Photon Management Enables High Efficiency Photovoltaics

©Fraunhofer ISE/Foto: Guido Kirsch

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Photon Management Enables High Efficiency Photovoltaics

Henning Helmers

Fraunhofer Institute for Solar Energy Systems ISE

4th Fraunhofer Symposium on „Digital Photonics made in Germany“

Tokyo, 09.10.2019

www.ise.fraunhofer.de

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December 12, 2015Paris, France

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1.5e18 kWh/year

>10‘000 times the worldenergy consumption

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Silicon-based Photovoltaics Solarsiedlung, Stadtteil Vauban, Freiburg, Germany

Picture: Rolf Disch SolarArchitektur, www.rolfdisch.de

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Silicon-based Photovoltaics: Top 25 Operational Solar PV Plants in Japan

Pictures: https://asia.solar-asset.management/top-25-largest-projects

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Terawatt-scale Photovoltaics: Trajectories and Challenges [1]

Solar capacity is growing exponentially for decades

2018, solar PV capacity additions passed 100 GW mark

Exponential growth rate of solar substantially greater than growth in electricity demand

Request to technology

Further cost reduction

Efficiency increase (=reduced balance of system cost)

[1] NM Haegel, R Margolis, T Buonassisi, D Feldman, A Froitzheim, R Garabedian, M Green, S Glunz, HM Henning, B Holder, I Kaizuka, B Kroposki, K Matsubara, S Niki, K Sakurai, RA Schindler, W Tumas, ER Weber, G Wilson, M Woodhouse, S Kurtz, Science 356(6334), 2017. DOI: 10.1126/science.aal1288

[2] REN21. Renewables 2019 Global Status Report, 2019. ISBN 978-3-9818911-7-1

2018[2]

Glo

bal

po

wer

pla

nts

cap

aci

ty[T

W]

or

ad

dit

ion

s[T

W/y

ear]

Total

Total additions

Solar

Solar additions

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[#] Yoshikawa, et al., Nature Energy 2, 2017.[§] Polman, et al., Science 352, 2016 (latest values: www.lmpv.nl/SQ).

Silicon Based Solar Cells: State of the Art

Si

Si single-junctionsolar cell

Kaneka IBC record cell [#]=26.7%

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500 1000 1500 2000 25000.00.20.40.60.81.01.21.41.6

Spec

tral i

rradi

ance

[W/m

²/nm

]Wavelength [nm]

Solar spectrum Si

High-efficiency PhotovoltaicsHow to Make Better Use of the Broad Band Solar Spectrum?

Detailed balance calculation in the Shockley-Queisser limit [†]

Si

Si single-junctionsolar cell

Kaneka IBC record cell [#]=26.7%

[#] Yoshikawa, et al., Nature Energy 2, 2017.[§] Polman, et al., Science 352, 2016 (latest values: www.lmpv.nl/SQ).[†] Shockley and Queisser, J Appl Phys 32(3), 1961.

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500 1000 1500 2000 25000.00.20.40.60.81.01.21.41.6

Spec

tral i

rradi

ance

[W/m

²/nm

]Wavelength [nm]

Solar spectrum Si

High-efficiency PhotovoltaicsHow to Make Better Use of the Broad Band Solar Spectrum?

[†] Shockley and Queisser, J Appl Phys 32(3), 1961.

Detailed balance calculation in the Shockley-Queisser limit [†]

Si

Si single-junctionsolar cell

X

–

–

–

–

+++

+

EC

EV

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High-efficiency PhotovoltaicsEnabled by Photon Management

Manipulate the spectrum [1,2,3,4]

Adapt the receiver material

[1] Götzberger, Greubel, Appl Phys 14, 1977: Luminescent concentrator[2] Young, Appl Opt 5(6), 1966: Solar-pumped fiber laser[3] Harder and Würfel, Semicond Sci Tech 18, 2003: Thermophotovoltaics[4] Trupke, Green, Würfel, J Appl Phys 92, 2002: Up- and down-conversion of photons

Fondriest Environmental “Solar Radiation and Photosynethically Active Radiation.” Fund Environ Meas. 2014.

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High-efficiency PhotovoltaicsEnabled by Photon Management

Manipulate the spectrum [1,2,3,4]

Solar-pumped fiber laser [2]

Adapt the receiver materialbelow/above

laser threshold

Reusswig, Nechayev, Scherer, Hwang, et al, Scientific Reports 5, 2015.

