Enthalpy–Entropy Compensation Effect for Triplet Pair Dissociation of Intramolecular Singlet Fission in Phenylene Spacer-Bridged Hexacene Dimers

2021 ◽  
pp. 6457-6463
Author(s):  
Shunta Nakamura ◽  
Hayato Sakai ◽  
Masaaki Fuki ◽  
Yasuhiro Kobori ◽  
Nikolai V. Tkachenko ◽  
...  
Keyword(s):  
Compensation Effect ◽  
Singlet Fission ◽  
Triplet Pair

scholarly journals Ultrafast Triplet Pair Separation and Triplet Trapping following Singlet Fission in Amorphous Pentacene Films

2020 ◽  
Vol 124 (43) ◽  
pp. 23567-23578
Author(s):  
Kyle T. Munson ◽  
Jianing Gan ◽  
Christopher Grieco ◽  
Grayson S. Doucette ◽  
John E. Anthony ◽  
...  
Keyword(s):  
Singlet Fission ◽  
Pair Separation ◽  
Triplet Pair

scholarly journals Uncovering dark multichromophoric states in Peridinin–Chlorophyll–Protein

2020 ◽  
Vol 17 (164) ◽  
pp. 20190736
Author(s):  
Elliot J. Taffet ◽  
Francesca Fassioli ◽  
Zi S. D. Toa ◽  
David Beljonne ◽  
Gregory D. Scholes
Keyword(s):  
Crystal Structure ◽  
Excited States ◽  
Quantum Chemical ◽  
Light Harvesting ◽  
Singlet Fission ◽  
Chlorophyll Protein ◽  
Triplet Pair ◽  
A Charge ◽  
Hole Generation ◽  
Chemical Evidence

It has long been recognized that visible light harvesting in Peridinin–Chlorophyll–Protein is driven by the interplay between the bright (S 2 ) and dark (S 1 ) states of peridinin (carotenoid), along with the lowest-lying bright (Q y ) and dark (Q x ) states of chlorophyll- a . Here, we analyse a chromophore cluster in the crystal structure of Peridinin–Chlorophyll–Protein, in particular, a peridinin–peridinin and a peridinin–chlorophyll- a dimer, and present quantum chemical evidence for excited states that exist beyond the confines of single peridinin and chlorophyll chromophores. These dark multichromophoric states, emanating from the intermolecular packing native to Peridinin–Chlorophyll–Protein, include a correlated triplet pair comprising neighbouring peridinin excitations and a charge-transfer interaction between peridinin and the adjacent chlorophyll- a . We surmise that such dark multichromophoric states may explain two spectral mysteries in light-harvesting pigments: the sub-200-fs singlet fission observed in carotenoid aggregates, and the sub-200-fs chlorophyll- a hole generation in Peridinin–Chlorophyll–Protein.

scholarly journals Elucidation of Excitation Energy Dependent Correlated Triplet Pair Formation Pathways in an Endothermic Singlet Fission System

2017 ◽  
Vol 140 (13) ◽  
pp. 4613-4622 ◽  
Author(s):  
Arya Thampi ◽  
Hannah L. Stern ◽  
Alexandre Cheminal ◽  
Murad J. Y. Tayebjee ◽  
Anthony J. Petty ◽  
...  
Keyword(s):  
Excitation Energy ◽  
Pair Formation ◽  
Singlet Fission ◽  
Triplet Pair ◽  
Energy Dependent

scholarly journals Porous Shape-Persistent Rylene Imine Cages with Tunable Optoelectronic Properties and Delayed Fluorescence

2020 ◽  
Author(s):  
Hsin-Hua Huang ◽  
Kyung Seob Song ◽  
Alessandro Prescimone ◽  
Rajesh Mannancherry ◽  
Ali Coskun ◽  
...  
Keyword(s):  
Excited State ◽  
Electronic Properties ◽  
Green Light ◽  
Delayed Fluorescence ◽  
Optoelectronic Properties ◽  
Covalent Organic Frameworks ◽  
Singlet Fission ◽  
Triplet Pair ◽  
Material Porosity

A simultaneous combination of porosity and tunable optoelectronic properties, common in covalent organic frameworks, are rare in shape-persistent organic cages. Yet, organic cages offer important molecular advantages, the solubility and modularity. Herein, we report the synthesis of a series of chiral imine organic cages with three built-in rylene units by means of dynamic imine chemistry and we investigate their textural and optoelectronic properties. Thereby we demonstrate that the synthesized rylene cages are porous, can be reversibly reduced at accessible potentials, and can absorb from UV up to green light. We also show that they preferentially adsorb CO2 over N2 and CH4 with a good selectivity. In addition, we discovered that the cage incorporating three perylene-3,4:9,10-bis(dicarboximide) units displays a delayed fluorescence, likely as a consequence of formation of a correlated triplet pair, the multiexciton state in singlet fission. Rylene cages thus represent a unique platform to investigate the effect of electronic properties on material porosity and, at the same time, to probe excited-state phenomena in the limit of vanishing interchromophore coupling. <br>

scholarly journals Revealing the contest between triplet-triplet exchange and triplet-triplet energy transfer coupling in correlated triplet pair states in singlet fission

