The Structure Design And Stability Of Large-scale Dye-sensitized Solar Cells

The Structure Design and Stability of Large-Scale Dye-Sensitized Solar Cells

Songyuan Dai Key Lab of Novel Thin Film Solar Cells, Chinese Academy of Sciences, Hefei, Anhui, P. R. China

Where is ASIPP located ? Anhui Province

ASIPP

Hefei City Key Lab of Novel Thin Film Solar Cells, CAS

ASIPP

ASIPP

ISP

HIPCAS IIM OFMI

Key Lab of Novel Thin Film Solar Cells, CAS

Chinese Academy of Sciences

BCAS ★ CAS

BCAS

BCAS

1000km BCAS BCAS IPP BCAS BCAS 500km BCAS BCAS BCAS BCAS BCAS

BCAS Key Lab of Novel Thin Film Solar Cells, CAS

How did we start ? 

Collaboration agreement with STA in Apr. 1997



Project funded by Worldlab in 1996~2006



Collaborate with M. Grätzel

1997.04 1999.03

Key Lab of Novel Thin Film Solar Cells, CAS

Key Lab of Novel Thin Film Solar Cells, CAS

Institute of Plasma Physics, Chinese Academy of Sciences

500W DSC primary power station

2004.10.14

Key Lab of Novel Thin Film Solar Cells, CAS

2004.10

2007.09.05 The design and outdoor application of dye-sensitized solar cells, Songyuan Dai, etc., Inorganica Chimica Acta 361 (2008) 786–791 Key Lab of Novel Thin Film Solar Cells, CAS

Outline 



Simulation and Structure design of large-scale DSC Stability research of DSC modules Key Lab of Novel Thin Film Solar Cells, CAS

How to achieve Pmax for a TCO glass  High

active area ?  Less resistance loss ?  Best Sealing strength ?  Anti-corrosion ?  Life-time is preferred!

Key Lab of Novel Thin Film Solar Cells, CAS

The problems to enlarge size of DSC

Current density/mA· cm

-2

TCO:15Ω/□ 0.8cm×0.8cm

15 12 9 6

2cm×2cm

3 0 0.0

0.2

0.4

0.6

Voltage/V Jsc

FF

Square Resistance: RTCO Electron Collection: H Key Lab of Novel Thin Film Solar Cells, CAS

Improvement by silver grid TCO:15Ω/□

Silver grid

• Isc and FF are increased When used silver grid. • But FF is lower still than Small-scale cell, why? • The resistance of silver must be taken into account in large-scale Cell.

cell area: 0.7cm×18cm， resistance of silver grid: 0.8Ω Key Lab of Novel Thin Film Solar Cells, CAS

Theoretical simulations of Matlab : Different active area

TCO:15Ω/□

The larger active area, the more lower FF of DSC! Key Lab of Novel Thin Film Solar Cells, CAS

What we do? 1.The lower fill factor and efficiency for large scale DSC; 2.By introducing silver grid, fill factor and efficiency improved obviously; 3.We need: Theoretical simulations and Structure design! Key Lab of Novel Thin Film Solar Cells, CAS

Electron diffusion continuity equations: Main recombination :

I3- + 2e-(cb) → 3I-

 2 nx  nx   n0  x Dn     e 0 2 x  boundary conditions:

n x

xd

0

Dn

n x

x 0

 kext ( n  n0 )

 Ln 2 I 0 exp( x)  n0  C1 exp( x / Ln )  C2 exp( x / Ln ) n( x )  2 2 D(1   Ln ) Photocurrent and photovoltage:

J photo

dn  eD dx

V photo x 0

k BT n( x  0) ln  q n0 Key Lab of Novel Thin Film Solar Cells, CAS

Design scheme of strip cell J   ( x)    t 2

W1: the width between Silver grids W : the width of TiO2 films W2: the width of silver grid Sb : the distance from TiO2 films to silver grid l

: the length of TiO2 films Key Lab of Novel Thin Film Solar Cells, CAS

Assumptions and boundary conditions: Y

1、The thickness of TCO is enough thinner than the size of cell

TCO

 Jx  Jy  0 Z Z

TiO2/dye

2、The photocurrent is uniform in the region of TiO2/dye

Jz ( Z  d )  J e

e

3、The resistivity of silver grid is enough smaller than the resistivity of TCO

Z



Ag

 

0

4、electric current is Ohm style in TCO Silver grid

X ρ: resistivity of TCO σ: conductivity of TCO d : thickness of TCO

J  E

Key Lab of Novel Thin Film Solar Cells, CAS

Application of Laplace equation:   E ( x, y, z )  0  2    ( x, y , z )  0   E ( x, y, z )     J        2  2  0  2  2   2   2 d x y z x y z 2

2

2

2

2

2

2 J J 1 2 2  0  2       ( x  c1x  c2 ) 2 x d d 2 y Boundary condition 3:

J 1 2 1    ( x  W1x) d 2 2 Key Lab of Novel Thin Film Solar Cells, CAS

Calculation and simulation results: 1. The loss of electrons transfer through silver grid: PAg   I  dR 2

