We presepresentedabout 100stoichiomorthorhomunder cerdiffractionloosely pasemicondfilms also for solar cspectrum sufficient absorber

ent a new procd at the confe0 to 250 oC. Netric to within

mbic structurertain conditionn. The morphoacked plates, ucting with ligshow strong

cells with maxand over 104

to absorb momaterial in th

equiax

AL

Prasert Sinse

Ha

*Em

cess for ALD rence. The pr

No impurities wn the measurine normally founs a minor amology of the fidepending o

ghtly p-type dphotoconduc

ximum efficien4 cm-1 in the nost of the solain-film solar c

xed columnar

1.E+00

1.E+02

1.E+04

1.E+06

(cm

1 )

LD of Tin

ermsuksakul,

rvard Univers

mail: Gordon@

of tin(II) sulfidrocess operatwere detectedng accuracy ond in the bulk

mount of a cublms varies fron the substraoping (1015 to

ctivity. Their oncy. The opticnear infrared).ar spectrum. Tcells made of

grains

0

2

4

6

1.00 1.25 1.50

Absorption c

Monosulf

Adam S. Hock

sity, Cambrid

@chemistry.h

de, SnS, fromtes at low subd in the deposof RBS, abouk material (asbic phase is aom dense equte and growtho 1016 holes coptical band gcal absorption. Thus a very These propertearth-abunda

0 1.75 2.00 2.2hv (eV)

coefficient for 3

fide, SnS

k and Roy G.

ge, MA USA

harvard.edu

m H2S and a nbstrate tempesited materiat + 1%. The p

s in the mineraalso detected uiaxed columnh conditions. Tcm-3 and holegap is about 1n is very stronsmall thickne

ties make SnSant and non-t

p

25 2.50 2.75 3.

film thicknesse

---- 110nm---- 230nm---- 380nm

Gordon*

novel tin sourceratures, in thl by XPS or Rphase correspal Herzenbergby X-ray andnar polycrystaThe SnS film mobility > 6 c.3 eV, which

ng (over 105 cess, less thanS a good canoxic materials

platelets

00

es

ce that will bee range from

RBS. The filmsponds to the gite) , althoug electron alline films to s are cm2 V-1 s-1). Tis nearly opti

cm-1 in the visn 0.5 micron, indidate for thes.

e

s are

gh

Themum

sibleise

ALD

ofTi

nM

onos

ulfid

eSn

SA

LD o

f Tin

Mon

osul

fide,

SnS

Pras

ert S

inse

rmsu

ksak

ul, A

dam

S. H

ock

and

Roy

G. G

ordo

nHa

rvar

d Un

iver

sity

Cam

brid

geM

AUS

AC

ambr

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, MA

USA

Har

vard

Uni

vers

ity

Out

line

Thin

-film

sol

ar c

ells

the

need

for s

olar

pow

erp

eart

h-ab

unda

nt, n

on-to

xic

abso

rber

: SnS

ALD

proc

ess

forS

nSA

LD p

roce

ss fo

r SnS

new

tin

prec

urso

rgr

owth

per

cyc

le

SnS

film

pro

pert

ies

com

posi

tion

pst

ruct

ure

optic

al p

rope

rtie

sel

ectr

ical

prop

ertie

s

Har

vard

Uni

vers

ity

elec

tric

al p

rope

rtie

s

2

Glo

bal E

nerg

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se b

y H

uman

s

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nerg

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tera

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ts (1

4 x

1012

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ts)

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ce:I

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natio

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nerg

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(IEA)

Har

vard

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Cur

rent

ene

rgy

supp

ly is

uns

usta

inab

le-e

nviro

nmen

tally

, eco

nom

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ly &

soc

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tern

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Sola

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The

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a re

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(110

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2 )3

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(0.2

kW

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~3x

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TW

15%

ffii

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tal l

and

area

=>

14 T

W

Har

vard

Uni

vers

ity4

Flat

-Pan

el P

hoto

volta

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anta

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high

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actu

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posi

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low

effic

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ells

-

pote

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low

est c

ost

long

term

inst

abili

ty

Har

vard

Uni

vers

ity

CdT

eP

V m

odul

es(F

irst S

olar

Inc.

)C

IGS

PV

mod

ule

(Glo

bal S

olar

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Si P

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)

5

SnS:

Alte

rnat

e A

bsor

ber L

ayer

in S

olar

PV

Cf

Bas

ic C

riter

ia fo

r the

Abs

orbe

r Mat

eria

l.

Suita

ble

band

gap

( Eg

~ 1.

0-1.

5 eV

)

Hig

hqu

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fort

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dca

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igh

quan

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ld fo

r the

exc

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carr

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Long

diff

usio

n le

ngth

/ lo

w c

ombi

natio

n ve

loci

ty

PVef

ficie

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PV e

ffici

ency

Hig

h op

tical

abs

orpt

ion

coef

ficie

nt (1

04-1

05 c

m-1

)

smal

l mas

s of

mat

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l re q

uire

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Con

stitu

ent e

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ents

are

non

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c an

d ab

unda

nt

non-

haza

rdou

s, s

cala

ble,

low

cos

t PV

SnS

has

thes

e pr

oper

ties

Har

vard

Uni

vers

ity6

Tin(

II) A

mid

inat

eas

ALD

Pre

curs

or

Ni Pr

Ni Pr

Sn

NN

i Pr

i Pr

bis(

N,N

’-diis

opro

pyla

ceta

mid

inat

o)tin

(II)

Sn-N

bon

ds =

> re

activ

e to

H2S

Che

late

stru

ctur

e=>

ther

mal

stab

ility

Che

late

stru

ctur

e =>

ther

mal

sta

bilit

yH

ydro

carb

on li

gand

s=>

vol

atili

ty

Har

vard

Uni

vers

ity7

ALD

Pro

cess

for S

nS

6.00

E+1

7

7.00

E+1

7

ty Sn

area

l den

sity

vs

# of

cyc

les

3.00

E+1

7

4.00

E+1

7

5.00

E+1

7

real densioms/cm2)

0.00

E+0

0

1.00

E+1

7

2.00

E+1

7

Snar(ato

010

0020

0030

0040

0050

0060

00

# of

cyc

les

Har

vard

Uni

vers

ity8

Tem

pera

ture

Dep

ende

nce

of G

row

th

250

E+1

6

3.00

E+1

6

SnA

real

Den

sity

vs.