2021 ◽  
Author(s):  
Vibin Abraham ◽  
Nicholas Mayhall
Keyword(s):  
Energy Transfer ◽  
Exchange Interaction ◽  
Entangled State ◽  
Separation Mechanism ◽  
Singlet Fission ◽  
Triplet Energy ◽  
Triplet Pair ◽  
Triplet Energy Transfer ◽  
State 1 ◽  
Pair State

Understanding the separation of the correlated triplet pair state 1(TT) intermediate is critical for leveraging singlet fission to improve solar cell efficiency. This separation mechanism is dominated by two key interactions: (i) the exchange interaction (K) between the triplets which leads to the spin splitting of the biexciton state into 1(TT),3(TT) and 5(TT) states, and (ii) the triplet-triplet energy transfer integral (t) which enables the formation of the spatially separated (but still spin entangled) state 1(T...T). We develop a simple ab initio technique to compute both the biexciton exchange (K) and biexciton transfer coupling. Our key findings reveal new conditions for successful correlated triplet pair state dissociation. The biexciton exchange interaction needs to be ferromagnetic or negligible to the triplet energy transfer for favourable dissociation. We also explore the effect of chromophore packing to reveal geometries where these conditions are achieved for tetracene.

scholarly journals Influence of the heavy-atom effect on singlet fission: a study of platinum-bridged pentacene dimers

2019 ◽  
Vol 10 (48) ◽  
pp. 11130-11140 ◽  
Author(s):  
Bettina S. Basel ◽  
Ryan M. Young ◽  
Matthew D. Krzyaniak ◽  
Ilias Papadopoulos ◽  
Constantin Hetzer ◽  
...  
Keyword(s):  
Heavy Atom ◽  
Singlet Fission ◽  
Heavy Atom Effect ◽  
Triplet Pair ◽  
Atom Effect

Two platinum-bridged pentacene dimers undergo efficient singlet fission to form a correlated triplet pair (T1T1). The internal heavy-atom effect of the platinum allows for 1(T1T1)–3(T1T1) mixing leading to the formation of mainly (T1S0).

Long-lived Triplet Excitons Formed by Exergonic Intramolecular Singlet Fission of an Adamantane-linked Tetracene Dyad

2019 ◽  
Author(s):  
Yasunori Matsui ◽  
Shuhei Kawaoka ◽  
Hiroki Nagashima ◽  
Tatsuo Nakagawa ◽  
Naoki Okamura ◽  
...  
Keyword(s):  
Conformational Dynamics ◽  
High Energy ◽  
Fluorescence Decay ◽  
Singlet Fission ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
Triplet Pair ◽  
Electron Paramagnetic ◽  
Effective Conservation ◽  
Moderate Interaction

<div>An adamantane-linked tetracene dyad (Tc–Ad–Tc) undergoes exergonic intramolecular singlet fission (SF), producing longlived (τ = 175 μs) and high-energy (2 x 1.03 eV) multiexcitons. Timeresolved absorption, fluorescence decay, and electron paramagnetic resonance (EPR) spectroscopic analysis revealed that the long-lived triplet species is generated in this system via correlated triplet pair having singlet and quintet characteristics. Time-resolved EPR analysis revealed that conversion of <sup>1</sup>(<sup>3</sup>Tc–Ad–<sup>3</sup>Tc)* -> <sup>5</sup>(<sup>3</sup>Tc–Ad–<sup>3</sup>Tc)* requires small conformational dynamics accompanied by molecular motion. Analysis of the geometries of the quintet states shows that formation of the long-lived multiexciton is enabled by precise and close alignment of the tetracene moieties, which leads to their moderate interaction in the singlet excited state, while triplet–triplet annihilation is prevented by quintet generation. The presence of aliphatic linkages, like the rigid adamantane group, might enable effective conservation of intrinsic S<sub>1</sub> and T<sub>1</sub> levels of the original monomers, and moderate bridge-mediated σ–π interaction leading to exergonic intramolecular SF involving <sup>1</sup>Tc*–Ad–Tc -> <sup>1</sup>(<sup>3</sup>Tc–Ad–<sup>3</sup>Tc)*.</div><div><br></div>

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