染料敏化光驅動電池

台灣大學化學工程學系 何國川

E-mail: [email protected] Tel: (02) 2366-0739

10-26-2016

染料敏化光驅動電池(DSC)技術

 Introduction

 Solar Cells Progress

 Dye-Sensitized Solar Cells (DSC)

 Mechanism

 Fabrication & Measurement

 Research Fields of DSCs

 Photoanode

 Counter Electrode

 Electrolyte

 Conclusion ₁

Outline

Introduction: Progress

2









1839: Photovoltaic effect

Photovoltaic effect was first recognized by French physicist A.E. Becquerel.

1883: First Solar Cell (Efficiency: 1%)

First solar cell was built by Charles Fritts, who coated the semiconductor selenium with an extremely thin layer of gold to form the junctions (1% efficient).

1946: Junction Semiconductor Solar Cell

Russell Ohl patented the modern junction semiconductor solar cell, which was discovered while working on the series of advances that would lead to the transistor.

1954: First practical Solar Cell (Efficiency: 6%)

Bell Laboratories, experimenting with semiconductors, accidentally found that silicon doped with certain impurities was very sensitive to light.

Current

The solar cell (or photovoltaic device) fulfills two fundamental functions:

1. Photogeneration of charge carriers (electrons and holes) in a light-absorbing material.

2. Separation of the charge carriers to a conductive contact to transmit electricity.

Silicon-based solar cell

3 Thin-film (CIGS)

solar cell

Dye-sensitized solar cell

Perovskite solar cell

Origin of solar cell (photovoltaic device)

＊First Generation

G I G II G III G IV

＊ Second Generation ＊Third Generation

Photoelectrochemical cell (PEC)

Polymer solar cell

Dye-sensitized solar cell (DSC)

＊ Fourth Generation

Not commercially available yet

a-Si solar cell c-Si solar cell

poly-Si solar cell

CIGS solar cell Polymer solar cell Dye-sensitized solar cell

The Ultimate Goal ：

Maximize !

Efficiency Cost × Life

Perovskite cellsolar

cell

4

Types of solar cells in view of manufactures

Single-crystal silicon wafers (c-Si)

Single-crystalline process, High efficiency & High cost

Thin-film process, Less raw material & Flexible

Amorphous silicon (a-Si)

Polycrystalline silicon

(poly-Si)

Cadmium telluride (CdTe)

Copper indium gallium

diselenide (CIGS) alloy

Without p-n junction, Lowest cost & Flexible

Inorganic quantum dot within a polymer matrix, More effective charge transport & Low cost

5 Best Cell Research Efficiencies, National Renewable Laboratories, DOE, USA, Updated 14 Sep. 2016

Progress in cell efficiency worldwide

7

 Progress of DSCs

1) Gerischer et al., 1968: on flat electrode, very poor efficiency 2) Tsubomura et al., 1976: ZnO, at 563 nm, 2.5%

3) Grätzel, 1991: TiO

, at AM1.5, 7.12%

4) C. G. Wu & Grätzel, 2009: TiO

, at AM1.5, CYC-B11,~11.5%

5) Grätzel, 2014: TiO

, at AM1.5, Cobalt-based DSSC, 13%

6) Yano & Hanaya, 2015: TiO

, at AM1.5, ADEKA-1 & LEG4 14.3%

 Why DSCs?

6

Progress of DSCs

 Dye-Sensitized Solar Cells

 Advantages:

1. Low-cost manufacture

2. Portable and flexible product 3. Broad spectral absorption range

 Disadvantages:

1. Efficiencies are much lower than that of perovskite solar cells (22.1%).

2. Degradation effects: efficiency is decreased over time due to environmental effects.

7

New generation: dye-sensitized solar cells

8

From 70 to 7 g/W

Applications of solar cells

DSCs: Mechanism

9

Dye-sensitized TiO

electrode

e

Pt CE

S/S

S*

I

I

Sensitizer

Electrolyte

redox mediator TiO

|S + hν→ TiO

|S*

TiO

|S* → TiO

|S

+ e

TiO

|S

+ e

→ TiO

|S

TiO

|S

+ 3/2 I

→ TiO

|S +1/2 I

1/2 I

+ e

→3/2 I

I

+ 2e

→3 I













10

DSCs: mechanism

Inorg. Chem. , 44, 20, 6845 (2005)

Electron injection

Dye regeneration

Conducting Glass (TCO)

Counter Electrode

(Pt)

solution

- -

Redox Electrolyte

(I₃ /I )

11

Dynamic competition in DSCs

DSCs:

Fabrication & Measurement

12

13

Fabrication processes of the DSC

14

Instruments: Solar simulator

  J

V

 FF p

i

Max. power

V

max. power FF 

J

V

Acc. Chem. Res. 33, 269, 2000.

