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LOGOwww.themegallery.com
www.ssu.ac.kr
태양전지 원리-고체전자론 개론
nonrenewable energy renewable energy
Total global energy
Consumption 1.0 1010 kW
0.1% of total earth surface solar cells with 10% efficiency
Importance of Solar Energy Utilization
Total solar radiation falling on the earth
1.2 1014 kW (10,000 times consumption)
1. SPACE TECHNOLOGY
4. REMOTE POWER
3. BATTERY RECHARGING
2. VEHICLES
태양전지 응용 분야
5. LIGHTING
7. RESIDENTIAL ELECTRICITY
6. MILITARY
8. PORTABLE POWER
http://21st-century-goods.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=21st&Product_Code=PS9700&Category_Code=SPT
How does it work?
1. Light Absorption
Conversion of into Electricity
2. Charge Separation
3. Charge Collection
What is Solar cell?
Inorganic pnJunction Solar Cell
n-type
semiconductorp-type
semiconductor
h+
e–
ECB
EVB
Si, CIS, CdTeEfficiency: very high
Cost: very high
Anode
Conjugated Polymer Solar Cell
Electron
acceptor
Hole
acceptor
Cathode
HOMO
HOMO
LUMO
LUMO
h+
e–
e–
C60, PolymersEfficiency: low
Cost: low
Dye-Sensitized Solar Cell
Redox
electrolyte
e–
e–
h+
A–
A
Dye-adsorbed
n-type
semiconductor Metal
Dye-TiO2Efficiency: high
Cost: low
Type of solar cell
Nanocrystalline Oxides
Dye
Redox Couple& Hole Conduxtors
Transparent Conductive Materials
Counter Electrode
Materials for DSSC
N
N
C
C
O
O
HO
N
N
C
C
O
O
O
HO
RuNCS
NCS
O
e–
Pt-coated glass
I- / I2electrolyte
Dye/TiO2 layer (10 – 15 m)
SnO2-basedTCO-
+
inter-connection
DSSC Structrure
TiO2/Dye/liquid junction
EVB
ECB
A-
A
e–e–
h+
TiO2/liquid junction
metalTiO2
load
n-SC
(TiO2)
CB
VB
EF
e–
e–
e–
(D+/ D)
(D+/ D*)
(I3¯ / I¯)
Voce–
load
PtTCO
E
dye redox
electrolyte
e–
e–
UV
Visible
Role of Dye Molecules
1 cm
6 cm2
1 cm
1 cm
0.5 cm
0.5 cm
0.5 cm12 cm2
1.5 cm2
0.25 cm0.25 cm
0.25 cm
8 8 0.375/cell 64 = 24 cm2
Surface area = (1/2)n-1 6 (8)n-1
Nanotechnology
How to increase amount of dye → by increase of surface area
DSSC: Operation PrincipleAnode:
D + hν → D* absorption
D* → D+ + e- (TiO2) injection
2D+ + 3I- → 2D + I3- regeneration
Cathode:
I3- + 2e- (Pt) → 3I-
Cell:
e-(Pt) + hν → e- (TiO2)
D*/D+
D/D+
CB
VB
I3¯/I¯
surface states
Voc
TiO2 Dye
inj
cc
r
투명전극
전자전달 불리
전자전달 용이
Nanoparticle Network: Interconnection?
“shuttle”
I-
I3-
염료
Pt
= 전자
TiO2
Ion Transport in Redox Electrolyte
J. Ferber et al., Solar Energy Materials and Solar Cells, 53, (1998) 29
Total reaction: 2-electron reaction
3I- I3- + 2e-
Successive reaction
(I- I + e-)2 charge-transfer reaction
2 I I2 fast chemical reaction
I2 + I- I3
- fast chemical reaction* Two fast reactions are in equilibrium
Mass action law
nI(x) = K1 nI3-1/2(x) nI-
-1/2(x)
Ion transport in Redox electrolyte
J
V
Maximum power rectangle
Jsc
VocVmax
Jmax
input
ocsc
input
maxmax
input
output
PFF
P
PP
VJ
VJ
Fill Factor
(FF)
ocscVJ
Measurement of Conversion Efficiency
TiO2Anatase, Rutile, Brookite
SnO2, ZnO …
200 C
240 C0.0 0.2 0.4 0.6 0.8
0
2
4
6
8
10
12
14
16
200 oC
220 oC
240 oC
Ph
oto
cu
rren
t d
en
sit
y (
mA
/cm
2)
Voltage (V)
Voc (V) Jsc (mA/cm2) FF (%) (%)
200 C 0.733 13.5 62.9 6.24
220 C 0.729 15.1 63.4 6.97
240 C 0.739 12.9 61.1 5.82
Hydrothermal Temperature of TiO2 Nanoparticle
Voltage (mV)
0 100 200 300 400 500 600 700 800
Cu
rre
nt
de
ns
ity
(m
A/c
m2)
0
2
4
6
8
10
12
14
16
Rutile (11.5 m)
Anatase (11.5 m)
Jsc (mA/cm2)
10-4 10-3 10-2
Dn (
cm
2/s
)10-6
10-5
10-4
10-3
Rutile (11.5 m)
Anatase (11.5 m)
N.-G. Park, et. al, J. Phys. Chem. B, 104, 8989 (2000): citation 65
Anatase vs. Rutile TiO2
52%
D | P – 0.76 | 0.82
Benkstein, K. D.; Kopidakis, N.; van de Lagemaat, J.; Frank, A. J.; J. Phys. Chem. B. 107 (2003) 7759
71%
Network Geometry vs Electron Transport
Nakade, S & Yanagida, S. et al;J. Phys. Chem. B. ; 2003; 107(33); 8607-8611
* Diffusion coefficient D increases and recombination rate decreases with
the increase of the particle size from 14 nm to 19 nm and up to 32 nm.
