Assessing the Potential of Peropyrene as a Singlet Fission Material: Photophysical Properties in Solution and the Solid State

Abstract

The photophysical behavior of the polycyclic aromatic hydrocarbon peropyrene is studied both in dilute solution and in the solid state, with the goal of evaluating this molecule as a singlet fission (SF) material. In solution, the fluorescence quantum yield is consistently in the range 0.90−0.95, while the fluorescence lifetime changes from 3.2 to 5.5 ns. Analysis of the solvent dependence of the radiative rate provides evidence that the bright 1 B u singlet state mixes with a second, optically dark state. The presence of a dark state slightly above the 1 B u state in energy is confirmed using two-photon fluorescence excitation spectroscopy. The crystal structure of solid peropyrene consists of a herringbone arrangement of π-stacked molecular pairs, similar to the αpolymorph of perylene. There are two emitting species, centered at approximately 550 and 650 nm, both of which are formed within the 15 ps time resolution of the experiment, and which relax independently via biexponential decays. We find no evidence for rapid SF in the peropyrene crystals, most likely due to the large shift of the singlet state to lower energy where it no longer fulfills the energy condition for SF. These results demonstrate how both energetics and crystal packing influence the ability of a molecule to function as a SF material.

Excited-State Dynamics of Diindenoperylene in Liquid Solution and in Solid Films

“…34 The increased conjugation leads to a red shift of about 100 nm relative to those molecules, with the lowest energy peak located at 540 nm. A more profound difference is that DIP's fluorescence spectrum does not mirror its absorption but is broadened with a different vibronic intensity pattern.…”

Soluble and Planar 2,9‐Diazaperopyrenes through Reductive Aromatization of Perylene Diimides: Tunable Emission and Aggregation Behaviors

“…Along this line, peropyrene is a fascinating molecule containing both pyrene and perylene subunits. Because of its large π‐conjugated system and planar core structure, peropyrene is expected to show photoconductivity and singlet fission phenomena (Figure ) …”

Pyrenes, Peropyrenes, and Teropyrenes: Synthesis, Structures, and Photophysical Properties

“…[6] However,agood method to introduce substituents onto peropyrene to improve its physical properties is still lacking.A st he next longer analogue,t eropyrene is expected to exhibit ab athochromic shift in both absorption and emission bands with respect to both pyrene and peropyrene,a sw ell as al ower band gap owing to its extended p system. [6] However,agood method to introduce substituents onto peropyrene to improve its physical properties is still lacking.A st he next longer analogue,t eropyrene is expected to exhibit ab athochromic shift in both absorption and emission bands with respect to both pyrene and peropyrene,a sw ell as al ower band gap owing to its extended p system.…”

“…Fore xample,B ardeen and co-workers assessed its potential use as as inglet fission material, thus pointing out that including substituents on peropyrene should improve peropyrenes singlet fission properties. [6] However,agood method to introduce substituents onto peropyrene to improve its physical properties is still lacking.A st he next longer analogue,t eropyrene is expected to exhibit ab athochromic shift in both absorption and emission bands with respect to both pyrene and peropyrene,a sw ell as al ower band gap owing to its extended p system. In 1975, Misumi and coworkers reported the first teropyrene synthesis from multilayered metacyclophanes by at ransannular reaction/dehydrogenation sequence,a nd it was characterized only by its absorption spectrum because of poor solubility.…”