[1] Götzberger, Greubel, Appl Phys 14, 1977: Luminescent concentrator[2] Young, Appl Opt 5(6), 1966: Solar-pumped fiber laser[3] Harder and Würfel, Semicond Sci Tech 18, 2003: Thermophotovoltaics[4] Trupke, Green, Würfel, J Appl Phys 92, 2002: Up- and down-conversion of photons

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Reusswig, Nechayev, Scherer, Hwang, et al, Scientific Reports 5, 2015.

High-efficiency PhotovoltaicsEnabled by Photon Management

Manipulate the spectrum [1,2,3,4]

Solar-pumped fiber laser [2]

Adapt the receiver materialbelow/above

laser threshold

Yabe, Ohkubo, Uchida, Yoshida, et al, Appl Phys Lett 90, 2007.

[1] Götzberger, Greubel, Appl Phys 14, 1977: Luminescent concentrator[2] Young, Appl Opt 5(6), 1966: Solar-pumped fiber laser[3] Harder and Würfel, Semicond Sci Tech 18, 2003: Thermophotovoltaics[4] Trupke, Green, Würfel, J Appl Phys 92, 2002: Up- and down-conversion of photons

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Photovoltaic Laser Power ConvertersTheoretical Limit

Detailed balance calculation in the Shockley-Queisser limit for a single-junction PV cell

400 600 800 1000 1200 1400 1600 18000

10

20

30

40

50

60

70

80

90

100

Solar cell

Bandgap Eg [eV]

Opt

o-el

ectri

cal c

onve

rsio

n ef

ficie

ncy

[%]

Wavelength [nm]

3 2 1 0.7

[#] Shockley and Queisser, J Appl Phys 32(3), 1961.

[#]

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Photovoltaic Laser Power ConvertersTheoretical Limit

Detailed balance calculation in the Shockley-Queisser limit for a single-junction PV cell

400 600 800 1000 1200 1400 1600 18000

10

20

30

40

50

60

70

80

90

100

100 W/cm²10 W/cm²1 W/cm²

0.1 W/cm²

Solar cell

0.01 W/cm²

Bandgap Eg [eV]

Opt

o-el

ectri

cal c

onve

rsio

n ef

ficie

ncy

[%]

Wavelength [nm]

0.1 W/cm²

Laser powerconverter

3 2 1 0.7

[#] Shockley and Queisser, J Appl Phys 32(3), 1961. [§] Bett, Dimroth, Löckenhoff, Oliva, Schubert, Proc IEEE PVSC, San Diego, 2008.

[#]

[§]

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Photovoltaic Laser Power Converters Photon Management by Bandgap Engineering: III-V Compound Semiconductors

III IV V

5 B 6 C 7 N

13 Al 14 Si 15 P

31 Ga 32 Ge 33 As

49 In 50 Sn 51 Sb

81 Tl 82 Pb 83 Bi 400 800 1200 16000.0

0.2

0.4

0.6

0.8

1.0

1.2

In0.

53G

a 0.4

7As

InG

aAsP

InG

aAsP

Ga 0

.85In

0.15

As

GaA

s

Spec

tral r

espo

nse

[A/W

]

Wavelength [nm]

Ga 0

.50In

0.50

P

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Photovoltaic Laser Power Converters Photon Management by Bandgap Engineering: III-V Compound Semiconductors

III IV V

5 B 6 C 7 N

13 Al 14 Si 15 P

31 Ga 32 Ge 33 As

49 In 50 Sn 51 Sb

81 Tl 82 Pb 83 Bi 400 800 1200 16000.0

0.2

0.4

0.6

0.8

1.0

1.2

In0.

53G

a 0.4

7As

InG

aAsP

InG

aAsP

Ga 0

.85In

0.15

As

GaA

s

Spec

tral r

espo

nse

[A/W

]

Wavelength [nm]

Ga 0

.50In

0.50

P

1550

1310

1064

980

850

808

650

1625

635

830

Common laser wavelengths [nm]

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Photovoltaic Laser Power Converters Light Trapping and Photon Recycling

Cell on substrate: Emitted photons fromthe absorber are lost into the substrate

GaAs substrate

GaAs PV cell

750 800 850 900 95010-3

10-2

10-1

100

Emission spectrumof GaAs

Inte

nsity

[a.u

.]

