Mutually exclusive hole and electron transfer coupling in cross stacked acenes

Benny, Alfy; Hariharan, Mahesh

doi:10.1039/d1sc00520k

Cited by 22 publications

(26 citation statements)

References 51 publications

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“…Our continuous efforts to understand the excited-state dynamics of orthogonal/near-orthogonal arranged multichromophoric architectures motivated us to dwell in the realm of excited-state structural rearrangement and the associated deactivation pathways. 32,44,49–53 Herein, we showcase the transformation of an initially populated SB-CS state to a detrimental excimer state due to excited-state conformational changes. Near-orthogonal stacked SC-SPDI 2 and SC-NPDI 2 undergo ultrafast structural relaxation to a foldamer structure, leading to a direct population of the excimer state in toluene.…”

Section: Introductionmentioning

confidence: 98%

Excimer evolution hampers symmetry-broken charge-separated states

2022

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Section: Introductionmentioning

confidence: 98%

Excimer evolution hampers symmetry-broken charge-separated states

2022

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“…Yet another example of null exciton splitting was realized in a series of pentacene derivatives existing in orthogonal molecular stacks . The orthogonally cross-stacked linear and nonlinear acene dimers were found to exhibit mutually exclusive hole and electron transfer coupling …”

Section: Introductionmentioning

confidence: 99%

“…52 The orthogonally cross-stacked linear and nonlinear acene dimers were found to exhibit mutually exclusive hole and electron transfer coupling. 53 Though vital for optoelectronic application, a comprehensive understanding of the excited-state dynamics of very weak/ null excitonic coupled chromophores remains rare. Recently, Kim, Wurthner, and co-workers reported efficient multiexciton state generation in a null exciton-coupled perylenediimide foldamer by the large charge-transfer coupling between the chromophores.…”

Section: ■ Introductionmentioning

confidence: 99%

Null Exciton-Coupled Chromophoric Dimer Exhibits Symmetry-Breaking Charge Separation

2021

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A comprehensive understanding of the structure− property relationships in multichromophoric architectures has pushed the limits for developing robust photosynthetic mimics and molecular photovoltaics. The elusive phenomenon of null exciton splitting has gathered immense attention in recent years owing to the occurrence in unique chromophoric architectures and consequent emergent properties. Herein, we unveil the hitherto unobserved null exciton coupling assisted highly efficient photoinduced symmetry-breaking charge separation (SB-CS) in a Greek cross (+)-oriented spiro-conjugated perylenediimide dimer (Sp-PDI 2 ). Quantum chemical calculations have rationalized the infrequent manifestation of null exciton coupling behavior in Sp-PDI 2 . Negligible contribution of long-range Coulombic and shortrange charge-transfer mediated coupling renders a monomer-like spectroscopic signature for Sp-PDI 2 in toluene. The Greek cross (+)-arranged Sp-PDI 2 possesses a selective hole-transfer coupling, facilitating the ultrafast dissociation of null excitons and evolution of the charge-separated state in polar solvents. Radical cationic and anionic spectroscopic signatures were characterized by employing femtosecond transient absorption spectroscopy. The substantial hole transfer electronic coupling and lower activation energy barrier of Sp-PDI 2 accelerated the charge separation rate. The rate of charge recombination (CR) markedly decelerated due to falling into the inverted region of the Marcus parabola, where the driving force of CR is larger than the total reorganization energy for CR. Hence, the ratio of the rates for SB-CS over CR of Sp-PDI 2 exhibited an unprecedently high value of 2647 in acetonitrile. The current study provides impeccable evidence for the role of selective charge filtering in governing efficient SB-CS and thereby novel insights towards the design of biomimics and advanced functional materials.

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“…42 In this context and in line with our sustained efforts for identifying distinct crystalline chromophoric architectures exhibiting interesting optoelectronic properties, we investigate the role of interplanar rotation of chromophores towards effective SF. [43][44][45][46] While extensive theoretical investigations in the past have helped construct a holistic picture of the merits and demerits of slip-stacking, 14,15,27,34 reports of SF varying with respect to rotational offsets remain limited. Wasielewski and co-workers predicted advantageous interchromophoric electronic coupling in rotational offsets to be responsible for the enhanced triplet yield observed in a twisted (rotated) TDI derivative compared to the untwisted, slip-stacked derivative.…”

Section: Introductionmentioning

confidence: 99%