insights to high efficiency cigs thin-film solar cells and

Materials Science and Technology

Dr. Stephan Buecheler

Contact: [email protected] Direct: +4158 765 6107

Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology,

Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland;

Insights to high efficiency CIGS thin-film solar cells

and tandem devices with Perovskites

2017 EU-US Frontiers of Engineering Symposium, Davis, US

Materials Science and Technology 2 Laboratory for Thin Films and Photovoltaics / Buecheler / 2017 EU-US FoE

©Fraunhofer ISE: Photovoltaics Report, updated: 12 July 2017

Increasing module efficiency is the key for further reduction of

system prices


Source: http://www.cleanenergyreviews.info/blog/pv-panel-technology

Opportunities with Thin Film PV

Shorter Energy Payback Time

Better Energy Yield

Lower Carbon footprint

Enabling efficiency improvements of Si wafer cells

Innovative production & applications

Better aesthetics


Thin film solar cell

Different layers and configurations

4 Laboratory for Thin Films and Photovoltaics / Buecheler / 2017 EU-US FoE


Thin film solar cell


Band gap engineering by alloying

IV Si

Ge

II - VI Cd

Zn

S

Se

Te III - V

Al

In

Ga

As

P

I – III – VI2

Al, In, Ga

Cu

Ag

Au

S

Se

Te


2015-07-23

Solar Frontier Surpasses 3 GW of Global CIS

Module Shipments

http://www.solar-frontier.com/eng/news/2015/C047775.html

CIGS thin film solar module

Production capacity of >1 GW from 3 manufacturing plants

19.2% conversion efficiency on 30cm x 30cm substrate in March 2017

19.8% conversion efficiency on 7cm x 5 cm substrate in March 2017

23.3% conversion efficiency on a ~0.5cm² CIS cell in November 2017



3.1 MWp of CIS modules near Bonnhof, Germany

(Solar Frontier)

Building integrated CIGS modules in Sweden (Solibro)

Source: http://cigs-pv.net/cigs-thin-film-projects/

Building integrated CIGS with 500 m² (Manz AG)

Lightweight flexible CIGS module (Flisom)

Applications of CIGS: from buildings to utility scale ground mount


http://cigs-pv.net/wortpresse/wp-content/uploads/2015/12/Flisom_Flex_Large_web.jpg

http://cigs-pv.net/wortpresse/wp-content/uploads/2015/12/SolarFrontier-Bonnhof-klein.jpg

http://cigs-pv.net/wortpresse/wp-content/uploads/2015/12/WHB-1_TUD-bearb-klein-2.jpg


Why are we interested in flexible PV modules?


Si wafer or thin film PV on glass:

Heavy & Rigid

Flexible Solar Cells:

• Lightweight Devices

• Potential to reduce grey energy

• Portable and mobile applications

• Building-integrated PV

• Roll-to-roll manufacturing


Pictures for educational purposes; Source: different websites

Thin films (coatings) on flexible substrate are everywhere around us


Flexible and lightweight solar cells / challenges*

Laboratory for Thin Films and Photovoltaics /

Solar cells Mini-modules Solar modules

• How to add

Alkaline/doping

elements

• limited processing

temperature

• Residual stress

management

• Adhesion esp. CIGS

on Mo or CdTe on BC

• How to adjust

compositional grading

(CIGS) or

recrystallization (CdTe)

• …

• All laser based

interconnection of cells

to modules

• Bendable current

collectors

• How to manage

shrinkage or elongation

of substrate

• …

• Transfer of process to R2R inline

equipment

• Development deposition equipment

• In-situ process control on non-flat

substrates

• Flexible encapsulation

• …

Which substrate, which process, …

* List is not complet

Materials Science and Technology 11

CIGS solar cells and mini-modules / state-of-the-art

Laboratory for Thin Films and Photovoltaics / Buecheler / 2017 EU-US FoE

Reinhard, P. et al. IEEE J-PV 3, 572-580 (2013).

Buecheler, S. et al., PV International, January 2015

23.3% SF

22.8% SF

22.6% ZSW


Lightweight Thin Film PV Modules


Image: Flisom

Image: Flisom

Deposition of multilayer stack Monolithical interconnection +

application of bus bars




Image: Flisom

Roll-to-roll manufacturing with annual production capacity of 15 MW installed by Flisom

Installation of lightweight PV modules from Flisom




Image: Flisom

Achievable efficiencies with the CIGS

technology*:

• ~25% on cell level

• 21-22% on module level

* Estimation based on detailed loss analysis

Can we increase the efficiency with no or only slight increase of costs/Wp?

