Ultrafast Dynamics and Estimation of Singlet Exciton Diffusion Parameters for Nanoaggregates of peri and bay Anisyl Perylene

Abstract

The correlation between molecular structure and its photophysics is well reported, and organic chemistry is blessed with the freedom of substitution to obtain the desired photophysical property, suitable to control the functional aspects of materials. Despite the fact that the photodynamics of perylene has been studied in depth, its bay and peri aryl-substituted derivatives have not been studied to that extent. Herein, the ultrafast photodynamics of two anisyl perylene derivatives (peri-OCH 3 and bay-OCH 3 ) is presented. Isomers of anisyl perylene were designed to study the positional effect of substitution on their molecular packing and excited-state photophysics. The fluorescence spectra of nanoaggregates of peri-OCH 3 showed excimer formation, while monomer emission is dominated in bay-OCH 3 . These features are consistent with the solid-state α-phase and β-phase of perylene, respectively, which are grown in a very precise and controlled manner. Excited-state dynamics studies show that in peri-OCH 3 , the monomeric free excitons undergo a relatively faster decay to populate the self-trapped monomeric excitonic state and E-state. In bay-OCH 3 , the contribution of emission from the Y-state and E-state is much less. The molecular structure alteration and different packing are also observed to have an impact on the exciton diffusion rate. The bay-OCH 3 isomer is observed to have an almostdouble diffusion length, which is attributed to the slightly faster diffusion and longer lifetime of free excitons. The present report indicates the structural modulation effect on the exciton-to-excimer transition dynamics and exciton diffusion properties, which can be beneficial in designing perylene-based materials for organic electronics.

Synergistic effects of side-functionalization and aza-substitution on the charge transport and optical properties of perylene-based organic materials: a DFT study

“…, in the short-wavelength region (230–275 nm) and long-wavelength region (440–500 nm), which are consistent with several peri-substituted perylenes reported in the literature. 1,37,68 Among other compounds in this series, the presence of electron donating thiophene rings in P3 and P4 significantly red-shifted the absorption spectra. The absorption maxima of these compounds in the long-wavelength region are attributed to the S 0 → S 1 transition, which are predominantly composed of the HOMO → LUMO (>98%) orbital contribution.…”

“…The polycyclic conjugated frameworks of organic semiconductors (OSCs) are being intensely useful in tuning the efficacy of organic-based flexible electronic devices, including light emitting diodes (LEDs), solar cells (SCs), thin film-field effect transistors (TF-FETs), electrochemical transistors (ECTs), sensors and so on. [1][2][3][4][5] The device efficiency is primarily determined by the ease of hole/electron transport in the material, which can be manipulated by suitable molecular modelling, crystal packing, and the p-orbital overlapping between the neighbouring molecules in the crystal. Among various small-molecule OSCs, compounds such as anthracene, pentacene, pyrene, perylene, coronene, rubrene, etc.…”

Phase modulated scanning near field optical luminescence imaging as a probe of exciton dark lifetime and diffusivity in persistently luminescent micro- and nanocrystals

“…Table 1 assesses the resolution, both spatial (lateral) and in the time domain of different techniques normally used to determine the exciton diffusion length in optical materials and nanomaterials. A significant advantage of PM-SNOL is that it possesses both significant lateral and time-domain resolution differently from state-of-the-art ultrafast [51][52][53][54][55][56][57][58][59] (Table 1, first row) imaging [60][61][62][63][64][65] (second row) techniques for exciton diffusion length measurements, which only possess either of them. As far as ultimate lateral resolution is concerned, PM-SNOL measurements are only limited by the ultimate resolution of the scanning-near field optical microscope used to perform them, which in our case is of the order of the tip aperture, 28,66 and therefore of the order of hundreds of nanometers.…”

Efficient Singlet Fission in Perylenediimide Derivative Nanocrystals

“…Studies on rigid perylene bisimide aggregates indicate the creation of excimer and delocalized radical anion state, and subtle changes in the molecular structure lead to different photophysical material properties . In recent years, there have been numerous studies related to PDI and PDI derivatives. − Some researchers believe that PDI films have the potential to perform similarly to high-cost single crystals in SF based photovoltaic applications . However, most studies on the SF process of PDI and PDI derivatives are confined to solutions and amorphous or polycrystalline films.…”