1. BODIPY COMPOUNDS AS NON-INNOCENT π- SPACERS 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. 2 Solar energy has promising potential

3. The Dye Sensitized Solar Cell (DSSC) 3 The DSSC is a promising next generation PV technology 1. A photon is absorbed 2. The excited e - is injected into TiO 2 3. The e - enters the circuit 4. The dye molecule is reduced by the electrolyte

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

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. 5 Erten-Ela, S. et al., Org. Lett., 2008, 3300. Mau, M. et al., Dyes Pigments., 2012, 231. Conjugation is interrupted by the orientation of the Indicated 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 6

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

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

9. Cyclic Voltammetry and DFT 9 HOMO LUMO B3LYP/6-31G Calibrated vs Ferrocene (not shown)

10. UV-vis Spectra Comparison 10 Hagfelt, A. et al., Chem Rev., 2010, 6595. Dyes 2b and 5b 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) 11 Dyes will be used in prototype devices to determine conversion efficiency Future synthesis utilizing other organic frameworks as non- innocent π-spacers

12. Acknowledgements Current Group Dr. 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