Majority of module costs arise from

substrate,

back side encapsulation,

front sheet;


http://iambaker.net/how-to-build-a-layer-cake/

Towards super high efficiency: >30% thin film solar cells

Stacking of solar cells optimized for different parts of the solar spectrum

Laboratory for Thin Films and Photovoltaics / Buecheler / 2017 EU-US FoE 15


TANDEM lightweight Thin Film PV Modules


Image: Flisom

Milestones

• Flexible and NIR transparent perovskite solar cell

directly on the front sheet material

• Sufficient stability of the perovskite top cell

• Monolithically interconnection by laser scribing

• Scalable deposition methods

• Substitute costly materials (e.g. HTL)

Majority of module costs arise from substrate, back side encapsulation, front sheet;


S. Pisoni et al., J. Mater. Chem. A 5, (2017)

17

Al:ZnO ETL

PbI2

MAI HTL

Flexible Perovskite Solar Cells: Our Device Structure



VOC (V) JSC (mA/cm2) FF (%) ƞ (%) ƞ mpp(%) Cell area (cm2)

Fwd 1.08 18.0 70.2 13.7 13.9 0.27

Bwd 1.07 17.8 71.5 13.6

NIR-transparent Flexible Perovskite Solar Cells


Flexible and NIR transparent solar cell

with ~14% efficiency

18

S. Pisoni et al., in preparation


VOC (V) JSC

(mA/cm2)

FF (%) ƞ (%) ƞmpp(%)

Area

(cm2)

Flexible CIGS 0.67 36.3 77.1 18.9 18.9 0.213

Flexible CIGS bottom cell 0.64 12.8 77.8 6.4 6.4 0.213

Flexible Perovskite top

cell 1.08 18.0 70.2 13.7 13.9 0.27

4-Terminal Flexible Tandem Device

Flexible Perovskite/CIGS tandem solar cell with 20.3% efficiency in 4-Terminal configuration

Laboratory for Thin Films and Photovoltaics / Buecheler / 2017 EU-US FoE 19

S. Pisoni et al., in preparation

C

orr

esponds t

o 2

03 W

/m2 if ill

um

inate

d w

ith 1

sun


Perovskite-based Tandem Solar Cells

Updated September 2017



Solar cell efficiencies have crossed 22% bench mark and further

efforts are being made towards 25%

High efficiency flexible and lightweight solar cells are expected to

open new application opportunities

Several untapped market opportunities – especially attractive for

buildings, transportation, portable, large-lightweight ground mounts

New materials, new deposition processes and multi-junctions

concepts show potentials for >30% thin film solar cells, but several

challenges have to be overcome

Summary and Outlook


sub-cell efficiency – band gap of top and bottom cell – transmission through top cell – recombination layer – NIR

response in bottom cell – stability of top cell – scaling the deposition processes – substitute costly materials …


Acknowledgements EU-commission FP7 project «hipoCIGS» (project number: 241384)

EU-commission FP7 project «R2R-CIGS» (project number: 283974)

EU-commission Horizon 2020 project «Sharc25» (project number:641004)

Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number REF-1131-52107

The Competence Center for Energy and Mobility in ETH Domain (DURSOL, CONNECT-PV)

The Swiss National Science Foundation / The Swiss Federal Office of Energy /

NanoTera / Comission for Tech. and Innovation

The Laboratory for Nanoscale Materials Science at Empa (SIMS, XPS)

The Laboratory for Electronics/Metrology/Reliability at Empa (SEM)

The Laboratory for Analytical Chemistry at Empa (ICP-MS)

Flisom AG

All current and former members of the Lab for Thin Films and Photovoltaics at Empa

Collaboations with ZSW, HZB, Luxembourg, Uni Rouen, Uni Parma, Alto Univ, Manz, Flisom, (Sharc25 proect)

Disclaimer:

The opinions expressed and arguments employed herein do not necessarily reflect the official views of the

Swiss Government or the European Agency

Thank you for your attention

E-MRS Spring Meeting 2018, June 18th-22nd, Strasbourg

Symposium A: Thin Film Chalcogenide Photovoltiac Materials;

includes workshop on kesterite solar cells organizers: Stephan Buecheler, Daniel Abou-Ras, Negar Naghavi, Woo Kyoung Kim, Alexander Uhl

insights to high efficiency cigs thin-film solar cells and

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