1
Adv
ance
sAdv
ance
sin
in
Th
inTh
inFi
lm
Film
Sili
con
Silic
onPh
otov
olta
ics
Phot
ovol
taic
s
Lucia Vittoria Mercaldo
ENEA
-Po
rtic
i Res
earc
hCe
nter
Phot
ovol
taic
Tech
nolo
gies
Sec
tion
NIS
Col
loqu
im, T
orin
o Ju
ne23
, 200
8
2
Concentration
Concentrationphotovoltaics
photovoltaics
Silicon
Siliconthin
thinfilm PV
film PV technology
technology
III generation
III generation
approaches
approaches
and
and organic
organicdevices
devices
ENEA
ENEA R&D
R&Dmedium
medium-- long
long term
term
activities
activities
ENEA
Portici
Research
Center
3
Thin
Thinfilm Si
film Si research
researchgroup
group&
& projects
projects
Researchers
:
Ma
ria
Lu
isa
Ad
do
niz
io
Ma
rco
De
lla N
oce
Pa
ola
De
lliV
en
eri
Lu
cia
V.
Me
rca
ldo
OngoingProjects:
•F
oto
en
erg
ia(M
IUR
)[P
art
ne
rs:E
NE
A (
co
ord
ina
tor)
, C
ES
I R
ice
rch
e,
Un
ive
rsity o
f P
arm
a, F
err
ara
, B
olo
gn
a a
nd
Na
po
li “F
ed
eri
co
II”
]
•A
gre
em
en
t E
NE
A -
Fo
nd
azio
ne
Tro
nc
he
tti-
Pro
ve
ra
Proposals:
Su
n_
to_
Gri
dP
roje
ct
(“In
du
str
ia 2
01
5”,
with
ST
Mic
roe
lectr
on
ics
as
pro
po
ne
nt)
Head of PV Technologies Section
Ca
rlo
Pri
va
to
Research fellows:
Iuri
eU
sa
tii
Cla
ud
ia D
iletto
Ph.D. Students:
Em
ilia
Esp
osito
Lu
igi F
usco
4
Outline
Outline
PV
mar
ket
over
view
Adv
anta
ges
of t
hin
film
Si P
V
St
ate
of t
he a
rt o
n th
infil
m S
i sol
arce
lls
R&
Dac
tivity
in E
NEA
(Po
rtic
i Res
earc
hCen
ter)
-TC
O d
evel
opm
ent
-M
icro
mor
phde
vice
s-
Sola
rce
llson
pol
imer
icsu
bstr
ate
-II
I ge
nera
tion
appr
oach
es ENEA
Port
ici
Res
earc
hCe
nter
Kane
kain
stal
latio
ns
5
CdTe
CdTe
22,, 77%%
aa-- Sithin film
Sithin film
33,, 99%%
Rib
bon
(Si)
Rib
bon
(Si)
2,2,77
%%
aa-- SiSi
cc--SiSi
6,0%
6,0%
38,0%
38,0%
46,
46, 66%%
CISCIS
00,, 22%%
CdTe
CdTe
22,, 77%%
aa-- Sithin film
Sithin film
33,, 99%%
Rib
bon
(Si)
Rib
bon
(Si)
2,2,77
%%
aa-- SiSi
cc--SiSi
6,0%
6,0%
38,0%
38,0%
46,
46, 66%%
CISCIS
00,, 22%%
monocrystallineSi
multicrystallineSi
on
Ref:
PV
Ne
ws,
Ap
ril2
00
7
Photovoltaic
Photovoltaicproduction
production bybytechnology
technology
Now
aday
s PV
pro
duct
ion
is d
omin
ated
by
crystalline silicon
modules
(in
diff
eren
t fo
rms)
, w
hich
rep
rese
nt
abov
e 90% of the
market.
Up
to
no
wth
e m
ain
ad
va
nta
ge
of
this
tech
no
log
yw
as
tha
tco
mp
lete
pro
du
ctio
n
line
sco
uld
be
bo
ug
ht,
in
sta
lled
an
d b
eu
p a
nd
pro
du
cin
gw
ith
ina
re
lative
lysh
ort
tim
e-f
ram
e(l
ow
-ris
kp
lace
me
nt
with
hig
h e
xp
ecta
tio
ns
for
retu
rn o
n in
ve
stm
en
ts).