2

L





[ J W  ( L  y )]  dR  ( J W  l ) 2 

L l

 Ag ( L  l ) h W2

2. The loss of electrons on contact resistance: 2

l



Pcon   I  dR  [ JWdy ]  2

0

c W2  dy

3. The loss of electrons transport through TCO: PTCO   dI U

W1 /2

 4{



Sb

1 Jl dx    [ Jl W   ]} 2 Key Lab of Novel Thin Film Solar Cells, CAS

Simulation results

1. FF depended on silver grid resistance Size: 0.7cm ×18cm

Silver grid

With the increase of silver resistance, FF decrease obviously! Key Lab of Novel Thin Film Solar Cells, CAS

Simulation results

2. Efficiency depended on silver grid resistance initial parameters: L=19cm， l=18cm， Sb=0.1cm， W2=0.2cm， ρAg=3×10-6Ω·cm， ρc=0.01Ω·cm2 RTCO=15Ω/□

Different illumination intensity: 100mW/cm2, 50mW/cm2, 20mW/cm2

I0=1.0×1017 cm-2s-1， ηinj=99.9%， α=5000 cm-1， d=10-3cm， D=10-4 cm-2s-1， T=300K， τ=10-2s， no=104

Key Lab of Novel Thin Film Solar Cells, CAS

Simulation results

2.Efficiency depended on contact resistance

L=19cm，l=18cm，Sb=0.1cm，W2=0.2cm，ρAg=3×10-6Ω·cm，RTCO=15Ω/□ I0=1.0×1017 cm-2s-1，ηinj=99.9%，α=5000 cm-1，d=10-3cm，D=10-4 cm-2s-1， T=300K，τ=10-2s，no=104。

Key Lab of Novel Thin Film Solar Cells, CAS

Simulation results

3.The width of TiO2 films Width

L=19cm，l=18cm，Sb=0.15cm, W2=0.1cm，ρAg=3×10-6Ω·cm. Key Lab of Novel Thin Film Solar Cells, CAS

Simulation results

3.The width of TiO2 films I0=1.38×10 cm-2s-1， ηinj=99.9%， α=5000 cm-1， d=10-3cm， D=10-4 cm-2s-1， T=300K， τ=10-2s， no=104。 L=19cm，l=18cm， Sb=0.1cm，W2=0.2cm， ρAg=3×10-6Ω·cm， ρc=0.01Ω·cm2， h=0.001cm， RTCO=15Ω/□

Key Lab of Novel Thin Film Solar Cells, CAS

Parallel Module Design in IPP

Key Lab of Novel Thin Film Solar Cells, CAS

Module Design We wish to: total output power (Pmax)

By: loss in TCO and silver grid active area

Active area: WX×LT×N/total area Key Lab of Novel Thin Film Solar Cells, CAS

Parallel Module Design

Optimum width:7mm Active area:62%

Sun=100mW/cm2, RTCO=15 Ω/□, Wm=0.1 cm, Lm=19 cm, Rm=0.4Ω Key Lab of Novel Thin Film Solar Cells, CAS

Power depended on illumination intensity The high resistivity of TCO leads to a lower optimal width, and the output power reduces rapidly under the strong light. Wider optimal widths are obtained with TCO sheet resistance is 8 Ω/□. The optimal width from 7 mm to 10 mm under different illumination intensity .

Wm=0.1 cm, Lm=19 cm, Rm=0.4Ω

Key Lab of Novel Thin Film Solar Cells, CAS

Large-scale DSC based on structure design

Key Lab of Novel Thin Film Solar Cells, CAS

Next goal:  Give

your glass, give me best achieve in one year.

Key Lab of Novel Thin Film Solar Cells, CAS





Simulation and Structure design of large-scale DSC Stability research of DSC modules

Key Lab of Novel Thin Film Solar Cells, CAS

Indoor aging test system UV

Vis

2 KW

Key Lab of Novel Thin Film Solar Cells, CAS

Outdoor aging test system Out-door real-time test system

Key Lab of Novel Thin Film Solar Cells, CAS

The Stability for DSC under UV in different band

393 nm is better!

Time-course change of the normalized photovoltaic performance of DSC. Key Lab of Novel Thin Film Solar Cells, CAS

Stability research by electrochemical methods TiO2

Main origin

Pt Rh

Resistance of TCO

Z1 (R1, C1)

Electrolyte/CE

Z2 (R2, C2)

TiO2/Dye/Electrolyte

Z3 (R3, C3)

Diffusion in the Electrolyte R2

R1

-2 (Ω) Z"

Z3

Rh C1

Z2

-1

Z1

10 Hz

Z3 1 kHz

100 kHz

C2

0.1 Hz

0 0

Rh

1

R1

2

R2 3 Z' (Ω)

R3 4

5

Key Lab of Novel Thin Film Solar Cells, CAS

Stability Results

Stability data of device parameter variations for DSC (measured under 1 sun) of 4 cm² cells on master plates aged with a UV-light tester at 50 ºC).

After a short decrease, Jsc and Eff almost keep constant! Key Lab of Novel Thin Film Solar Cells, CAS

Stability research by electrochemical methods Z2 (R2, C2)

TiO2/Dye/Electrolyte

Z2

R2 TiO2

Pt

The slightly decreased R2 orτ for recombination reaction of the working electrode after aging with a UV-light tester lead to a gradually small decrease in Voc . Key Lab of Novel Thin Film Solar Cells, CAS

Showcase still running(2004.10.15~???)

Key Lab of Novel Thin Film Solar Cells, CAS

Key Lab of Novel Thin Film Solar Cells, CAS