Wavelength [nm]

1.6 1.5 1.4Energy [eV]

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Photovoltaic Laser Power Converters Light Trapping and Photon Recycling

Cell on substrate: Emitted photons fromthe absorber are lost into the substrate

Back mirror: Light is trapped inside theabsorber increased carrier concentration boost voltage („photon recycling“) [#]

Schilling, et al., IEEE JPV 8(1), 2018.

Miller, et al, IEEE JPV 2(3), 2012.

GaAs substrate

GaAs PV cell

GaAs PV cell

750 800 850 900 95010-3

10-2

10-1

100

Emission spectrumof GaAs

Inte

nsity

[a.u

.]

Wavelength [nm]

1.6 1.5 1.4Energy [eV]

[#] Miller, et al., IEEE JPV 2(3), 2012. | Walker, et al., IEEE JPV 5(6), 2015.

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Photovoltaic Laser Power Converters Light Trapping and Photon Recycling

Cell on substrate: Emitted photons fromthe absorber are lost into the substrate

Back mirror: Light is trapped inside theabsorber increased carrier concentration boost voltage („photon recycling“)

Schilling, et al., IEEE JPV 8(1), 2018.

10-3 10-2 10-1 100

1.01.11.21.356586062646668

V OC [V

]

Tunable laser (860 nm) LaserSim (809 nm) FlashSim (broad band) MuSim (broad band)

860

nm [%

]

Equivalent input power P860nm [W]

67.3%

Ades=0.054 cm²T=25°C

Helmers, Höhn, Lackner, López, et al., Proc OWPT, Yokohama, 2019.

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Power (and Data) by LightOptical Power Transmission – An Enabling Technology

Picture: Christine Daniloff

Wireless power

Explosion protection

Picture: wikipedia/C-Axwel-CC-BY

Galvanic isolation

Picture: Dennis Richardson

Electro-magnetic interference

Picture: St Jude Medical

Lightning protection

Picture: www.cleanandgreenlaw.com Picture: wiki.vag.cc

Weight reduction

Helmers, Lackner, Siefer, Oliva, et al., Proc 32nd EU PVSEC, Munich, 2016.Helmers, Höhn, Lackner, López, et al., Proc OWPT, Yokohama, 2019.

© Fraunhofer ISE© Fraunhofer ISE © Hustvedt/CC-BY-SA-3.0/GFDL

Laser PV cellFree space/

optical fiber

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High-efficiency PhotovoltaicsEnabled by Photon Management

Manipulate the spectrum

Adapt the receiver material

Multi-junction solar cells [1,2]

Fondriest Environmental “Solar Radiation and Photosynethically Active Radiation.” Fund Environ Meas. 2014.

[1] Henry, J Appl Phys 51, 1980.[2] Philipps, Dimroth, Bett, in: McEvoy's Handbook of Photovoltaics, Kalogirou (Ed.), London: Academic Press, 2018.

© Fraunhofer ISE

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500 1000 1500 2000 25000.00.20.40.60.81.01.21.41.6

Spec

tral i

rradi

ance

[W/m

²/nm

]Wavelength [nm]

Solar spectrum Si

High-efficiency PhotovoltaicsHow to Make Better Use of the Broad Band Solar Spectrum?

[#] Shockley and Queisser, J Appl Phys 32(3), 1961.

Detailed balance calculation in the Shockley-Queisser limit [#]

Si

Si single-junctionsolar cell

X

–

–

–

–

+++

+

EC

EV

© Fraunhofer ISE

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FHG-SK: ISE-INTERNAL

500 1000 1500 2000 25000.00.20.40.60.81.01.21.41.6

Spec

tral i

rradi

ance

[W/m

²/nm

]Wavelength [nm]

Solar spectrum Si AlGaAs AlGaInP

High-efficiency PhotovoltaicsHow to Make Better Use of the Broad Band Solar Spectrum?

[#] Shockley and Queisser, J Appl Phys 32(3), 1961.[§] Létay and Bett, Proc 17th EU PVSEC, Munich, Germany, 2001.