How
ever
, th
e on
goin
g sh
orta
ge o
f Si
waf
er f
eed
stoc
k w
ill b
e a
bott
lene
ck f
or s
usta
inin
g th
e pr
esen
t gr
owth
rat
e fo
r c-
Siba
sed
PV!
6
Shou
ldth
e an
noun
ced
incr
ease
sbe
real
ised
, to
tal p
rodu
ctio
n ca
paci
ties
will
then
stan
d at
23
GW
by
the
end
of t
his
deca
de, of
whi
ch6
GW
cou
ldbe
thin
film
s.
BOOM or BUBBLE?
A chance
A chance for
forthin
thinfilm PV
film PV
Euro
pean
Com
mis
sion
Join
tRes
earc
hCen
tre
Inst
itute
for
Envi
ronm
ent
and
Sust
aina
bilit
y
PV Status Report2007
ArnulfJäger-Waldau
Sour
ce:
An
no
un
ce
dC
ap
ac
ity
Inc
rea
se
7
Eq
ua
llyco
mp
etitive
te
ch
no
log
ies
are
am
orp
ho
us/m
icro
mo
rph
Sili
co
n,
Cd
Te
an
d C
u(I
n,G
a)(
S,S
e)2
th
infilm
s.
In a
dd
itio
nD
ye
-ce
llsa
re g
ettin
g
rea
dy
toe
nte
rth
e m
ark
et.
The
reas
onis
prob
ably
that
12 to13 companiesoffer
“turn-key”systems.
Thin Film Industries:
more than 130 companies
in the world
Announced Production Capacities by Technology
Announced Production Capacities by Technology
Rec
ent
new
s in
Ita
ly:
agre
emen
t be
twee
n ENEL
and Sharp
on joi
nt s
tudi
es
on t
ripl
e ju
nctio
n th
in f
ilm P
VSo
urce
: W
alda
u, P
V S
tatu
s Rep
ort
2007
68
co
mp
an
ies
are
sil
ico
nb
as
ed
8
1-3
Advantages of thin film
Advantages of thin film SiSitechnology
technology
Reduction of production costs.
Reduction of the active material.
a-S
ith
in f
ilms a
bso
rb s
un
ligh
t b
ett
er
tha
n
c-S
i, a
nd
ca
n b
e m
ad
e a
t lo
w t
em
pe
ratu
re
on
lo
w-c
ost
su
bstr
ate
s (
gla
ss,
me
tal fo
ils,
an
d p
lastics).
Silic
on b
and
gap
(1.1
eV)
is a
lmos
t op
timum
to
mak
e a
sing
le jun
ctio
n so
lar
conv
erte
r. I
n ad
ditio
n Si
is t
he m
ost
abun
dant
min
eral
on
Eart
h an
d its
dis
posa
l doe
s no
t cr
eate
any
po
llutio
n pr
oble
m.
9
Goo
d ou
tdoo
r pe
rfor
man
ce in
ter
ms
of
gene
rate
d po
wer
, es
peci
ally
at
high
er
ambi
ent
tem
pera
ture
, ev
en w
hen
com
pare
d to
the
bes
t c-
Sim
odul
es.
Outdoor performance and
Outdoor performance and energy
energypayback
paybacktime
time
Sourc
e:
htt
p:/
/ww
w.p
v.k
ane
ka.c
o.jp/w
hy/
EPT
isth
e tim
e to
"pay
back
" th
e en
ergy
used
in t
he P
V m
od
ule
man
ufac
ture
byits
own
pow
er g
ener
atio
n.
10
Deposition Processes on large area for high
Deposition Processes on large area for high
production volumes
production volumes
11
12
13
Products can be made lightweight and flexible
Products can be made lightweight and flexible
14
See
See-- through products are available
through products are available
15
Potentiality to allow a large diffusion of PV in architecture
Potentiality to allow a large diffusion of PV in architecture
16
1976
: Car
son
and
Wro
skire
port
on t
he
first
a-S
i:H
sol
arce
ll.
