79110 Freiburg

Germany

III-V and Concentrator Photovoltaics –

III-V Epitaxy and Solar Cells

Dr Frank Dimroth

Phone +49 761 4588-5258

cpv.III-V@ise.fraunhofer.de

www.III-V.de

www.ise.fraunhofer.de

09-830-16

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Research Awards

nBecquerel Prize, Fraunhofer Prize,

Louis D. Science Award, EARTO Innovation

Award, French-German Economy Award,

World Technology Award

Selected Publications

n Steiner, M., et al., 43% Sunlight to

Electricity Conversion Efficiency Using CPV.

IEEE Journal of Photovoltaics, 2016. 6(4):

p. 1020-1024.

n Dimroth, F., et al., Four-Junction Wafer-

Bonded Concentrator Solar Cells. IEEE

Journal of Photovoltaics, 2016. 6(1):

p. 343-349.

n Essig, S., et al., Wafer-bonded GaInP/

GaAs//Si solar cells with 30% efficiency

under concentrated sunlight. IEEE Journal

of Photovoltaics, 2015. 5(3): p. 977-81.

n Steiner, M., et al., FLATCON CPV

module with 36.7% efficiency equipped

with four-junction solar cells. Progress in

Photovoltaics: Research and Applications,

2014. 23(10): p. 1323 - 1329.

n Philipps, S. and A. Bett, III-V Multi-

junction solar cells and concentrating

photovoltaic (CPV) systems. Advanced

Optical Technologies, 2014: p. 469-78.

These and other publications:

https://www.ise.fraunhofer.de/en/

publications/1-02

4 Wafer-bonder for III-V silicon integration.

5 Device processing in clean-room.

6 CPV module IV-measurement. (Photo: Mahler)

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Our Expertise

Fraunhofer ISE provides comprehensive

expertise on III-V devices and CPV modules:

n metal-organic vapor phase epitaxy of

high efficiency III-V solar cells

n simulation of semiconductor devices

n III-V material characterization

n direct wafer bonding of III-V

compounds, Ge, Si and sapphire

n batch processing of III-V solar cells on

substrates with up to 150 mm diameter

n optimization of contact grid structures

and anti-reflection coatings

n laser power converters and thermo-

photovoltaic cells

n measurement of multi-junction solar

cells under various spectral conditions

n accelerated aging procedures for con-

centrator cells and module components

n thermal simulation of CPV modules

n packaging technologies for solar cell

assemblies, dense arrays and compact

receivers

n high efficiency CPV modules based on

Fresnel lenses or mirrors

n in- and outdoor characterization of

CPV modules

Advanced Research Topics

New fields of research include large concen-

trator systems delivering both electric and

thermal power. Water desalination and so-

lar cooling are developed as applications for

the solar heat. We engineer the dense array

photovoltaic receiver – compact concentra-

tor module – to achieve high performance

at concentration factors of 800-1200 and

on areas exceeding 100 cm2. Our tandem

MIM (Monolithic Interconnected Module)

solar cells deliver high voltages and low

series resistance and our MWT (Metal

Wrap Through) cells allow full backside

integration and interconnection. These solar

cells reach electric conversion efficiencies

of 27 % and our compact concentrator

modules may reach up to 70% system

efficiency including heat.

HyCon® is a unique concentrator module

which converts sunlight into hydrogen

produced by the electrolysis of water. This

innovative approach was invented by our

scientists in 2001 and has by now demons-

trated conversion efficiencies of sunlight to

hydrogen up to 30 %. No other technology

has shown similar performance.

Our III-V multi-junction solar cells on silicon

reach >30 % efficiency under standard

AM1.5g conditions and lead the way

to high performance flat-plate photovol-

taics. We innovate solar technology by

our unique expertise in high efficiency

photovoltaics.

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