The Future of Thin-film Solar Cells

7/29/2019 The Future of Thin-film Solar Cells

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Photovoltaics - Electricity from Sunlight UNSW

“ “ The Future of ThinThe Future of Thin--film Solar film Solar

CellsCells” ”

Martin A. GreenMartin A. GreenUniversity of New South WalesUniversity of New South Wales

Sydney Sydney

UNSW Photovoltaics Centre of Excellence- supported by the Australian Research Council




Photovoltaics booming Photovoltaics booming

2 0 0 0

2 0 0 2

2 0 0 4

2

0 0 6

2 0 0 8

2 0

1 0

0

2

4

6

8

10

N e w C a p a c i t y , G W

Source: Photon International

ThinThin--filmfilm

Bulk Bulk




First generation cells First generation cells

p-type

n ++

p +

metal

150-200 µm2-3 m m

Larger Si wafer area than ICs Larger Si wafer area than ICs

Issues Issues

. thinner cells. thinner cells. simpler Si purification. simpler Si purification

. higher conversion efficiency. higher conversion efficiency




Second Generation: thin Second Generation: thin - - film film

Advantages Advantages

. low materials cost . low materials cost . large manufacturing unit . large manufacturing unit

. fully integrated modules. fully integrated modules

. aesthetics, ruggedness?. aesthetics, ruggedness?

Thin Thin - - film Technologies film Technologies

.. Silicon Silicon . amorphous. amorphous. microcrystalline. microcrystalline. polycrystalline. polycrystalline

.. Chalcogenide Chalcogenide (polycrystalline)(polycrystalline). CIS, CIGS [Cu ( . CIS, CIGS [Cu ( In,GaIn,Ga ) (Se,S) ) (Se,S)2 2 ] ] .. CdTeCdTe

.. Dye sensitised Dye sensitised ,, Organics Organics




Silicon Thin Silicon Thin - - Film Film

aa--Si,Si, µ µ c c --Si, c Si, c --Si Si

amorphous, microcrystalline, (poly amorphous, microcrystalline, (poly -- )crystalline )crystalline




Chalcogenides Chalcogenides : CdTe and CIGS : CdTe and CIGS

. easily deposited . easily deposited

. Cd toxic, Te scarce . Cd toxic, Te scarce

. highest efficiency . highest efficiency

. tricky to deposit . tricky to deposit

. Cd toxic, In scarce . Cd toxic, In scarce CdTeCdTe

CIGSCIGS

glass

TCO

windowalloy layer

absorber

metal contact

SnO2CdS

CdSxTe1-x

CdTe

contact Mo

TCOwindow

absorber

ZnO

glass

Cu (Ga,In) (Se,S)2

CdS

substrate

CuInGaSeSCuInGaSeS




Other Advanced Thin Other Advanced Thin - - Films: Films:

Dye Dye - - sensitised; Organic sensitised; Organic




Cost reduction Cost reduction

20000

10000

5000

2000

1000

500

200 0.01 0.1 1.0 10.0 100.0

Gas turbines (USA)

(~20%, ~10%)

1980

1963

1982

1987 1993

2001

Wind turbines

2002

Cumulative GW installed

1981

Photovoltaics (learning ~20%)

USA (~20%)

World (~5%)

2 0 0 3 U S $ / k

W

Adapted from Adapted from

Gr Gr ü ü bler bler et al.,1999 et al.,1999




ThinThin--filmfilm

Cost reduction Cost reduction

20000

10000

5000

2000

1000

500

200 0.01 0.1 1.0 10.0 100.0

Gas turbines (USA)

(~20%, ~10%)

1980

1963

1982

1987 1993

2001

Wind turbines

2002

Cumulative GW installed

1981

Photovoltaics (learning ~20%)

USA (~20%)

World (~5%)

2 0 0 3 U S $ / k

W“ “ Thin Thin - - film film ” ” Photovoltaics Photovoltaics

Adapted from Adapted from

Gr Gr ü ü bler bler et al.,1999 et al.,1999




The 3 generationsThe 3 generations

II

100

80

60

20

0 100 200 300 400 500

US$0.50/W

US$1.00/W

US$3.50/W

Cost, US$/m2

US$0.10/W US$0.20/W

Present limitIII

Thermodynamiclimit

40

I

E f f i c i e n

c y , %

Bulk Bulk





II

100

80

60

20

0 100 200 300 400 500

US$0.50/W

US$1.00/W

US$3.50/W

Cost, US$/m2

US$0.10/W US$0.20/W

Present limitIII

Thermodynamiclimit

40

I

E f f i c i e n

c y , %

Includes dye, organic Includes dye, organic

ThinThin--filmfilm




Thermodynamic efficiency limitsThermodynamic efficiency limits

Tc

Es

Ss

Ec

Sc

SG>0

TA

W

Q

S = Q/TA

η ≤ (1-T ASs /E s ) = 93.3% (direct) = 73.7% (global)





?