Th
ere
are
tw
o m
ajo
r is
su
es:
•lo
we
r e
ffic
ien
cy w
ith
re
sp
ect
to c
-Si,
•sta
bili
ty p
rob
lem
s(l
igh
t in
du
ce
d e
ffic
ien
cy
red
uctio
n d
ue
to
me
tasta
ble
de
fect
cre
atio
n
in th
e m
ate
ria
l. S
atu
ratio
n a
fte
r ~
10
00
h)
a-S
i:H
1980
: Sc
hott
Sola
rst
arts
a-Si
:H s
olar
cell
prod
uctio
n on
gla
ss,
follo
wed
bySa
nyo
in 1
982.
Brief
Briefhistory
history(1)
(1)
17
Brief
Briefhistory
history(2)
(2)
1994
: Fi
rst
µc-
Si:H
and
mic
rom
orph
tand
em s
olar
cell
real
ized
at I
MT
-U
nive
rsity
of
Neu
chat
el(S
witz
erla
nd).
1996
: U
nite
dSo
lar
star
tsa-
Si:H
so
lar
cell
prod
uctio
n on
fle
xibl
esu
bstr
ates
.
1999
: Ka
neka
dem
onst
rate
sfir
st m
icro
mor
phm
odul
e.
Be
tter
sta
bilit
y to
ligh
t so
akin
gBe
tter
sta
bilit
y to
ligh
t so
akin
g
Lo
ng w
avel
engt
h re
spon
seLo
ng w
avel
engt
h re
spon
seconglomerate
of nanograins
amorphous
region
substrate
µc-
si:H
has
som
e in
tere
stin
g pe
culia
ritie
s:
Ver
satil
e co
mpl
ex m
ater
ial
cont
aini
ng
mic
rom
eter
si
zed
cong
lom
erat
es
of
nano
grai
ns(∼
20-3
0nm
) in
am
orph
ous
tissu
e.
18
Thin film silicon solar cells
Thin film silicon solar cells
Metal contact
electons
holes
E
Solar
radiation
substrate
TCO
pn
i
Su
n lig
ht e
nter
s th
roug
h th
e p
laye
r w
hich
is
calle
d w
indo
w la
yer
Th
e in
trin
sic
laye
r is
the
act
ive
mat
eria
l
Th
e ph
otoc
arrier
sar
e sw
ept
away
by
th
e bu
ilt-in
elec
tric
fie
ld t
o th
e n-
type
and
p-t
ype
laye
rs.
p-i-n
or n
-i-p
junc
tions
19
Amorphous
Amorphoussilicon
siliconmultijunction
multijunctionsolar
solarcells
cells
np
i
a-Si:H
TCO
blue
Sun
Sunlight
light
Ag
Stainless
Steel
pi
n
a-SiG
e:H
red
pi
a-SiG
e:H
n
green
UnitedSolar
The
“spe
ctru
m
split
ting”
dete
rmin
es
high
er
effic
ienc
y w
ith
resp
ect
to t
he s
ingl
e ju
nctio
n.
Due
to
thin
ner
activ
e la
yer
in e
ach
junc
tion
the
light
soa
king
ef
fect
is r
educ
ed.
Series
of c
ells
usin
gm
ater
ials
with
diff
eren
ten
ergy
gap
devo
ted
toab
sorb
diff
eren
tpa
rts
of t
he s
olar
spec
trum
20
Record on
Record on initial
initialefficiency
efficiency
a-Si
:H/a
-SiG
e:H
/nc-
Si:H
tripl
e-ju
nctio
nso
lar
cells
activ
e-ar
ea:
0.25
cm
2
IEE
E 2
00
8
21
Neuchâtel
11.0
Stab.
0.692
13.5
1.284
0.25
a-Si/
µc-Si
IPV Jülich
9.8
Notstab.
0.70
25.7
0.545
1µc-Si
United
solar
13.0
Stab.
0.697
8.11
2.30
0.25
a-Si/a-
SiGe/a.SiGe
United
Solar
9.3
Stab.
