BODIPY COMPOUNDS AS NONINNOCENT SPACERS FOR DSSC DYES

BODIPY COMPOUNDS AS NON-INNOCENT πSPACERS FOR DSSC DYES Devin D. Machin, Catherine Bonnier, Bryan D. Koivisto* Science at the Interface August 14, 2012 Department of Chemistry and Biology Ryerson University

2 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. Solar energy has promising 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 Ti. O 2 • 3. The e- enters the circuit • 4. The dye molecule is reduced by the electrolyte

4 The Dye Molecule • The dye molecule is the powerhouse of the DSSC Sun, L. et al. , J. Org. Chem. , 2007, 9550. • Organic dyes typically follow a Donor-π-spacer-Acceptor motif • The use of BODIPY and a non- innocent π-spacer for DSSC dyes is explored

5 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. Conjugation is interrupted by the orientation of the Indicated phenyl group Mau, M. et al. , Dyes Pigments. , 2012, 231. Indicated group is a poor electron donor Erten-Ela, S. et al. , Org. Lett. , 2008, 3300.

6 Target molecules • A family of BODIPY dyes with modified conjugation lengths for red-shifted absorption

7 Synthesis of Target 2 a & 2 b 2 b in DCM • Fluorescence of BODIPY is quenched through the addition of donor and anchor groups

8 Synthesis of Target 5 a & 5 b 5 b in DCM

9 Cyclic Voltammetry and DFT HOMO LUMO B 3 LYP/6 -31 G Calibrated vs Ferrocene (not shown)

e 104 (M-1 cm-1) 10 UV-vis Spectra Comparison 9 8 BODIPY 7 2 b 6 5 b 5 4 Hagfelt, A. et al. , Chem Rev. , 2010, 6595. 3 • Dyes 2 b and 5 b 2 1 0 230 330 430 530 l /nm 630 730 show red shifted absorptions tailing off to 630 nm

11 Summary and Future work • 6 of 8 target molecules were successfully synthesized. • These dye molecules have promising physical properties (UV-vis, CV) • Dyes will be used in prototype devices to determine conversion efficiency • Future synthesis utilizing other organic frameworks as noninnocent π-spacers

12 Acknowledgements People Current Group Dr. Bryan Koivisto (PI) Dr. Catherine Bonnier (PDF) Devin Machin (BSc) Omar Abdi (BSc) Muhammad Yousaf (MSc) Funding Left to Right: Devin, Catherine, Bryan, Muhammad, & Omar