14 nm 19 nm
32 nm
IMPS
IMVS
Particle Size vs Electron Transport
Jörg Ferber and Joachim Luther,
Solar Energy Materials and Solar Cells, Volume 54, Issues 1-4 , 13 July 1998, Pages 265-275
Binary Mixture: Theoretical Calculation
Matt Law, Lori E. Greene, Justin C. Johnson, Richard Saykally, Peidong Yang
Nature Materials 4, 455-459 (01 Jun 2005)
5 m
0.5 m 50 nm
I-V
e- injection: mid-IR transientnp: nanoparticle, nw: nanowire
ZnO Nanowire for DSSC
Nano Lett. 3, 4, 555-560 (2003)
anatase
TiO2/PVP TiO2
0.025 g/ml Ti(OR)4 0.15 g/ml Ti(OR)4
쉽게 날라감
←Beads 多
전기방사 조건 SEM images
나노파이버전극
제일 가는 파이버= 54nm
PVP concentration
高低
Diameter
Beads and aggregations
少
細
多
太
PPV : 0.35-0.50 g
Ti-OR4 : 1.5ml
acetic acid : 3ml
ethanol : 10ml
PPV : 0.45 g
22-gauge needle
0.3 ml/h
2 kV/cm
600 ℃ for 3h
내 실험
최적 조건?
Materials Letters 62, 29, 4470-4472 (2008)
Electro spinning method (TiO2 fiber)
Synthetic Materials 155, 635-638 (2005)
Immersing into a 0.1M TiCl4 (24h)
(a) : TiO2
(b) : TiCl4 treatment
R : rutile peak
(a) : TiO2
(b) : TiCl4 treatment
(a) : TiO2 (with liquid electrolytes)
(b) : TiO2 (with liquid gel)
(c) : TiCl4 treatment (with liquid electrolytes)
(d) : TiCl4 treatment (with gel electrolytes)
SEM & XRD 성능 평가
TiCl4 treatment
Synthetic Metals 153, 77-80 (2005)
(a): without vapor treatment
(b): with vapor treatment
(c): after calcination without vapor treatment
(d): after calcination with vapor treatment
before calcination after calcination
Fiber structure!!
PVAc film이 fiber위에 형성.
PVAc/TiO2 전기방사 후,THF vapor하에서 1사간.
η = 4.01 %
η = 3.80 %
(a) : with liquid electrolytes
(b) : with gel electrolytesanatase
Vapor treatment (SEM & TEM)
XRD & I-V curve
Vapor treatment
Journal of Macromolecular Science, Part A : Pure and Applied Chemistry 42, 1529-1540 (2005)
PS : powder pattern
PMMA : powder pattern
PVAc : Fiber structure
SEM TEM
TEM
TEM
SEM
SEM
(a)(c): TiO2 nanofiber without vapor treatment
(b)(d): TiO2 nanofiber with vapor treatment
η = 4.01 %
η = 3.80 %
(a) : with liquid electrolytes
(b) : with gel electrolytes
SEM & TEMVapor
treatment
효율
Various support polymer
DSSC실험에 있어서 필요한 결론 :STL은 fiber와 glass의 접착력을 향상시킨다.
문제점 (소결후)1. Shrinking effect2. poor adhesion
without STL
with STL
under various electrospinning time
STL : surface treatment layer
Diluted 방사액 (1:5 in ethanol)을 사용Spin coating (1300rpm, 10s)
Drying on the hotplate (75℃)
Device A : FTO/d-TiO2/STL/P3HT/Au/Ag
Device B : FTO/d-TiO2/STL/TiO2 nanofiber/
P3HT/Au/Ag
Device C : FTO/d-TiO2/STL/TiO2 nanofiber/
N719/P3HT/Au/Ag
Device D : FTO/d-TiO2/STL/TiO2 nanofiber/
TiCl4 treatment/N719/P3HT/Au/Ag
Contact angle : 5°
= P3HT on TiO2 nanofiber
Contact angle : 22°
= P3HT on TiO2 nanoparticle
Appl. Phys. Lett. 93, 013102 (2008)
Surface treatment layer
290 ±90nm 150 ±60nm
TiCl4 treatment
Surface treatment
layer
PVP/TiO2 TiO2
anatase
Nanotechnology 18, 365709 (2007)
Spray method
Journal of Physics : Conference Series 61, 1112-1116 (2007)
0 wt.% nanowire
100wt.% nanowire
10wt.% nanowire
SEM & XRD
I-V curve & 효율
Nanowire & Nanoparticle
Narukuni Hirata, Jean-Jacques Lagref, Dr. Emilio J. Palomares, Dr., James R. Durrant, Dr.,
M. Khaja Nazeeruddin, Dr., Michael Gratzel, Prof., Davide Di Censo, Chemistry - A
European Journal, Volume 10, Issue 3, Pages 595-602 (2004)
TiO2
N719
pico-seconds
0.85 ms
Suppression of Recombination from TiO2 to Dye: Supramolecular Approach
TCOTiO2
Ru
N
N
-OOC
-OOC
NCSNCS
N
N
Ru
N
N
-OOC
-OOC
NCSNCS
N
N
I3-/I-
e-
X
S. M. Zakeeruddin, M. Gratzel et al., Langmuir; 2002; 18(3); 952
TiO2/Dye/Electrolyte Interface Engineering
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