Theoretical study of intramolecular singlet fission in xanthene-bonded pentacene dimers

Abstract

Singlet fission is a spin-allowed process by which two non-interacting triplet excitons are generated from a singlet exciton. This type of multiexciton generation mechanism may have the potential to overcome the Shockley-Queisser limit and could enable the development of more efficient solar cells. In this contribution, we analyze intramolecular singlet fission in two modified pentacene dimers covalently bonded to a xanthene spacer employing density functional theory and multireference perturbation theory methods. The systems investigated differ in the electronic structure and bulkiness of the substituents used and in this work we analyze the impact that these aspects have in the relative contributions of the direct and mediated mechanisms to the intramolecular singlet fission.

Davydov splitting and singlet fission in excitonically coupled pentacene dimers

“…¶Xanthene linked tetracenes have been reported 19,67 20,68 Using these pentacene dimers in dilute solution, we outline the role of inter-chromophore coupling through direct π-overlap, which leads to solid-state-like Davydov splitting. Transient absorption spectroscopy enables us to define the influence of Davydov splitting on the excited-state processes.…”

Re‐Thinking Dimer Design Principles with Indolonaphthyridine Intramolecular Singlet Fission

“…The vast majority of studies on dimeric systems have been performed on acene based dimers [18–27] . In particular pentacene dimers have been extensively studied and the rate of singlet fission has been shown to be highly dependent on the nature of the linker [6,19,31–37,23–26,28,29,29,30] . However, in terms of practicality, acenes are of limited use due to their photoinstability and inappropriate triplet energy level [38,39] .…”

“…[18][19][20][21][22][23][24][25][26][27] In particular pentacene dimers have been extensively studied and the rate of singlet fission has been shown to be highly dependent on the nature of the linker. [6,19,[31][32][33][34][35][36][37][23][24][25][26]28,29,29,30] However, in terms of practicality, acenes are of limited use due to their photoinstability and inappropriate triplet energy level. [38,39] Therefore it is important to assess whether the design rules that have been found for acene dimers are applicable to other materials which have the potential for greater stability and/or more tunable triplet energy levels.…”

Quantum dynamical simulation of intramolecular singlet fission in covalently coupled pentacene dimers

“…1,[12][13][14][15] Subsequent evolution controlled by the magnetic dipole-dipole interaction leads to the formation of separate, triplet excitons in a process where several states of different spin multiplicity interact in a complex interplay. 1,[16][17][18][19][20][21][22][23][24][25] The complexity of the process has motivated an important theoretical research effort to decipher SF, which implies identifying the electronic states participating in the process, their roles [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] and coupling mechanisms 1,[42][43][44][45][46][47][48][49][50][51] and characterizing the dynamics, including the role of mode specific aspects of the nuclear motion, conical intersections, interference and decoherence effects. ...…”