“The Future of Thin-film Solar Cells” - TV Worldwide Green.pdf · UNSW Photovoltaics -...

Photovoltaics - Electricity from Sunlight UNSW

““The Future of ThinThe Future of Thin--film Solarfilm SolarCellsCells””

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

SydneySydney

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


Photovoltaics boomingPhotovoltaics booming20

00

2002

2004

2006

2008

2010

0

2

4

6

8

10

New

Cap

acity

, GW

Source: Photon International

ThinThin--filmfilm

BulkBulk


First generation cellsFirst generation cells

p-type

n ++

p +

metal

150-200 µm2-3 m m

Larger Si wafer area than ICsLarger Si wafer area than ICs

IssuesIssues

. thinner cells. thinner cells

. simpler Si purification. simpler Si purification

. higher conversion efficiency. higher conversion efficiency


Second Generation: thinSecond Generation: thin--filmfilm

AdvantagesAdvantages. low materials cost. low materials cost. large manufacturing unit. large manufacturing unit. fully integrated modules. fully integrated modules. aesthetics, ruggedness?. aesthetics, ruggedness?

ThinThin--film Technologiesfilm Technologies. . SiliconSilicon

. amorphous. amorphous

. microcrystalline. microcrystalline

. polycrystalline. polycrystalline. . ChalcogenideChalcogenide (polycrystalline)(polycrystalline)

. CIS, CIGS [Cu (. CIS, CIGS [Cu (In,GaIn,Ga) (Se,S)) (Se,S)22]]

. . CdTeCdTe. . Dye sensitisedDye sensitised, , OrganicsOrganics


Silicon ThinSilicon Thin--FilmFilm

aa--Si, Si, µµcc--Si, cSi, c--SiSiamorphous, microcrystalline, (polyamorphous, microcrystalline, (poly--)crystalline)crystalline


ChalcogenidesChalcogenides: 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 scarceCdTeCdTe

CIGSCIGS

glassTCO

windowalloy layer

absorbermetal contact

SnO2CdS

CdSxTe1-x

CdTe

contact Mo

TCOwindow

absorber

ZnO

glass

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

CdS

substrate

CuInGaSeSCuInGaSeS


Other Advanced ThinOther Advanced Thin--Films:Films:DyeDye--sensitised; Organicsensitised; Organic


Cost reductionCost reduction

20000

10000

5000

2000

1000

500

2000.01 0.1 1.0 10.0 100.0

Gas turbines (USA)(~20%, ~10%)

1980

1963

1982

19871993

2001

Wind turbines 2002

Cumulative GW installed

1981

Photovoltaics(learning ~20%)

USA (~20%)

World (~5%)

2003

US$

/kW

Adapted from Adapted from GrGrüüblerbler et al.,1999et al.,1999


ThinThin--filmfilm

Cost reductionCost reduction

20000

10000

5000

2000

1000

500

2000.01 0.1 1.0 10.0 100.0

Gas turbines (USA)(~20%, ~10%)

1980

1963

1982

19871993

2001

Wind turbines 2002

Cumulative GW installed

1981

Photovoltaics(learning ~20%)

USA (~20%)

World (~5%)

2003

US$

/kW

““ThinThin--filmfilm”” PhotovoltaicsPhotovoltaics

Adapted from Adapted from GrGrüüblerbler et al.,1999et 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

Effic

ienc

y,%

BulkBulk



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

Effic

ienc

y,%

Includes dye, organicIncludes dye, organic

ThinThin--filmfilm


Thermodynamic efficiency limitsThermodynamic efficiency limits

Tc

EsSs

Ec

Sc

SG>0

TA

W

Q

S = Q/TA

η ≤ (1-TASs/Es) = 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

Effic

ienc

y,%

. high. high--efficiencyefficiency

. thin. thin--filmfilm

. abundant. abundant

. non. non--toxictoxic

. durable. durable


UNSW approachUNSW approach

II

Evolutionary emphasis Evolutionary emphasis upon crystalline siliconupon crystalline silicon

(robust, abundant, non(robust, abundant, non--toxic)toxic)



II

IIII

Evolutionary emphasis Evolutionary emphasis upon crystalline siliconupon crystalline silicon




?II

IIII

IIIIIIEvolutionary emphasis Evolutionary emphasis upon crystalline siliconupon crystalline silicon



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)


SiSi--based tandemsbased tandems

42.5%47.5%

50.5%

Number of cells1 2 3

10

20

30

40

00

Si bottom cellFree choice

29%

33%

45%

AM1.

5G E

ffici

ency

Free choiceor Si cell

Decreasing band gap

Sunlight

Intrinsic radiative and Auger losses includedIntrinsic radiative and Auger losses included


SiSi--tandem concepttandem concept

CSG Solar approachCSG Solar approach. high. high--T siliconT silicon

. high. high--density contactsdensity contacts

. good optics. good optics

. deposit then process. deposit then process

. also suits hot. also suits hot--carriercarrier

MetalResinp+

n+

Light In

p+pn+

p

Textured glass'Crater' 'Groove' 'Dimple'

Up-converters ?

1 - 3 QD cells ?

Photovoltaics - Electricity from Sunlight UNSW100nm100nm

Fabrication of Si quantum dotsFabrication of Si quantum dots

SiOx, SiyNx, SiCxSiO2, Si3N4, SiC

Zacharias et al., APL Zacharias et al., APL 8080, 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


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)


HotHot--carrier cell conceptcarrier 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

Effic

ienc

y (%

) 1

2hot carriers

InN Si

quantum dot absorber

hole contactelectron contact

TTaa

TTcc

Efficiency > 4 cell tandem


SummarySummary

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

. photovoltaics provides a solution provided. photovoltaics provides a solution provided–– volumes increased and costs reduced dramaticallyvolumes increased and costs reduced dramatically

. high energy conversion efficiency is the key to lowest . high energy conversion efficiency is the key to lowest possible longpossible long--term coststerm costs

. high efficiency thin. high efficiency thin--film technologies described forfilm technologies described forpostpost--2020 era2020 era

“The Future of Thin-film Solar Cells” - TV Worldwide Green.pdf · UNSW Photovoltaics -...

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