0.672
14.36
0.965
0.25
a-Si
Laboratory
Efficiency
(%)
FF
(%)
Jsc
(mA/cm2)
Voc
(V)
Area
(cm2)
Cell
structure
State of the art at lab scale
State of the art at lab scale
22
ENEA activities on thin film silicon solar cells
ENEA activities on thin film silicon solar cells
Development of transparent and conductive oxide
Development of transparent and conductive oxide
(TCO) films
(TCO) films
Tandem
Tandem ““micromorph
micromorph””solar cells
solar cells
Solar cells on
Solar cells on polimeric
polimericsubstrates
substrates
Third generation approaches
Third generation approaches
23
Light trapping issues
Light trapping issues
The use of a rough transparent
conductive oxide (TCO) layer is
essential in order to increase the
efficiency of thin film solar cells.
Requirements for high-quality TCO:
H
igh
elec
tric
al c
ondu
ctiv
ity
H
igh
tran
spar
ency
H
igh
light
-sca
tter
ing
abili
ty (
haze
rat
io
H=
T diff
use/
Tto
tal)
24
Transparent and conductive oxide
Transparent and conductive oxide(TCO)
(TCO)
Development of acustomizedLP-MOCVD system to deposit
ZnOtextured films on large areasubstrates(30x30cm2)
Deposition
Depositionsystem
system
The texturing producesa
good light-trapping effect
0
0.2
0.4
0.6
0.81 40
045
0500
550
600
650
700
750
800
Quantum Efficiency
Wavelength (nm)
Jsc=
16
.1 m
A/c
m2
Jsc=
17
.0 m
A/c
m2
Sn
O2
Zn
O
AF
M im
ag
eo
f th
e
textu
red
su
rfa
ce
25
Te
xtur
ed m
ater
ial o
n 30
x 3
0 cm
2ar
ea.
G
row
th r
ate
> 2
8 Å/s
ec.
G
ood
thic
knes
s un
iform
ity (
±5%
).
G
ood
elec
tric
al p
rope
rtie
s (R
esis
tivity
= 1
x 1
0-3
Ωcm
, M
obili
ty =
32
cm2 /
Vs)
.
H
igh
tran
spar
ency
(> 8
2 %
).
Enea
Enea results
results: LP
: LP-- MOCVD
MOCVDZnO
ZnO
Next
Nextstep
step: : industrial
industrialscale
scale-- up
up
26
Micromorphtandem solar cells ZnO/Ag
glas
s
TCO
blue
Sun
Sunlight
light
red
np
i
a-Si:H
pi
n
µc-Si:H
Better
utilization of
the solar
spectrum: the spectral sensitivity of
the device is enlarged towards the
near-infrared region
The light-induced degradation typical
of a-Siis effectively reduced
Amorphous top cell + microcrystalline bottom cell
Advantages
Advantages::
1.7
5e
V1
.1e
V
E
limin
atio
n o
f co
stly g
erm
an
ium
ga
s
fro
m th
e m
ultiju
nctio
nfa
bri
ca
tio
n p
roce
ss
27
Maximum
Maximum efficiency
efficiencyplot for tandem
plot for tandem cells
cells
Stillveryfar fromupperlimit
Researchisneeded!
Upp
eref
ficie
ncy
limit
for
micro-morphtandem
cell:
η> 30 %
F. M
eilla
udet
al.,
Sol
. En
ergy
Mat
er.
Sol.
Cel
ls90
, 29
52 (
2006
).Cou
rtes
yof
Prof
. A. Sh
ah,
Uni
v. N
euch
atel
(Sw
itzer
land
)
Gap
s of
µc-S
i:H
(1.1
eV)
and
a-Si
:H(1
.75
eV)
form
an a
lmos
tid
eal
com
bina
tion.
28
Ver
yH
igh
Freq
uenc
yPE
CVD
(V
HF
PECVD
)
H
ot W
ireCVD
(H
W C
VD
)
Trends in current thin film technology
Trends in current thin film technology
De
velo
pm
en
t o
f fa
ste
r
dep
osit
ion
tech
niq
ues:
Fairly
“thi
ck”
(> 1
µm)
mic
rocr
ysta
lline
(slo
wly
depo
site
d) a
bsor
ber
laye
rsar
e ne
eded
!
