This document is a presentation on nanotechnology for efficient solar energy conversion. It begins by quantifying the challenge of photovoltaic solar energy in achieving competitive generation costs below 5 cents per kWh and system prices below 1 euro per watt peak. It then discusses current commercial solar cell and module technologies, as well as concepts and technologies in labs and pilot production aiming for very high efficiencies and very low costs. The presentation notes how nanotechnology can be used to go beyond current performance and cost limits, for example through advanced light management, multi-junction cells, and spectrum shaping using quantum dots. It concludes by outlining the commercialization outlook, with projections for module efficiencies reaching 20-50% and system prices below 1

1. www.ecn.nl
Where very small meets very large:
nanotechnology for efficient solar energy
conversion
Wim Sinke
ECN Solar Energy, University of Amsterdam
& FOM Institute AMOLF

2. Thank you:
Albert Polman (AMOLF)
Bonna Newman (AMOLF)
Pierpaolo Spinelli (AMOLF)
Tom Gregorkiewicz (UvA)
Katerina Dohnalová (UvA)
Patrick de Jager (ASML)
Michel van de Moosdijk (ASML)
Frank Lenzmann (ECN)
Stefan Luxembourg (ECN)
Arthur Weeber (ECN)
for providing input and inspiration for this presentation!

3. Content
• Photovoltaic solar energy (PV): the challenge quantified
• The building blocks: solar cells in fab and lab
• Where nanotechnology comes in: to and beyond current
performance and cost limits
• Outlook: mature yet young
3

4. Content
• Photovoltaic solar energy (PV): the challenge quantified
• The building blocks: solar cells in fab and lab
• Where nanotechnology comes in: to and beyond current
performance and cost limits
• Outlook: mature yet young
4

5. Solar energy contribution
Solar Energy Perspectives – Testing the Limits (IEA, 2011)
5
(13% of final energy)
= 40.000 km2 module area @ 30% efficiency
= area The Netherlands

6. Solar energy contribution
Shell Lens Scenarios – Oceans (2013)
7

7. Multi-terawatt use
Quantifying the challenge
• Competitive generation costs (from 0.10 €/kWh to 0.05 €/kWh
– 0.5  1 €/Wp system price (dependent on region and market)
• High module efficiencies (from 10  20% to 20  40%+)
– cost reduction lever at all levels
– facilitates large-scale use
• From renewable to fully sustainable (earth-abundant materials?)
– Materials & processes
– Design for sustainability
• Total quality (at very low cost)

8. Content
• Photovoltaic solar energy (PV): the challenge quantified
• The building blocks: solar cells in fab and lab
• Where nanotechnology comes in: to and beyond current
performance and cost limits
• The third dimension: sustainability
• Outlook: mature yet young
10

9. First SolarHyET SolarWürth Solar
Cell & module technologies:
commercial
11
Flat plate: wafer-based silicon (90%)
- monocrystalline
- multicrystalline (& quasi mono)
Module efficiencies 14  22%
ToyotaCity of the Sun (NL)
Concentrator (<1%)
- multi-junction III-V semiconductors
- silicon
Module efficiencies 25  30%
Abengoa/ConcentrixFhG-ISE
Flat plate: thin films (10%)
- silicon
- copper-indium/gallium-diselenide/sulphide (CIGSS)
- cadmium telluride (CdTe)
Module efficiencies 7  13%
ECN’s Black Beauty

10. First SolarHelianthosWürth Solar
Cell & module technologies:
commercial
12
Flat plate: wafer-based silicon (90%)
- monocrystalline
- multicrystalline (& quasi mono)
Module efficiencies 14  22%
ToyotaCity of the Sun (NL)
Trends:
• new cell and module architectures
• high(er) efficiencies – closing lab/fab gap
Trends:
• increasing scale
• differentiation according to application
Concentrator (<1%)
- multi-junction III-V semiconductors
- silicon
Module efficiencies 25  30%
Abengoa/ConcentrixFhG-ISE
Trends:
• commercial applications taking off
• race to 50% lab cell efficiencies
Flat plate: thin films (10%)
- silicon
- copper-indium/gallium-diselenide/sulphide (CIGSS)
- cadmium telluride (CdTe)
Module efficiencies 7  13%

11. Concepts & technologies
Lab and pilot production
• super-high-efficiency concepts
– full use of all light colors (optimize cell or optimize spectrum)
– advanced light management & concentration
• super-low-cost concepts
(& technologies for new applications)
– very fast and non-vacuum processing
– low-cost materials & low material use
13
Example:
spectrum conversion using
quantum dots
(Univ. of Amsterdam)
Example:
polymer solar cell (Solliance)

12. Concepts & technologies
Lab and pilot production
• super-high-efficiency concepts
– full use of all light colors (optimize cell or optimize spectrum)
– advanced light management & concentration
• super-low-cost concepts
(& technologies for new applications)
– very fast and non-vacuum processing
– low-cost materials & low material use
14
Example:
spectrum conversion using
quantum dots
(Univ. of Amsterdam)
Example:
polymer solar cell (Solliance)

13. www.nrel.gov/ncpv/images/efficiency_chart.jpgwww.nrel.gov/ncpv/images/efficiency_chart.jpg

14. www.nrel.gov/ncpv/images/efficiency_chart.jpgwww.nrel.gov/ncpv/images/efficiency_chart.jpg
nanotechnology as driver

15. Ideal single-gap cells
Loss factor Selected remedies
recombination light management incl. concentration
and curve loss 30%  40%
spectral losses multi-gap & multi-band cells
hot carrier cells
multi-carrier generation
spectrum shaping
40%  70%+
`
  30%
Routes to (very) high efficiency
Potential & limits (rounded numbers)