Detailed balance calculation in the Shockley-Queisser limit [#,§]

III-V/Si tandemsolar cell

Si

Tunnel diodeAlGaAsTunnel diodeGaInP –

––

++

+

EC

EV

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High-efficiency PhotovoltaicsSi-Tandem Technology Expected

https://itrpv.vdma.org/

1% of 200 GWp

> 6×106 m2/year

Fischer, PV CellTech Conf., 2019. https://itrpv.vdma.org/

Wo

rld

mark

et

share

[%]

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High-efficiency PhotovoltaicsPresent and Future Markets

0.16[#]

sonomotors.com

Solar electricvehicles

Cube sats / high altitude

pseudo satellites

Solar-powered Toyota Prius

[#] Mono PERC cell, high, http://pvinsights.com/ (27.09.2019)

102 103 104 105 107 108 109

1

10

100

0.1So

lar

cell

cost

[€/W

]Market size [m²/a]

Flat panel

Space

Cube sats/HAPS

Automotive

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III-V/Si Tandem Solar CellsFabrication Approach: Wafer Bonding Route

Si

Cariou, Benick, Feldmann, Höhn, et al, Nature Energy 3, 2018.

Tunnel diodeAlGaAsTunnel diodeGaInP

GaAs substrate

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III-V/Si Tandem Solar CellsFabrication Approach: Wafer Bonding Route

Cariou, Benick, Feldmann, Höhn, et al, Nature Energy 3, 2018.

Si

Tunnel diodeAlGaAsTunnel diodeGaInP

GaAs substrate

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III-V/Si Tandem Solar Cellswith Rear-side Photonic Grating

Photonic light trapping realized bynanoimprint lithography

Boost in photo current of Si subcell(indirect semiconductor absorber)

Si

Tunnel diodeAlGaAsTunnel diodeGaInP

Ag

p+ poly-Si

Resist

1 µm

Cariou, Benick, Feldmann, Höhn, et al, Nature Energy 3, 2018.

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III-V/Si Tandem Solar Cellswith Rear-side Photonic Grating

Photonic light trapping realized bynanoimprint lithography

Boost in photo current of Si subcell(indirect semiconductor absorber)

Cariou, Benick, Feldmann, Höhn, et al, Nature Energy 3, 2018.Fraunhofer ISE, press release #22, 28.09.2019.

Si

Tunnel diodeAlGaAsTunnel diodeGaInP

Ag

p+ poly-Si

Resist

1 µm 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50

2

4

6

8

10

12

14

Cur

rent

den

sity

[mA/

cm²]

Voltage [V]

rear-side: planar photonic [%]: 32.3 34.1

AM1.5g, 1000 W/m², T=25°C, A=3.987 cm²

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Bio-inspired Photonic Structures for Integrated PhotovoltaicsMorpho-Color®

Idea:

Morpho butterfly: bright, angle independent color originated from a 3D photonic structure

Realization:

Morpho effect reproduced by Bragg stack on a structured substrate

Potyrailo et al, Nat Comm 6, 2015.

Solar cell

Laminate

Bragg stack

Module glass

Höhn, Kroyer, Bläsi, Kuhn, Hinsch, Patent: WO/2018/154045.

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Bio-inspired Photonic Structures for Integrated Photovoltaics: Morpho-Color® PV Modules for Building Integration

Narrow band reflection:

Bright color appearance

Only 7% relative efficiency reduction

Various colors possible

Only module glass is modified

Standard solar cells and lamination processes can be used

Demonstrator modules: 1.09 x 1.12 m2

Höhn, Kroyer, Bläsi, Kuhn, Hinsch, Patent: WO/2018/154045.

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Bio-inspired Photonic Structures for Integrated Photovoltaics: Morpho-Color® PV Modules for Vehicle Integration

Fraunhofer ISE, press release #23, 02.09.2019

Frankfurt Motor Show (IAA), 2019

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Photon Management Enables High Efficiency PhotovoltaicsSummary

Power-by-Light

Bandgap engineering for PV laser power converters

Efficiency of 860nm=67.3% enabled by photon recycling

Tandem solar cells

Photonic rear-side gratings enable light trapping

III-V/Si tandem solar cell with 34.1% efficiency demonstrated

Photonic structures enable invisible photovoltaicse.g. for building and vehicle integration

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Acknowledgements

Sincere thanks to

all sponsors for financial support

all partners

all co-workers at Fraunhofer ISE

Photo: Dirk Mahler

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Thank you for your Attention!

Fraunhofer Institute for Solar Energy Systems ISE

Dr. Henning Helmers, Deputy Head of Department “III-V Photovoltaics and Concentrator Technology”

www.ise.fraunhofer.de | www.III-V.de | s.fhg.de/profile-h-helmers

henning.helmers@ise.fraunhofer.de