BODIPY COMPOUNDS AS NON-INNOCENT π-SPACERS FOR DSSC

DYESDevin D. Machin, Catherine Bonnier, Bryan D. Koivisto*

Science at the Interface August 14, 2012

Department of Chemistry and BiologyRyerson University

The Opportunities For Solar Technology

• Crystalline silicon photovoltaics (PV’s) dominate the solar technology market

• They are a mature technology, efficient and robust

• However, they are expensive and have limited design potential.

2

Solar energy haspromising potential

3

The Dye Sensitized Solar Cell (DSSC)

The DSSC is a promising next generation PV technology

• 1. A photon is absorbed• 2. The excited e- is injected

into TiO2

• 3. The e- enters the circuit• 4. The dye molecule is

reduced by the electrolyte

4

The Dye Molecule

N

S

O

OH

CN

n = 2.75%

• The dye molecule is the powerhouse of the DSSC

• The use of BODIPY and a non-innocent π-spacer for DSSC dyes is explored

AD spacer

NB

N

F F

AD

BODIPY

• Organic dyes typically follow a Donor-π-spacer-Acceptor motifSun, L. et al., J. Org. Chem., 2007, 9550.

5

NB

N

F F

N N

NC

OHO

n = 1.66%

Boron-Dipyrromethene (BODIPY)

• A robust moiety, that is redox stable and therefore can be used to increase the absorption envelope and long-term stability of DSSC dyes.

NB

N

F F

Erten-Ela, S. et al., Org. Lett., 2008, 3300.

Mau, M. et al., Dyes Pigments., 2012, 231.

O

O

N

HN

NB

N

F F

NC O

OH

n = 2.26%

Conjugation is interrupted by the orientation of theIndicated phenyl group

Indicated group is a poor electron donor

6

Target molecules• A family of BODIPY dyes with modified conjugation

lengths for red-shifted absorption

NB

N

F F

N

OR

CNHO

O

OR2a R = Me2b R = Hex

NB

N

F FCNHO

O

N

RO

ORS

3a R = Me3b R = Hex

NB

N

F F

N

OR

OR

NC

HO

O

S

4a R = Me4b R = Hex

NB

N

F F

N

RO

ORSNC

OH

O S

5a R = Me5b R = Hex

7

Synthesis of Target 2a & 2b

NB

N

F F

N

OR

OR

CNO

HO

NCO

OH

CHCl3reflux 36h

2a R = Me2b R = Hex

NB

N

F F 1

NB

N

F F

I

6

NBO

O

OR

OR

Pd(PPh3)4K2CO3

THF:H2O 9:1reflux 12 h

NB

N

F F

N

OR

OR

NB

N

F F

N

OR

OR

ODMFPOCl3

1,2-dichloroethane,rt, 3 h

7a R = Me7b R = Hex

8a R = Me8b R = Hex

DCMrt, 12 h

NIS

piperdine

NI

OO

= NIS

2b in DCM• Fluorescence of BODIPY

is quenched through the addition of donor and anchor groups

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NB

N

F F

NB

N

F F

IIN

BN

F F

S

S

NB

N

F F

S

SI

SB

O

O

Pd(PPh3)4K2CO3

THF:H2O 9:1reflux 12 h

1 9 10

11

DCMrt, 12 h

NIS

DCMrt, 12h

NIS

BO

O

Pd(PPh3)4K2CO3

THF:H2O 9:1reflux 12 h

NB

N

F FS

S

DMFPOCl3

1,2-dichloroethane,rt, 3 h

NB

N

F FS

S

O

NB

N

F F

S

NCO

OH

CHCl3reflux 36 h

5a R = Me5b R = Hex

SCN

O

OH

12a R = Me12b R = Hex

13a R = Me13b R = Hex

R

N

OR

OR D

DD

D =

piperdine

Synthesis of Target 5a & 5b

5b in DCM

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Cyclic Voltammetry and DFT

HOMO

LUMO

NB

N

F F

N

OMe

OMe

CNO

HO

B3LYP/6-31G Calibrated vs Ferrocene (not shown)

10

230 330 430 530 630 7300

1

2

3

4

5

6

7

8

9

BODIPY

2b

5b

l /nm

e 1

04 (M-1cm

-1)

UV-vis Spectra Comparison

Hagfelt, A. et al., Chem Rev., 2010, 6595.

• Dyes 2b and 5b show red shifted absorptions tailing off to 630 nm

Summary and Future work • 6 of 8 target molecules were

successfully synthesized.• These dye molecules have promising

physical properties (UV-vis, CV)

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• Dyes will be used in prototype devices to determine conversion efficiency

• Future synthesis utilizing other organic frameworks as non-innocent π-spacers

NB

N

F F14

NB

N

C8H17

C8H17 C8H76

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Acknowledgements

Current GroupDr. Bryan Koivisto (PI)Dr. Catherine Bonnier (PDF)Devin Machin (BSc)Omar Abdi (BSc)Muhammad Yousaf (MSc)

Left to Right: Devin, Catherine, Bryan, Muhammad, & Omar

People

Funding

12