 Under solar light illumination, sweep voltage from -0.1 to 0.8 V, and read the corresponding current.

potentiostat &

galvanostat Solar simulator

15

I-V property analysis

 IPCE: Incident photon to current conversion efficiency

 To get a wavelength-resolved IPCE diagram

Light Source

Monochromator

Water filter

Power detector

16

Incident photon to current conversion efficiencies

(IPCE) measurement

ψ

LHE(λ) η

Dye, N719

IPCE(λ)

Wavelength (nm)

e

e

e

 LHE(λ) : Light-Harvesting Efficiency for photons of wavelength λ

 ψ

inj

: Quantum yield for electron injection from the excited dye to conduction band of TiO

 η

: Electron collection efficiency

The monochromatic photon flux that strikes the cell

Photon flux

IPCE(λ) = LHE(λ)ψ _inj η _coll

Inorg. Chem ., 44, 20, 6845 (2005)

17

The number of electrons measured as photocurrent in the external circuit

Incident photon to current conversion efficiencies

C. R. Chimie., 9, 645 (2006) RR_ss

RR_cctt11

C CPE1P E1

ZZ_ww RR_cctt22

C CPE2P E2 RRR_Sss

RRR_Cccttt¹¹1

CPE^CC PE1PE1 1

ZZZ_Www RRR_Cccttt²²²

CPE^CCP E2PE22 RRRRR_Sssss

RRRRR_Cccccttttt¹¹¹¹1

CPE^CCCC PE1PE1 PE1PE1 1

RZZZZ_dwwwwiff RRRRR_Cccccttttt²²²²²

CPE^CCCCP E2PE2P E2PE22 RRRRR_Sssss

RRRRR_Cccccttttt¹¹¹¹1

CPE^CCCC PE1PE1 PE1PE1 1

ZZZZZ_Wwwww RRRRR_Cccccttttt²²²²²

CPE^CCCCP E2PE2P E2PE22 R_S

CPE1

R_Ct1 R_Ct2

CPE2 R _diff

R

R

R

R

R

: ohmic serial resistance

R

: charge transfer resistance at electrolyte/counter electrode R

: charge transfer resistance at TiO

/dye/electrolyte

R

: Warburg diffusion resistance of I

/I

in the electrolyte

Photoanode

Counter Electrode

18

Electrochemical impedance spectra (EIS)

Electrochemical methods: fundamentals and applications, 2nd ed., John Wiley & Sons, New York (2001)

19

Rotating disc electrode (RDE)

Research Fields of DSCs:

Photoanode

20

Photoanodes

Semiconductor film

TiO ₂ ZnO Dye

Ru-dye

Organic dye

21

Working electrodes

Photoanodes Dye

Ru-dye

Organic dye

22

Working electrodes

Ruthenium Dyes

J. Phys. Chem. B, 107, 8981 (2003)

23

Organic Dyes

Dye 1: D149

J. AM. CHEM. SOC., 126, 12218 (2004) Dye 1: D149

24

Photoanodes

Semiconductor film

TiO ₂ ZnO

25

Working electrodes

Structures

Dumbbell Hexagonal plates

Rods Clubs

Intergrowth Clubs Coral Circle plates Needle

 ZnO

 TiO

Micro-pore cluster _Tubes

26

Structures

27

Science, 293, 269 (2001) TiO₂/MWCNTs film

Sol. Energy Mater. Sol. Cells 92, 1628 (2008)

Doping

28

 Plastic

J. Power Sources, 195, 4344 (2010)

 Metal foil

J. Electrochem. Soc., 154, A455 (2007)

Flexible substrates

29

Plastic/ITO based TiO

photoanode

Using compression method

J. Power Sources 195 , 6225 (2010)

Plastic-based flexible DSCs

30

 Binder-free TiO

paste

 Compression method

 UV-O

treatment

 Anti-reflecting film

Cell efficiency reaches 8%

in their labratory.

Sol. Energy Mater. Sol. Cells 94, 812 (2010).

Plastic-based flexible DSCs

31

 Stainless steel

4.2%

Sol. Energy Mater. Sol. Cells 90, 574 (2006).

Metal-based flexible DSCs

32

 Ti foil

9.9%

Chem. Commun., 4004 (2006).

7.2%

Metal-based flexible DSCs

33

Metal based TiO

photoanode Net-like Pt counter electrodes

Sintering effects

J. Phys. Chem. C 114, 21,808 (2010)

Pt sputtering time (on net-like CE-B200) Ti foil

Metal-based flexible DSCs

34

 Ti foil: TiO

nanotubes/nanoparticles

J. Mater. Chem. 20, 7201 (2010).

Metal-based flexible DSCs

35

Research Fields of DSCs:

Electrolyte

36

Liquid electrolytes

Gel Electrolyte

Quasi-solid -state electrolytes

Ionic liquid electrolytes Electrolytes

37

Electrolytes

(1) Redox potential (2) High solubility

(3) High diffusion coefficient

(4) Absence of significant spectral characteristics in the visible region (5) High stability of both the reduced and oxidized forms of the couple (6) Highly reversible couple

(7) Chemically inert system

Electrolytes

Sol. Energy Mater. Sol. Cells 70, 85 (2001).

