Singlet fission dynamics modulated by molecular configuration in covalently linked pyrene dimers, Anti- and Syn-1,2-di(pyrenyl)benzene

Abstract

Covalently linked dimers (CLDs) and their structural isomers have attracted much attention as potential materials for improving power conversion efficiencies through singlet fission (SF). Here, we designed and synthesized two covalently ortho-linked pyrene (Py) dimers, anti- and syn-1,2-di(pyrenyl)benzene (Anti-DPyB and Syn-DPyB, respectively), and investigated the effect of molecular configuration on SF dynamics using steady-state and time-resolved spectroscopies. Both Anti-DPyB and Syn-DPyB, which have different Py-stacking configurations, form excimers, which then relax to the correlated triplet pair ((T1T1)) state, indicating the occurrence of SF. Unlike previous studies where the excimer formation inhibited an SF process, the (T1T1)’s of Anti-DPyB and Syn-DPyB are formed through the excimer state. The dissociation of (T1T1)’s to 2T1 in Anti-DPyB is more favorable than in Syn-DPyB. Our results showcase that the molecular configuration of a CLD plays an important role in SF dynamics.

Intramolecular singlet fission and triplet exciton harvesting in tetracene oligomers for solar energy conversion

“…Many chromophores have been found to meet the energy requirement of SF, where the singlet state energy (E S 1 ) should be larger or equal to twice the triplet state energy (E T 1 ) (E S 1 # 2E T 1 ), such as acenes (anthracene, 19 tetracene, 20 pentacene, [21][22][23][24] hexacene [25][26][27] and their derivatives), polyene, [28][29][30][31][32][33][34] 1,3-diphenylisobenzofuran, 35 diketopyrrolopyrrole, [36][37][38][39][40] perylenediimide, [41][42][43][44][45][46] boron dipyrromethene (BODIPY), [47][48][49][50] and other chromophores. 37,[51][52][53][54][55][56][57][58][59][60][61] These molecules have been summarized in some comprehensive reviews on this eld. 7,53,[62]…”

Computational design of covalently bound dimers for singlet fission

“…Most of the effort has been dedicated to the synthesis and characterization of covalent dimers of tetracene [16][17][18][19][20][21][22][23][24] and pentacene [22,[24][25][26][27][28][29][30][31][32]. Additionally, covalent dimers of 1,3-diphenyl-isobenzofuran (DPBF) [33][34][35], aromatic diimides [36,37], perylene [38], quinoidal thiophenes [39,40], azaborine-substituted compounds [41,42], BOD-IPY [43], pyrene [44], and diphenylhexatriene [45] were designed and studied with regard to SF. Most of these investigations were focused on fine-tuning the throughbond coupling between chromophores by testing different combinations of linkers and connecting sites [16-18, 22, 23, 25-30, 33, 35, 41, 42, 45], while fewer studies were dedicated to the optimization of the through-space interaction [19,20,24,[36][37][38].…”