Multiexcitonic Triplet Pair Generation in Oligoacene Dendrimers as Amorphous Solid‐State Miniatures

Abstract

Singlet fission in organic semiconducting materials has attracted great attention for the potential application in photovoltaic devices. Research interests have been concentrated on identifying working mechanisms of coherent SF processes in crystalline solids as ultrafast SF is hailed for efficient multiexciton generation. However, as long lifetime of multiexcitonic triplet pair in amorphous solids facilitates the decorrelation process for triplet exciton extractions, a precise examination of incoherent SF processes is demanded in delicate model systems to represent heterogeneous structures. Heterogeneous coupling and energetics for SF were developed in our oligoacene dendrimers, which mimic complicated SF dynamics in amorphous solids. SF dynamics in dendritic structures was thoroughly investigated by time‐resolved spectroscopic techniques and quantum chemical calculations in respect of the relative orientation/distance between chromophores and though‐bond/‐space interactions.

Exploring a new class of singlet fission fluorene derivatives with high-energy triplets

“…7,8 Although this phenomenon has become a hot topic in chemical research, the families of SF capable materials remain relatively limited 9 and several mechanistic details of the SF process remain unclear. [10][11][12] Notably, the inuence of intramolecular charge transfer (ICT) on the SF has been the object of recent investigations carried out on dimers of tetracene, 13 pentacene, [14][15][16][17][18] terrylenediimide, [19][20][21][22][23] diketopyrrolopyrrole, [24][25][26][27][28] on tetracene and perylenediimide oligomers or dendrimers [29][30][31] and on push-pull polymers. [32][33][34] These studies generally consider either the effect of solvent polarity or the effect of tuning the electron donor/ acceptor group strength on the SF.…”

Synergetic Role of Conformational Flexibility and Electronic Coupling for Quantitative Intramolecular Singlet Fission

“…The mechanism for the generation of TT is well-studied in both intermolecular (xSF) (e.g., solid-state) and intramolecular SF (ISF) (covalently linked dimers). − In both cases, a strong electronic coupling between two chromophores accelerates the rate constants of TT generation and the corresponding reverse reaction: triplet–triplet annihilation (TTA). , In xSF, ultrafast SF within a few picosecond time scale was observed because of strong electronic coupling with coherent SF from S 1 to a vibronically excited 1 (TT) and direct SF from the upper excited singlet state (S n ) to 1 (TT). ,− These features are also highly related with the hybridization of wave functions of S 1 , T 1 , and the charge-transfer (CT) excited states …”

Theoretical Engineering of Singlet Fission Kinetics in Perylene Bisimide Dimer with Chromophore Rotation

“…The recent benchmark study on electronic excitation energy and exciton’s behavior show that the long-range-corrected (LRC) density functionals perform well . Among a various type of LRC functionals, we selected the CAM-B3LYP-D functional on the basis of the previous successful application to investigate the SF process in covalently linked PBI dimers and acene dendrimeric structures, , and similar excitation energy compared to ωB97X-D, which is the widely employed functional to compute SF-relevant electronic structures. The binding energy is defined as the energy difference between a dimer and two monomers; therefore, negative signs indicate a favorable interaction.…”