Singlet Fission in 9,10-Bis(phenylethynyl)anthracene Thin Films

Abstract

Singlet fission (SF) in two or more electronically coupled organic chromophores converts a high-energy singlet exciton into two low-energy triplet excitons, which can be used to increase solar cell efficiency. Many known SF chromophores are unsuitable for device applications due to chemical instability and low triplet state energies. The results described here show that efficient SF occurs in polycrystalline thin films of 9,10bis(phenylethynyl)anthracene (BPEA), a commercial dye that has singlet and triplet energies of 2.40 and 1.11 eV, respectively, in the solid state. BPEA crystallizes into two polymorphs with space groups C2/c and Pbcn, which undergo SF with kSFA = (109 ± 4 ps) −1 and kSFB = (490 ± 10 ps) −1 , respectively. The high triplet energy and efficient SF evidenced from the 180 ± 20% triplet yield make BPEA a promising candidate for enhancing solar cell performance.

Controlling the structure and photophysics of fluorophore dimers using multiple cucurbit[8]uril clampings

“…[37][38][39] A complete study was carried out on Ant910Me, which contains a 9,10-anthracenyl ("Ant910") as the central core and p- Modular strategy for designing fluorescent molecules (a) by plugging in a fluorophore module between two positively charged clamping modules, which herein are arylpyridinium moieties originated from diarylviologen derivatives. Following this strategy, (b) 2,7naphthalene with non-parallel clamping modules, as an example, or (c) other fluorophores with various arrangement of clamping modules are expected to form a preorganized dimer constrained by CB[8]-mediated multiple clamping or a monomeric state of fluorophores protected by CB [7] from aggregation. The Cl À counterions are omitted for clarity.…”

“…Guest molecule (G) Ant910Me is found to form 1 : 2 complexes with CB [7], denoted G 1 -CB[7] 2 , and 2 : 2 complexes with CB [8], denoted G 2 -CB[8] 2 . The complex formations are veried by several NMR techniques including 1 H NMR, 2D nuclear Overhauser spectroscopy (NOESY), and diffusion ordered spectroscopy (DOSY).…”

“…Coupling two uorophores within a sufficiently short distance for an extended period of time is crucial for both theoretical and experimental investigation of intermolecular processes such as charge transfer, 1 excimer formation, 2,3 long-or short-range exciton coupling, 4,5 and singlet ssion. [6][7][8] Stacking together precisely two uorophores in an aqueous solution, however, remains a substantial challenge as most aromatic hydrocarbons show a tendency to aggregate unpredictably (forming clusters of arbitrary numbers of molecules). [9][10][11] To prevent uorophores from aggregation in aqueous solution, a supramolecular approach has been established to "mechanically" separate uorescent molecules through encapsulation by macrocycles.…”

“…[12][13][14][15][16] A popular class of macrocyclic hosts utilized for this purpose is cucurbit[n]uril (CB[n], n ¼ 5-8, 10), which contains a cavity that enables the inclusion of various guest molecules and exhibits particularly high affinity towards positivelycharged species. 17,18 As an example, CB [7] is a promising host for the complexation of various uorescent dyes, 19 resulting in signicant changes in photophysical properties such as antiphotobleaching 20 and emission enhancement. [21][22][23] This is attributed to the hydrophobic environment provided by the CB cavity as well as mechanical protection by the macrocycle against aggregation and quenching.…”

“…[21][22][23] This is attributed to the hydrophobic environment provided by the CB cavity as well as mechanical protection by the macrocycle against aggregation and quenching. 12 Dimeric uorophore stacking, however, is unlikely to be realized by CB [7]-mediated complexation as its relatively small cavity only allows the complexation with one single guest molecule or, more strictly speaking, one binding moiety on a guest molecule. On the other hand, CB [8], a larger cucurbituril homologue, is capable of simultaneously encapsulating two guest moieties yielding either a heteroternary 24 or homoternary complex.…”