II

100

80

60

20

0 100 200 300 400 500

US$0.50/W

US$1.00/W

US$3.50/W

Cost, US$/m2

US$0.10/W US$0.20/W

Present limitIII

Thermodynamiclimit

40

I

E f f i c i e n

c y , %

. high . high--efficiencyefficiency . thin . thin-- film film . abundant . abundant

. non . non-- toxic toxic . durable . durable




UNSW approachUNSW approach

I I

Evolutionary emphasis Evolutionary emphasis upon crystalline silicon upon crystalline silicon

(robust, abundant, non (robust, abundant, non - -

toxic) toxic)




UNSW approachUNSW approach

I I

II II

Evolutionary emphasis Evolutionary emphasis upon crystalline silicon upon crystalline silicon

(robust, abundant, non (robust, abundant, non - -

toxic) toxic)




Third generation optionsThird generation options

100%

74%

68%

54%49%44%

39%31%

0%

58%

circulators

tandem (n )hot carrier

impurity PV & band, up-converterstandem (n = 3)thermal, thermoPV, thermionics

impact ionisationtandem (n = 2)

down-converterssingle cell

tandem (n = 6)





100%

74%

68%

54%49%44%

39%31%

0%

58%

circulators





tandem (n = 6)




Si Si --based tandemsbased tandems

42.5%

47.5%50.5%

Number of cells

1 2 3

10

20

30

40

0

0

Si bottom cell

Free choice

29%

33%

45%

A M 1 . 5

G

E f

f i c i e n c y

Free choice

or Si cell

Decreasing band gap

Sunlight

Intrinsic radiative and Auger losses included Intrinsic radiative and Auger losses included




Si Si --tandem concept tandem concept

CSG Solar approach CSG Solar approach

. high . high - - T silicon T silicon

. high . high - - density contacts density contacts

. good optics . good optics

. deposit then process . deposit then process

. also suits hot . also suits hot - - carrier carrier

Metal

Resin

p+

n+

Light In

p+p

n+

p

Textured glass

'Crater' 'Groove' 'Dimple'

Up-converters ?

1 - 3 QD cells ?




100nm100nm

Fabrication of Si quantum dotsFabrication of Si quantum dots

SiOx, SiyNx, SiCx

SiO2, Si3N4, SiC

Zacharias et al., APLZacharias et al., APL 80 80 , 661, 2002 , 661, 2002




Si quantum dot photoluminescenceSi quantum dot photoluminescence

Norm. PL Spectra

(2-5nm dots; 300K)

01.2 1.4 1.6 1.8 2

Photon energy, eV

5nm (270s)4nm (240s)

3nm (180s)2nm (120s)

100nm100nm





100%

74%

68%

54%49%44%

39%31%

0%

58%

circulators





tandem (n = 6)




Hot Hot --carrier cell concept carrier cell concept

tunnelingcontact

absorber

100nm100nm

Bandgap (eV)

cold carriers

0.0 0.5 1.0 1.5 2.0 2.5 3.0

80

60

40

20

0

E f f i c i e n c y ( % )

1

2hot carriers

InN Si

quantum dot absorber

hole contactelectron contact

TTaa

TTcc

Efficiency > 4 cell tandem




Summary Summary

.. need to fix carbon problem at sourceneed to fix carbon problem at source – – provide clean, more cost provide clean, more cost --effective electricity optionseffective electricity options

. photovoltaics provides a solution provided . photovoltaics provides a solution provided

– – volumes increased and costs reduced dramatically volumes increased and costs reduced dramatically

. high energy conversion efficiency is the key to lowest . high energy conversion efficiency is the key to lowest

possible long possible long --term coststerm costs. high efficiency thin. high efficiency thin--film technologies described for film technologies described for

post post --2020 era2020 era

The Future of Thin-film Solar Cells

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