Optical absorption signature of a self-assembled dye monolayer on graphene

Abstract

SummaryA well-organized monolayer of alkylated perylene-3,4,9,10-tetracarboxylic-3,4,9,10-diimide (PTCDI) has been formed onto CVD graphene transferred on a transparent substrate. Its structure has been probed by scanning tunnelling microscopy and its optical properties by polarized transmission spectroscopy at varying incidence. The results show that the transition dipoles of adsorbed PTCDI are all oriented parallel to the substrate. The maximum absorption is consistent with the measured surface density of molecules and their absorption cross section. The spectrum presents mainly a large red-shift of the absorption line compared with the free molecules dispersed in solution, whereas the relative strengths of the vibronic structures are preserved. These changes are attributed to non-resonant interactions with the graphene layer and the neighbouring molecules.

Substrate-induced shifts and screening in the fluorescence spectra of supramolecular adsorbed organic monolayers

“…These values are very close to the measured absorption peak for alkylated PTCDI derivatives adsorbed on graphene 33 .…”

A Computational Predictive Approach for Controlling the Morphology of Functional Molecular Aggregates on Substrates

“…Interestingly, the surface area of the unit cell for the IL phase (about 1.5 nm 2 ) is smaller than the projected surface area of a single PTCDI‐C13 molecule (about 2.5 nm 2 ), as also evidenced in experiments . As shown in Figure , this tight packing is realized by a partial overlap of the PTCDI‐C13 alkyl chains onto the core of neighboring molecules, as it was postulated in previous work . It is also worth noting that an isolated cluster with the same number (68) of PTCDI‐C13 molecules in the 2D CF (standing on) configuration on the 10 × 10 nm surface is unstable under MD at room temperature and relaxes to a disordered lay‐on configuration.…”

“…The role of molecular structure and morphology at the nanoscale is particularly relevant in the formation of aggregates at the interface with a substrate, where the interplay between the emerging polymorphism of perylene diimide derivatives and the effect of processing has strong consequences on charge transport properties in devices. In particular, PTCDI‐C13 constitutes a suitable benchmark to assess the predictive power of our approach, as it is known to form different aggregated structures at the nanoscale depending on fabrication conditions and on the nature of the underlying substrate . Graphene, on the other hand, besides being a material of paramount technological relevance, can also be considered as an ideal 2D substrate for the formation of heterojunctions with molecular systems .…”

Poly[(arylene ethynylene)-alt-(arylene vinylene)]s Based on Anthanthrone and Its Derivatives: Synthesis and Photophysical, Electrochemical, Electroluminescent, and Photovoltaic Properties

“…The absorption spectra of the P2 and P3 copolymers with anthanthrene unit significantly differ from the spectra of P1 . The corresponding SM model compound for P2 and P3 exhibits well resolved absorption spectrum in toluene and DCB solutions that are typical of fused conjugated systems, 51 − 54 with maxima at 327, 400, 447, and 477 nm in toluene and slightly red-shifted maxima at 332, 405, 450, and 480 nm in DCB. The absorption spectrum of SM thin film is not so well resolved reflecting the intermolecular interactions in solid state.…”