29
Technique
Technique: VHF PECVD at 100
: VHF PECVD at 100 MHz
MHz
gas
gas mixture
mixtureSiHSiH
44and H
and H
22
Microcrystalline
MicrocrystallineSi (
Si (
µ µµµµ µµµcc
-- Si
Si :
H:H) in ENEA
) in ENEA
4.0
4.5
5.0
5.5
6.0
6.5
7.0
13579
267 Pa
200 Pa
67 Pa
40 Pa
Growth rate (Å/s)
SC (%)
Hig
h pr
essu
re r
egim
e
Low
pre
ssur
e re
gim
e
Deposition
Depositiontemperature = 150
temperature = 150°°CC
Del
liVe
neri,
Mer
cald
o, P
rivat
o, R
en. E
nerg
y33
, 42
(200
8)
Prob
lem
with
unifo
rmity
0.8
1.0
1.2
1.4
1.6
1.8
2.0
100
101
102
103
104
105
α (cm-1)
Photon energy (eV
)
Ts= 100°C
Ts= 150°C
Ts= 220°C
PD
S
an
aly
sis
30
DecreasingH2dilution
Hydrogen dilution effect on
Hydrogen dilution effect on
µ µµµµ µµµcc-- SiSi :H:H
Th
e c
rys
tall
ine
vo
lum
e c
on
ten
to
f th
e f
ilm
sc
an
be
va
rie
d
de
pe
nd
ing
on
th
e d
ep
os
itio
nc
on
dit
ion
s.
31
Depth
Depth--
dependant
dependant
micro
micro-- Raman
Raman
analysis
analysis
Del
liVe
neri,
Mer
cald
o, T
assi
ni, Pr
ivat
o,
Thin
Solid
Film
s48
7, 1
74 (
2005
)
200
300
400
500
600
counts (a.u.)
Ram
an Shift (cm
-1)
67 Pa
107 Pa
127 Pa
200
300
400
500
600
counts (a.u.)
Ram
an Shift (cm
-1)
67 P
a 107
Pa
127
Pa
Bot
tom
illu
min
atio
n, 6
33 n
m e
xcita
tion
light
Top
illum
inat
ion,
633
nm
exc
itatio
n lig
ht
TCO
glass
i: 1.5 µm
n
bottom
top
p
514 nm
, 633
nm
180 nm
700 nm
700 nm
180 nm
Less
ord
ered
str
uctu
re in
the
fir
st s
tage
s of
the
dep
ositi
on
32
High H
2dilution:
“too
crys
talli
ne”
mat
eria
l
low
abso
rptio
nco
effic
ient
.
Lo
wH
2d
ilu
tio
n:
Lo
w q
ua
lity m
ate
ria
l w
ith
larg
e a
mo
rph
ou
s c
on
ten
t.
Inte
rme
dia
te d
ilu
tio
n:
Op
tim
alsp
ectr
alre
sp
on
se
Effic
ienc
yis
max
imiz
edw
hen
usin
gµc-
Si:H
gro
wn
in t
he a
mor
phou
s-to
-cry
stal
line
tran
sitio
nre
gion
.
Hydrogen dilution effect on
Hydrogen dilution effect on
µ µµµµ µµµcc-- SiSi :H
:H cells
cells
400
500
600
700
800
900
1000
0.0
0.2
0.4
0.6
0.8
Q.E.
