Effect of number of anchoring groups on binding ability of perylene diimides with SnO2 and TiO2 nanoparticles: A spectroscopic approach

The consequence of number of anchoring groups on the binding ability of amino acid substituted perylene diimides with SnO2 and TiO2 semiconductor nanoparticles were investigated by various spectroscopic techniques for photovoltaic applications. For this purpose, two symmetrical and one new unsymmetrical perylene diimides were synthesized and characterized by IR, NMR and Mass spectroscopy. Optical properties of all the three compounds were investigated. Ground state interactions between the perylene diimides and semiconductor nanoparticles were probed through absorption measurements. The binding constant data were calculated from the fluorescence measurements. The results revealed that the sensitizer having two anchoring groups in close proximity possess lesser binding constant with semiconductor nanoparticles. Electron transfer mechanism was proposed and confirmed through Rehm Weller equation. The present work will pave the way for future designing of sensitizers with anchoring groups.