16. Ideal single-gap cells
Loss factor Selected remedies
recombination light management incl. concentration
and curve loss 30%  40%
spectral losses multi-gap & multi-band cells
hot carrier cells
multi-carrier generation
spectrum shaping
40%  70%+
`
  30%
Routes to (very) high efficiency
Potential & limits (rounded numbers)
qVoc < Egap
(JV)max < JmaxVmax
Eph > Eg
Eph < Eg

17. Ideal single-gap cells
Loss factor Selected remedies
recombination light management incl. concentration
and curve loss 30%  40%
spectral losses multi-gap & multi-band cells
hot carrier cells
multi-carrier generation
spectrum shaping
40%  70%+
`
  30%
Routes to (very) high efficiency
Potential & limits (rounded numbers)
qVoc < Egap
(JV)max < JmaxVmax
Eph > Eg
Eph < Eg

18. Ideal single-gap cells
Loss factor Selected remedies
recombination light management incl. concentration
(and curve loss) 30%  40%
spectral losses multi-gap & multi-band cells
hot carrier cells
multi-carrier generation
spectrum shaping
40%  70%+
`
Routes to (very) high efficiency
Potential & limits (rounded numbers)
FhG-ISE
  30%

19. Ideal single-gap cells
Loss factor Selected remedies
recombination light management incl. concentration
(and curve loss) 30%  40%
spectral losses multi-gap & multi-band cells
hot carrier cells
multi-carrier generation
spectrum shaping
40%  70%+
`
Routes to (very) high efficiency
Potential & limits (rounded numbers)
500 1000 1500 2000 2500
0
200
400
600
800
1000
1200
1400
1600
AM15
GaInP
GaInAs
Ge
  30%

20. Ideal single-gap cells
Loss factor Selected remedies
recombination light management incl. concentration
(and curve loss) 30%  40%
spectral losses multi-gap & multi-band cells
hot carrier cells
multi-carrier generation
spectrum shaping
40%  70%+
`
Routes to (very) high efficiency
Potential & limits (rounded numbers)
  30%

21. Ideal single-gap cells
Loss factor Selected remedies
recombination light management incl. concentration
(and curve loss) 30%  40%
spectral losses multi-gap & multi-band cells
hot carrier cells
multi-carrier generation
spectrum shaping
40%  70%+
`
Routes to (very) high efficiency
Potential & limits (rounded numbers)
  30%

22. Ideal single-gap cells
Loss factor Selected remedies
recombination light management incl. concentration
(and curve loss) 30%  40%
spectral losses multi-gap & multi-band cells
hot carrier cells
multi-carrier generation
spectrum shaping
40%  70%+
`
Routes to (very) high efficiency
Potential & limits (rounded numbers)
  30%

23. Content
• Photovoltaic solar energy (PV): the challenge quantified
• The building blocks: solar cells in fab and lab
• Where nanotechnology comes in: to and beyond current
performance and cost limits
• Outlook: mature yet young
25

25. Nanopatterning for high-efficiency PV:
finding the way in a jungle of options
27

26. Challenge: combine the best of two
worlds for a record efficiency
28

27. Example: advanced light management
to cross the 25% efficiency barrier for silicon
29

28. Example: advanced light
management for ultra-thin solar cells (1)
30

29. Example: advanced light
management for ultra-thin solar cells (2)
31

30. Example: enhanced spectrum
utilisation using QDs
32Courtesy: Tom Gregorkiewicz (UvA)

31. Example: spectrum shaping to boost
efficiency (“add-on” to solar cells)
33Courtesy: Tom Gregorkiewicz (UvA)

32. Example: spectrum shaping by Space-
Separated Quantum Cutting using QDs (1)
34Courtesy: Tom Gregorkiewicz (UvA)
Eexc ≥ 2Egap

33. Example: spectrum shaping by Space-
Separated Quantum Cutting using QDs (2)
35Courtesy: Tom Gregorkiewicz (UvA)

34. The Holy Grail?
All-silicon tandem solar cell
36http://iopscience.iop.org/0957-4484/labtalk-article/34339

35. Content
• Photovoltaic solar energy (PV): the challenge quantified
• The building blocks: solar cells in fab and lab
• Where nanotechnology comes in: to and beyond current
performance and cost limits
• Outlook: mature yet young
37

36. Commercial module efficiencies
History & projections (simplified estimates)

37. Commercial module efficiencies
History & projections (simplified estimates)

38. The future at a glance
40
Current 2020
Long-term
potential
Commercial module efficiency flat
plate/concentrator (%)
722 / 2530 1025 / 3035 2050
Turn-key system price (flat plate)
(€/Wp)
13 0.82
(with sustainable
margins)
0.51
Cost of electricity
(LCoE, €/kWh)
0.050.30 0.040.20 0.030.10
Energy pay-back time (yrs) 0.52 0.251 0.250.5
Installed capacity (TWp) 0.1 0.51 10-50

39. The future at a glance
Current 2020
Long-term
potential
Commercial module efficiency flat
plate/concentrator (%)
722 / 2530 1025 / 3035 2050
Turn-key system price (flat plate)
(€/Wp)
13 0.82
(with sustainable
margins)
0.51
Cost of electricity
(LCoE, €/kWh)
0.050.30 0.040.20 0.030.10
Energy pay-back time (yrs) 0.52 0.251 0.250.5
Installed capacity (TWp) 0.1 0.51 10-50
x 23
x ½⅓
x 100+

40. A view on the future
42
City of the Sun,
Municipality of
Heerhugowaard.
Photo:
KuiperCompagnons

41. Thank you for your attention!