Wavelenght (nm
)
H2/(SiH
4+H
2)= 97.0%
H2/(SiH
4+H
2)= 96.6%
H2/(SiH
4+H
2)= 96.4%
H2/(SiH
4+H
2)= 95.9%
Hig
h
dilu
tio
n
Lo
wd
ilutio
n
Del
liVe
neri,
Mer
cald
o, e
tal
.19t
h Eu
rope
anPh
otov
olta
icSo
lar
Ener
gyCo
nfer
ence
(Par
is),
146
9 (2
004)
Bes
t µc-
Si:H
mat
eria
lfo
rso
lar
cells
:cr
ysta
llini
tyfr
actio
nar
ound
50 -
70%
33
Effect of bottom cell on tandem device
Effect of bottom cell on tandem device
Top Cell:
Top Cell:
Top Cell:
Top Cell:
p a-SiC:H
thickne
ss: 7
nm
i a-Si:H
thickne
ss: 2
70 nm
n µc-Si:H
thickne
ss: 3
0 nm
Bottom Cell:
Bottom Cell:
Bottom Cell:
Bottom Cell:
p µc-Si:H
thickne
ss: 3
0 nm
i µc-Si:H
thickne
ss: 1.5 µm
n µc-Si:H
thickne
ss: 4
0 nm
Back contact:
Back contact:
Back contact:
Back contact:
ZnO
/Ag
ZnO/Ag
Gla
ss
TCO
blue
Sun
Sunlight
light
red
np
i
a-Si:H
pi
n
µc-Si:H
Subs
trat
e: A
sahi
U-t
ype
Cel
l Are
a: 1
cm
x 1
cm
Whe
n fa
bric
atin
g a
mic
rom
orph
tand
em s
olar
cel
l, th
e ba
sic
prob
lem
is
com
bini
ng a
hig
h-cu
rren
t bu
t lo
w-v
olta
ge m
icro
crys
talli
ne c
ell w
ith
a lo
w c
urre
nt b
ut h
igh-
volta
ge a
mor
phou
s ce
ll.
Diff
eren
t de
posi
tion
cond
ition
s fo
r i l
ayer
exp
lore
d
34
Micromorphtandemdevices
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
34567891011
η (%)
SC (%)
55606570
FF (%)
4681012
40 Pa, 12 W
40 Pa, 20 W
67 Pa, 20 W
67 Pa, 33 W
JSC (mA/cm2)
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
1.1
1.2
1.3
1.4
VOC (V)
SC (%)
0.3
W/P
a
0.5
W/P
a
At high power to pressure ratio (0.5 W/Pa) high JSC, and almost
constant FF and η ηηηin a wide SC range
The weak dependenceon SCmakes such deposition
regime very interesting for industrial application.
Del
liVe
neri,
M
erca
ldo,
et
al.
Jour
nal N
on-C
ryst
.So
lids
354,
247
8 (2
008)
.
35
Best efficiency
Technique: VHF PECVD at 100 MHz
Depositiontemperature = 150°C
Lowpower topressureratio =0.3 W/Pa
Substrate: Glass/SnO2Asahi U-type
Area: 1 cm X 1 cm
np
ip
in
270 nm
1.5
µm
a-Si
µc-Si
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
02468
10
12
14
J (mA/cm2)
V (V)
VO
C=
1.3
4 V
J SC
= 1
2.9
mA/c
m2
FF =
66
%η ηηηinitial= 11.3 %
η ηηηstabilized> 10 %
36
3540
4550
5560
65051015
∆η (%)
ΦC (%)
40 Pa, 20W
67 Pa, 20W
Stability of tandem devices
Stability of tandem devices
The
larg
e ∆
ηm
easu
red
for
the
series
dep
osite
d at
40P
a fo
r Φ
c>58
% c
an b
e du
e to
a c
urre
nt m
ism
atch
, w
ith t
he a
mor
phou
s to
p ce
ll lim
iting
the
out
put
valu
e.
Del
liVe
neri,
Mer
cald
o, e
tal
, Jou
rnal
Non
-Cry
st. S
olid
s35
4, 2
478
(200
8).
Ex
pe
rim
en
tal:
20
0 h
ou
rs o
f lig
ht-
so
ak
ing
at
op
en
-cir
cu
it u
nd
er
so
lar
sim
ula
tor
(AM
1.5
)
Rel
ativ
e ef
ficie
ncy
loss
∆η=
(ηin
itial-η
degr
aded
)/η
initi
al~
5 –
13 %
depe
ndin
gon
the
cry
stal
line
phas
efr
actio
nin
the
µc-
Sibo
ttom
laye
r
Du
e t
ob
ett
er
sta
bilit
yo
f th
e m
icro
cry
sta
llin
ec
om
po
ne
nt,
a t
an
de
m
de
vic
ew
ith
a b
ott
om
ce
llli
mit
ed
cu
rre
nt
mis
ma
tch
isp
refe
rab
lein
ord
er
tore
du
ce
th
e l
igh
t-in
du
ce
dd
eg
rad
ati
on
eff
ec
t.
