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Basic research in fabrication CIGS solar cellsBasic research in fabrication CIGS solar cellsHao Xu, Fang LuHao Xu, Fang Lu
Department of Physics, Fudan University, Shanghai 200433, ChinaDepartment of Physics, Fudan University, Shanghai 200433, China
•Grid Al•ZnO:Al(200~400nm)•i-ZnO(80~100nm)•CdS(50nm)•CuIn0.7Ga0.3Se2(1~2μm)•Mo(0.5~1μm)•Sola-lime glass (SLG)
30 40 50 60 70
Dst=7cm
Dst=6cm
Dst=4.5cm
Rel
ativ
e In
tens
ity
2(deg)
(a)
526 528 530 532 534 536 5380
20000
40000
60000
80000
100000
O1s
Cou
nt
Binding energy (eV)
(a)
1018 1020 1022 1024 1026 10280
50000
100000
150000
200000
250000
300000
350000
Zn 2
p3/2
Cou
nt
Binding energy (eV)
(b)
200 300 400 500 600 700 800 9000
20
40
60
80
100
Tran
smitt
ance
(%T)
Wavelength (nm)
4.5cm 6cm 7cm
(a)
3.0 3.2 3.4 3.6 3.80.00E+000
5.00E+009
1.00E+010
1.50E+010
2.00E+010
(cm
-2)
Photon Energy (eV)
4.5cm 6cm 7cm
(b)
1E19 1E20 1E210
25
50
75
100
M
obili
ty (c
m2 V
-1s-1
)
Concentration (cm-3)
1.0m
cm
0.5m
cm
100 101 102 10310-4
10-3
Res
istiv
ity
(cm
)
Exposure Time (h)
AZO(1%) SAZO(1%,1%) AZO(2%) SAZO(2%,0.5%)
Homogeneous process Cd(CH3COO)2→Cd2++2CH3COO-
CS(NH2)2+OH-→SH-+CH2N2+H2O SH-+OH- →S2-+H2O Cd2++S2- →CdS↓ Heterogeneous process NH4++OH-↔NH3+H2O Cd2++4NH3 ↔Cd(NH3)4
2+
5 6 710-4
10-3
10-2
1020
1021
0
10
20
30 Resistivity
Res
istiv
ity (
.cm
)
Distance (cm)
Concentration
Con
cent
ratio
n (c
m-3)
Mobility
Mob
ility
(cm
2 V-1s-1
)
2 Chemical bath deposition (CdS buffer layer)
1 RF Magnetron Sputtering (AZO buffer layer)
Small, compact CdS grain (50~100nm)
22
11
1
minmaxmin )/(1)/(1
nnnn refrefM
)8
exp(.2
)/exp(.
0
22
*
0
NkTQe
kTm
eL
kTE
t
bS
Semi-empirical model in ZnO single crystal presented by Masetti
Grain boundary scattering limited transport model of Seto
Resistivity stability of window layer can be improved by doping Si impurity
gEh 2teII 0
High conductivity and optical transmittance in visible region, non-toxicity, low cost, material abundance, relatively low deposition temperature, and high stability.
Burstein-Moss shift of the absorption edge
SM 111
Combined model in AZO films
Only strong (002) peak is observed in XRD, which indicates a hexagonal wurtzite structure.XPS show stoichiometric and non- stoichiometric atomic ratio of O/Zn in different deposition distances.
1. Complete coverage of the rough absorber surface2. Remove natural oxide from film surface3. Passivate CIGS surface to prevent surface inversion4. Protect CIGS from subsequent ZnO sputtering
Advantages of CBD
Introduction
CuIn0.7Ga0.3Se2 (CIGS) based solar cell is one of the most promising thin films solar cells. Its advantages include less amount materials, light mass, high radiation hardness and highest conversion efficiency in single-junction solar cell.
Structure
0 1000 2000 3000 4000
0
500
1000
1500
2000
2500
3000
3500
Sur
face
Rou
ghne
ss (n
m)
Distance (m)
3 Laser surface anealing and C-V
The roughness in absorber lead to short circuit of solar cell. A beam of unfocused laser was introduced to melt and smooth surface.
ArAr
D
qNAV
qNAV
C 02
022
221
Plot of 1/C2 vs. V, yielding NA =2×1015 cm-3 and build-in field VD=0.894V.
-0.6 -0.4 -0.2 0.030
40
50
Cap
acita
nce
(pF)
Reversed Bias (V)
300K
270K
200K