First-principles study of bioinspired perylene diimide molecular nanowires*

Perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) has excellent electrochemical and photophysical properties that makes it a promising material for optoelectronic devices. Molecular nanowires consisted from PTCDI derivatives can be placed in DNA like base by standard automated oligonucleotide synthesis. Here, we study the electronic and optical properties of a series of recently synthesized bioinspired perylene diimide molecular nanowires by first-principles density functional theory (DFT) spectroscopy and molecular dynamics (MD). We apply time-dependent DFT with Franck-Condon analysis to study our material. Initial structures are taken from MD and the final vibronic spectra is an average over many structures. By stacking the molecules along a DNA-like backbone and varying the number of stacked molecules from one to four, we determine the role of inter-molecular interactions on the excited-state energetics, as well as vibrational excitations within the molecules. We demonstrate that strong inter-molecular interactions lead to distinct vibrational, electronic, and optical properties for design of new electronic and optoelectronic nanowires.