37
Intermediate
Intermediate reflector
reflector
Usi
ngan
appr
opriat
e m
ater
ial
asin
term
edia
te r
efle
ctor
in b
etw
een
the
two
com
pone
ntce
lls,
itis
poss
ible
toen
hanc
eth
e ph
otoc
urre
ntof
the
top
cel
lw
ithou
tin
crea
sing
the
thic
knes
s, t
hus
impr
ovin
gal
soth
e de
vice
stab
ility
.
38
Solar
Solarcells
cellson
on flexible
flexiblesubstrate
substrate
Polymer
ZnO
P I N
Ag
De
po
sit
ion
De
po
sit
ion
tec
niq
ue
tec
niq
ue
: V
HF
PE
CV
D a
t 1
00
:
VH
F P
EC
VD
at
10
0 M
Hz
MH
z
Su
bs
tra
te:
PE
T/
Su
bs
tra
te:
PE
T/ Z
nO
Zn
O
05
10
15
00,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
J (mA/cm )2
V (
V)
Eff
= 4
.1 %
FF
= 4
9
Vo
c=
77
0 m
V
Jsc
= 1
0.7
mA
/cm
2
2
%
aa-- S
i:H
Si:
H
pp-- ii
-- n
n d
evic
ed
evic
eSm
alla
rea
39
III generation
III generation photovoltaics
photovoltaics
Acco
rdin
g to
th
e U
.S. D
oE
, fo
r P
V
be
co
min
g a
n e
ffe
ctive
so
lutio
n t
o
the
en
erg
y p
rob
lem
, th
e c
osts
sh
ou
ld r
ea
ch
th
e le
ve
l o
f
0.3
3 U
SD
/ W
Th
in F
ilm T
ech
no
log
y (
the
2n
d
Ge
ne
ratio
n P
V)
ha
s b
rou
gh
t th
e P
V
fie
ld in
a n
ew
be
tte
r re
gio
n o
f th
e
Co
st-
Eff
icie
ncy s
pa
ce
Th
e n
ew
ch
alle
ng
e fo
r th
e t
ech
nic
al a
nd
scie
ntific c
om
mu
nity
isto
de
ve
lop
a t
hir
d g
en
era
tio
n o
f th
in f
ilm
PV
wh
ich
fo
llow
s t
his
mu
ch
mo
re a
gg
ressiv
e s
lop
e (
0.3
3 U
SD
/ W
).
40
So
lar
sp
ectr
um
Th
e t
wo
mo
stim
po
rta
ntp
ow
er
loss
me
ch
an
ism
sin
sin
gle
ba
nd
ga
pso
lar
ce
llsa
rise
fro
mth
e in
ab
ility
toa
bso
rb
ph
oto
ns
with
en
erg
yle
ss
tha
nth
e
ba
nd
ga
pA
a
nd
th
erm
alis
atio
no
f
ph
oto
ne
ne
rgy
exce
ed
ing
the
ba
nd
ga
pB
.
The III generation
The III generation multijunction
multijunctionapproach
approach
Th
e id
ea
is t
o e
ng
ine
er
ne
w
ma
teri
als
with
ta
ilore
d
ba
nd
ga
p,
wh
ich
ab
so
rb p
ho
ton
s in
a
de
dic
ate
d e
ne
rgy r
an
ge
, b
y u
sin
g
the
qu
an
tum
co
nfi
ne
me
nt
eff
ect.
Eg
A
BSun
light
41
Th
e c
on
ce
pt
be
hin
d t
his
inn
ova
tive
de
vic
e is
th
e
va
ria
tio
n o
f th
e b
an
d g
ap
wit
h t
he
siz
e o
f q
ua
ntu
m
do
ts a
nd
th
e c
on
tem
po
rary
hig
he
r e
ffic
ien
t a
bs
orp
tio
n o
f
the
so
lar
sp
ec
tru
m in
na
no
str
uc
ture
s.
All
All SiSiquantum dot solar cell
quantum dot solar cell
prof
. M
. G
reen
(U
NSW
, Aus
tral
ia)
dots
Our
idea
: fin
da
subs
titut
efo
ra-
Si:H
in t
hin
film
tan
dem
dev
ices
Si Q
Ds
in
die
lectr
ic
ma
trix
42
Si Q
Ds
SiN
xm
atrix
PECVD in
PECVD in situ
situgrowth
growthof Si
of Si QDs
QDsin
in SiNSiN
xx
T.-W
. Kim
et
al.,
Appl
. Phy
s. L
ett.