Sub

stra

te T

1.50

E+1

6

2.00

E+1

6

2.50

E+1

6oms/cm2) 0.

00E

+00

5.00

E+1

5

1.00

E+1

6

Sn(ato

100

150

200

250

300

Subs

trat

e te

mpe

ratu

re (o

C)

Har

vard

Uni

vers

ity9

SnS

Com

posi

tion

701.

21.

41.

61.

8En

ergy

(MeV

)

5060 Yield

SnS

203040 NormalizedY

SnS 1

+0.0

1

800

900

1000

1100

1200

1300

1400

Ch

l

010S

Cl

Sn

Cha

nnel

Har

vard

Uni

vers

ity10

SEM

of S

nSFi

lms

Dep

osite

d at

120

o C20

0 cy

cles

1000

cyc

les

3000

cyc

les

5000

cyc

les

5000

cyc

les

Har

vard

Uni

vers

ity

y

11

Dis

tort

ed N

aClS

truc

ture

of S

nSFi

lms

TEM

(+el

ectro

n di

ffrac

tion)

liter

atur

eXR

DTE

MM

iller

idi

()

liter

atur

eXR

DTE

Min

dice

sd S

nS(Å

)d X

RD

(Å)

d TE

M(Å

)hk

l22

.01

4.03

54.

001

3.87

110

26.01

3.42

33.

404

3.33

120

2747

324

43

243

021

27.47

3.24

43.

243

021

30.47

2.93

12.

919

101

31.53

2.83

52.

823

2.84

111

2.59

7-

2.53

121

39.05

2.30

52.

302

2.29

131

44.73

2.02

42.

021

2.02

141

45.49

1.99

211.

999

002

51.31

1.77

91-

1.78

151

53.15

1.72

191.

722

122

5667

162

281

626

162

042

X-R

ay D

iffra

ctio

n (X

RD

) 56.67

1.62

281.

626

1.62

042

Ort

horh

ombi

c St

ruct

ure:

a b

c a

nd

= =

= 90

o

og(CPS)

Har

vard

Uni

vers

ity

1520

2530

3540

4550

5560

l

2 (d

egre

e)

Top

view

alo

ng b

axi

sS

ide

view

12

SnS

has

Very

Str

ong

Opt

ical

Abs

orpt

ion

1.E

+05

1.E

+06

(cm1)

(1)8

0nm

film

s of

var

ious

thic

knes

ses

> 10

4cm

-1fo

r > 1

.4 e

V

1E

01

1.E

+02

1.E

+03

1.E

+04

ptioncoef.

(1) 8

0 nm

(2) 1

50 n

m(3

) 210

nm

(4)3

80nm

(1)

(2)

(3)

(4)

> 10

5cm

-1fo

r > 2

.0 e

V

1.E

+00

1.E

+01 1.

001.

251.

501.

752.

002.

252.

502.

753.

00

Absorp

Phot

on e

nerg

y h

(eV)

(4) 3

80 n

mSo

lar c

ell <

1

m th

ick

little

mat

eria

l nee

ded

Ban

d ga

p fo

r thi

cker

film

s ~

1.3

eV, o

ptim

um fo

r sol

ar c

ells

Bd

dith

ii

filth

ik

Ban

d ga

p de

crea

ses

with

incr

easi

ng fi

lm th

ickn

ess

=> la

r ge

exci

ton

diam

eter

, sm

all e

ffect

ive

mas

s, h

igh

mob

ility

Har

vard

Uni

vers

ity13

gg

y

Elec

tric

al P

rope

rtie

s

Har

vard

Uni

vers

ity14

SnS

isan

abso

rber

fore

arth

abun

dant

non

toxi

cso

larc

ells

Sum

mar

ySn

Sis

an

abso

rber

for e

arth

-abu

ndan

t, no

n-to

xic

sola

r cel

ls

ALD

from

tin(

II) a

mid

inat

ean

d H

2S =

> Sn

S

pure

, sto

ichi

omet

ric, p

olyc

ryst

allin

e Sn

S

optic

al a

nd e

lect

rical

pro

pert

ies

suita

ble

for t

hin

sola

r cel

ls

ALD

sui

tabl

e fo

r pro

toty

pe d

epos

ition

of s

olar

cel

ls(w

ell-c

ontr

olle

d co

mpo

sitio

n an

d st

ruct

ure)

anot

her p

ossi

ble

appl

icat

ion:

thin

-film

tran

sist

ors

on p

last

ic

Har

vard

Uni

vers

ity15

Ack

now

ledg

emen

tsH

all m

easu

rem

ents

don

e w

ith M

ark

Win

kler

and

Eric

Maz

ur

Supp

ortf

rom

the

Dre

yfus

Foun

datio

nSu

ppor

t fro

m th

e D

reyf

us F

ound

atio

n

Har

vard

Uni

vers

ity16