38

Electrolytes

Liquid electrolyte

I ^- /I ₃ ^- Co ²⁺ /Co ³⁺

Ru

N

N N

N COOH

HOOC

N N

C S C S

N719 Z907

N3

N

N N

N Ru

N C S C N S

O OH

O OH

OH O

O OH

I

+ 2e

↔ 3I

Nat., 353, 737 (1991)

Co

+ e

↔ Co

Nat. Chem., 6, 242 (2014)

39

Quasi-solid-state electrolytes

ACS Appl. Mater. Interfaces, 8, 15267 (2016)

40

Gel Electrolyte

Chem. Commun., 2972 (2002)

PVDF–HFP MPII

Z907

Adv. Mater., 23, 4199 (2011)

41

Ionic liquid electrolytes

(a) 1-hexyl-3-methylimidazolium iodide (b) 1-butyl-3-methylimidazolium iodide (c) PMII (d) EMII (e) DMII

(f) DMII/EMII (1:/1) (g) AMII

(h) DMII/EMII/AMII (1:1:1) (i) EMITCB

Electrolyte A in device A: DMII/EMII/AMII/I

/NBB/GNCS (8:8:8:1:2:0.4);

electrolyte B in device B : II/EMII/EMITCB/I

/NBB/GNCS (12:12:16:1.67:3.33:0.67)

device B

Nat. Mater., 7, 626 (2008)

42

Research Fields of DSCs:

Counter Electrode

43

Inorganic material

Pt Pt

Composite

material Carbon

Conducting polymer Counter

electrodes

44

Counter electrodes

Appl. Surf. Sci. , 253, 3242 (2007).

Chem. Commun., 2888 (2008) .

Pt counter electrodes

45

Carbon counter electrodes

Carbon Graphite

Graphene

Carbon nanotube

Active carbon Carbon black

Sol. Energy Mater. Sol. Cells, 79, 459 (2003)

J. Electrochem. Soc., 153, A2255 (2006)

Microchim Acta, 174, 73 (2011)

J. Power Sources, 239, 122 (2013) Carbon, 91, 153 (2015)

46

PEDOT PProDOT PProDOT-Et

EDOT ProDOT ProDOT-Et

J. Power Sources, 188, 313 (2009).

Conducting polymer counter electrodes

0.0 0.2 0.6 0.8

0 4 8 12 16 20

=7.77 %

=3.93 %

=7.08 %

=7.88 %

Current density

(

)

0.4 PEDOT

PProDOT PProDOT-Et

2

Pt (100 nm)

Cell voltage (V)

Counter V

(V) J

(mA/cm

) Efficiency (%) FF

Pt 0.715 17.28 7.77 0.629

PEDOT 0.705 8.84 3.93 0.630

PProDOT 0.715 16.80 7.08 0.590

PProDOT-Et

0.720 18.00 7.88 0.608

47

TiO₂ nanotubes TiO₂ nanotubes

TiN nanotubes TiN nanotubes

Chem. Commun., 6720 (2009)

Inorganic material counter electrodes

TiN MoN WN Fe

N

Energy Environ. Sci., 4, 1680 (2011)

CoSe

MoSe

Chem Commun, 50, 4475 (2014).

J. Mater. Chem. A, 2, 16023 (2014)

48

Composite material counter electrodes

TiN–NPs/PEDOT:PSS

J. Mater. Chem., 21, 19021 (2011)

CoS/PEDOT:PSS

ACS Appl. Mater. Interfaces, 3, 1838 (2011)

49

Dye-Sensitized Solar Cells in Taiwan

50

ChemPhysChem., 2014, 15, 1076

Scientific publications in dye solar cell (DSC)

51

ChemSusChem., 8, 1510 (2015)

Efficiency vs. cost prediction for G1, G2, and G3

52

Strength

Opportunity

SWOT

SWOT analysis

Weakness

Threat

 Widely and deeply researched

 Good performance at dim condition

 Low-cost manufacturing

 Portable and flexible product

 Fit to industry in Taiwan

 Less experience with application

& development

 Less focus in industry; low investment

 Cell efficiency is still low

 Poor resource

 China plagiarism counterfeiting

 Rush in Taiwan (台灣一窩蜂)

 Low barrier (產業導入門檻低)

 Application in IOT (產業轉型)

 Creativity (產學研創新)

 Need in electricity (電力供應普及)

 Competition in solar electricity

(提升太陽能發電之競爭力)

53

Acknowledgements

54

感謝中技社、科技部、中研院、工研院、臺大和福盈化學給予經費支持

Episode

55

“A product has to be developed before it’s needed;

if it’s needed, it’s too late.”

Marco Wismer

Thank you for your attention!