(Invited) Beta, Beta-Functionalized Push-Pull Opp-Dibenzoporphyrins As Sensitizers for Dye-Sensitized Solar Cells: The Role of the Phenylethynyl Bridge and the Tertiary Amine Push Group

Abstract

Significant progress has been made on dye-sensitized solar cells sensitized by push-pull porphyrins in recent years.1-3 An effective way to significantly enhance power conversion efficiencies of porphyrin dyes is through installation of push (electron-donating) and pull (electron-withdrawing) groups at porphyrin meso-positions.4-6 In this presentation, we present a different strategy to install push and pull groups at porphyrin beta-positions. Three series of novel opp-dibenzoporphyrins were prepared using this strategy. Our studies show significant push-pull effects for these porphyrins.7 DFT calculations suggest that the inclusion of ethynylphenyl bridge between the donating group and porphyrin core significantly segregate the frontier orbitals, which is a much-favored feature for sensitizers in DSSC. The electronic and optical properties of these beta-extended porphyrins were measured using UV-Vis spectroscopy, life-time and steady state fluorescence spectroscopy, cyclic voltammetry and transient spectroscopy. Their photovoltaic performances were tested in dye-sensitized solar cells. Reference T. Higashino and H. Imahori, Dalton Trans., 2015, 44, 448-463.M. Urbani, M. Gratzel, M. K. Nazeeruddin and T. Torres, Chem. Rev., 2014, 114, 12330-12396.L. L. Li and E. W. Diau, Chem. Soc. Rev., 2013, 42, 291-304.A. Yella, H.-W. Lee, H. N. Tsao, C. Yi, A. K. Chandiran, M. K. Nazeeruddin, E. W.-G. Diau, C.-Y. Yeh, S. M. Zakeeruddin and M. Grätzel, Science, 2011, 334, 629-634.S. Mathew, A. Yella, P. Gao, R. Humphry-Baker, B. F. Curchod, N. Ashari-Astani, I. Tavernelli, U. Rothlisberger, M. K. Nazeeruddin and M. Gratzel, Nat. Chem., 2014, 6, 242-247.G. Di Carlo, A. O. Biroli, F. Tessore, S. Caramori and M. Pizzotti, Coord. Chem. Rev., 2018, 358, 153-177.Y. Hu, S. Yellappa, M. B. Thomas, R. G. W. Jinadasa, A. Matus, M. Shulman, F. D'Souza and H. Wang, Chem Asian J, 2017, 12, 2749-2762.