Tunable Photophysics of Self-Assembled Phe-Phe Dipeptide Doped with Luminescent Compounds

T. Martins, G. Sousa, D. Cordeiro, R. Miranda
Federal University of Goias,
Brazil

Keywords: FLIM, fluorescence, peptide self-assembled nanostructures, energy conversion

Summary:

Self-assembled peptide nanostructures are easily prepared through supramolecular approaches that enable the control of the final structures. In particular, peptides containing at least one diphenylalanine unit have presented electro-optical properties that can be exploited in several electron transfer processes, such as energy conversion, in electro-optical devices, and sensing. Due to their chemical stability, biocompatibility good morphological characteristics, the ease of preparation in liquid medium and because, they have been combined to electroluminescent materials to present new and unique photophysical and morphological properties. When combined to thin films of organic polymers and molecules, they influence the energy transfer processes that occur in such systems, which alter their photophysical responses and can be used in energy generation through photovoltaic effect, when applied as active layers of solar cells, for instance. In this work, nanotubes and nanovesicles of diphenylalanine were combined to thin films of poly(2-metoxy-5-(2ยด-ethylhelyloxy)-p-phenylene-vinylene) - (MEH-PPV), polyvinylcarbazole (PVK) and LBL films of rubrene, 9-vinyl-carbazole and coumarin-6 to generate new materials that were deposited on lead-free perovskite thin films. The photophysical properties of such combinations are determined by steady-state fluorescence spectroscopy, time-resolved fluorescence spectroscopy and by fluorescence lifetime imaging microscopy (FLIM) and their morphological characteristics were determined by scanning electronic microscopy and fluorescence microscopy. These techniques give information to enable the understanding of the conformational orientation and specific interactions between the self-assembled structure and the electroluminescent compounds, which are indispensable to ensure the right application of such materials.