88 (
2006
) 12
3102
Inho
mog
eneo
us g
row
th is
pr
omot
ed in
low
rat
e re
gim
e by
fo
rmat
ion
of S
idan
glin
g bo
nds
actin
g as
nuc
leat
ion
site
s.A
lo
we
r b
arr
ier
he
igh
t b
etw
ee
n a
dja
ce
nt
qu
an
tum
do
ts,
su
ch
as w
ith
sili
co
n n
itri
de
inste
ad
of
sili
co
n o
xid
e,
en
ha
nce
s c
arr
ier
tun
ne
llin
g a
nd
la
rge
r in
terd
ot
dis
tan
ce
ca
n b
e a
llow
ed
.
Tra
ns
po
rt p
rop
ert
ies
will
de
pe
nd
als
o o
n t
he
ma
trix
.
De
po
sitio
nte
mp
era
ture
≤3
00
°C
NO
PO
ST
AN
NE
AL
ING
43
ENEA
ENEA results
results: room temperature PL
: room temperature PL
400
500
600
700
800
900
0.0
0.2
0.4
0.6
0.8
1.0
Normalized PL Intensity
Wavelength (nm)
increasing
N2 flow
rate
400
500
600
700
800
900
1.5 sccm
3 sccm
9 sccm
5 sccm
7 sccm
PL intensity (a.u.)
Wavelength (nm)
vary
ing
NH
3flo
w r
ate
Samples grown with SiH
4and N
2
SiNx
Si In
cre
asin
gN
2o
r N
H3
flo
wra
te
L.V.
Mer
cald
oet
al.,
subm
itted
toM
at. S
cien
cean
d En
gine
erin
gB
(2 p
aper
s).
Samples grown with SiH
4and NH3diluted in N
2
44
400
500
600
700
800
900
NH3- type
sample
PL intensity (a.u.)
Wav
elen
gth (nm)
N2- type
sample
ENEA
ENEA results
results(2)
(2)
Com
pariso
nof
sam
ples
with
max
PL
inte
nsity
with
inea
chse
ries
The
extr
a hy
drog
en a
vaila
ble
in N
H3
type
sam
ples
m
ore
effic
ient
ly p
assi
vate
sno
nrad
iativ
ede
fect
ce
nter
sat
the
dot
-mat
rix
inte
rfac
e.
12
34
56
102
103
104
105
106
n ~ 2.3
E
PL
~ 1.9 eV
Si 3N
4
NH3-type
N2-type
re
fere
nce
d
ata
α (cm-1)
Energy (eV)
a-Si:H
E
PL
~ 2.35 eV
n ~ 2.0
Abs
orpt
ion
spec
tra
Pre
se
nce
of str
on
gly
ab
so
rbin
gS
i
reg
ion
se
nh
an
ce
sth
e lo
we
ne
rgy
op
tica
la
bso
rptio
n.
L.V.
Mer
cald
oet
al.,
subm
itted
toM
at. S
cien
cean
d En
gine
erin
gB
45
ENEA activities on thin film silicon solar cells
ENEA activities on thin film silicon solar cells
Development of transparent and conductive oxide (TCO) films
Development of transparent and conductive oxide (TCO) films
Tandem
Tandem ““micromorph
micromorph””solar cells
solar cells
Solar devices on polymeric substrates
Solar devices on polymeric substrates
Third generation approaches
Third generation approaches
Than
ks f
or y
our
atte
ntio
nTh
anks
for
you
r at
tent
ion
Lucia Vittoria Mercaldo
ENEA –PorticiResearch Center
Energy Technologies, Efficiency
and Renewable Sources Department
Photovoltaic Technologies Section (TER-ENE-FOTO)
e-mail:
luci
a.m
erca
ldo@
port
ici.e
nea.
it
www.ene1.portici.enea.it
NIS
Col
loqu
im, T
orin
o Ju
ne23
, 200
8
