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

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

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

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.

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, 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

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

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

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

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

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

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