Accelerating symmetry-breaking charge separation in a perylenediimide trimer through a vibronically coherent dimer intermediate

Nature Chemistry, Journal Year: 2022, Volume and Issue: 14(7), P. 786 - 793

Published: April 25, 2022

Language: Английский

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Symmetry-Breaking Charge Separation and Null Aggregates

The Journal of Physical Chemistry C, Journal Year: 2024, Volume and Issue: 128(1), P. 248 - 260

Published: Jan. 2, 2024

The relationship between symmetry-breaking charge separation (SB-CS) and null aggregate (NA) formation in molecular dimer complexes is investigated theoretically, with applications mainly to dimers based on PDI chromophores. Both processes derive from points, which are defined by degeneracies either the upper or lower adiabatic exciton bands. Hamiltonian contains intermolecular coupling derived interacting transition dipole moments (Coulomb coupling), gives rise Frenkel excitons, as well excitons charge-transfer (CT) driven electron (te) hole (th) hopping integrals. A recipe for efficient SB-CS presented, which, beyond Weller condition─which holds that solvent-stabilized CT state should appear below optical gap -includes two additional conditions: presence of a point and, just important, lopsided transfer integrals, |te| ≫ |th| |te|. When such conditions met, developing asymmetry optimized response small fluctuations polar solvent-induced electric field, eventually leads charge-separated state. It shown can also occur H-dimers significant cofacial overlap, consistent observations made several groups.

Language: Английский

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Symmetry-Breaking Charge Separation in Molecular Constructs for Efficient Light Energy Conversion

ACS Energy Letters, Journal Year: 2022, Volume and Issue: 7(2), P. 696 - 711

Published: Jan. 26, 2022

The generation of electron–hole radical pair at the active layer organic photovoltaics through symmetry-breaking charge separation (SB-CS) has a crucial role in enhancing open-circuit voltage (Voc) and thereby increasing power conversion efficiency. Since SB-CS materials achieve intramolecular with negligible energetic driving force decelerated recombination (CR) rate, been subjected to extensive experimental theoretical studies. This Focus Review assesses fundamentals photosynthetic reaction centers, especially "special pair", discusses how covalent control over geometric arrangement, surrounding dielectric medium, substitutions on multichromophoric perylenediimide architecture affects energy landscape CR. We systematically summarize kinetically favored undesirable radiative non-radiative deactivation channels CR processes diverse chromophoric arrangements. Here, we suggest new rational design principles fine-tune electron-transfer dynamics molecular level improve performance light–energy devices.

Language: Английский

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Through‐Space Charge Transfer: A New Way to Develop a High‐Performance Fluorescence Sensing Film towards Opto‐Electronically Inert Alkanes

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(35)

Published: July 1, 2022

Abstract New strategies are in high demand for fast, sensitive, selective, on‐site and real‐time detection of the important but challenging alkane vapors owing to their opto‐electronic inertness. Herein, we report, first time, a high‐performance fluorescent film sensor (FFS) alkanes with rationally designed through‐space charge transfer (TSCT) molecule as sensing fluorophore. Steady‐state fluorescence, femto‐second transient absorption spectroscopy theoretical studies revealed continuous TSCT dynamics excited U‐shaped increasing medium polarity. Furthermore, interlocked, face‐to‐face alignment between donor acceptor favors mass transport analyte molecules state. As anticipated, compound‐based FFS showed an experimental limit ≈10 ppm n ‐pentane, less than 5 s full detection, negligible interference super‐stability, revealing effectiveness design strategy. Notably, is small (≈3.7 cm 3 ), power‐saving, workable at room temperature.

Language: Английский

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Ultrafast Symmetry-Breaking Charge Separation in a Perylene Bisimide Dimer Enabled by Vibronic Coupling and Breakdown of Adiabaticity

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(34), P. 15539 - 15548

Published: Aug. 11, 2022

Perylene bisimides (PBIs) have received great attention in their applicability to optoelectronics. Especially, symmetry-breaking charge separation (SB-CS) PBIs has been investigated mimic the efficient light capturing and generation natural light-harvesting systems. However, unlike ultrafast CS dynamics donor-acceptor heterojunction materials, SB-CS a stacked homodimer still challenging due excimer formation absence of rigidifying surroundings such as special pair Herein, we present detailed mechanism photoinduced occurring 1,7-bis(N-pyrrolidinyl) PBI dimer within cyclophane. Through narrow-band broad-band transient absorption spectroscopy, demonstrate that is enabled by combination (1) vibrationally coherent charge-transfer resonance-enhanced (2) breakdown adiabaticity (formation diabats) state via structural solvent fluctuation. Quantum chemical calculations also underpin participation strong electron-donating substituents overall vibrational modes plays crucial role triggering SB-CS. Therefore, our work provides an alternative route facilitate thereby establishes novel strategy for design optoelectronic materials.

Language: Английский

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Keeping the chromophores crossed: evidence for null exciton splitting

Chemical Society Reviews, Journal Year: 2023, Volume and Issue: 52(19), P. 6664 - 6679

Published: Jan. 1, 2023

Attempts to identify and probe atypical molecular aggregates focusing on the less explored null aggregates. The aggregate was foretold by Kasha possess exciton interaction leading spectroscopically uncoupled assembly.

Language: Английский

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Controlling Symmetry Breaking Charge Transfer in BODIPY Pairs

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 55(11), P. 1561 - 1572

Published: May 23, 2022

ConspectusSymmetry breaking charge transfer (SBCT) is a process in which pair of identical chromophores absorb photon and use its energy to an electron from one chromophore the other, symmetry pair. This excited state phenomenon observed photosynthetic organisms where it enables efficient formation separated charges that ultimately catalyze biosynthesis. SBCT has also been proposed as means for developing photovoltaics photocatalytic systems operate with minimal loss. It known both biological artificial part made possible by local environment occurs, can move stabilize asymmetric state. However, how environmental degrees freedom act concert steric structural constraints placed on dictate ability generate long-lived pairs via remain open topics investigation.In this Account, we compare broad series dipyrrin dimers are linked distinct bridging groups discern spatial separation mutual orientation flexibility their linker each impact efficiency. Across material set, observe general trend accelerated between dimer decreases, consistent expectation electronic coupling these units varies exponentially separation. key observation rate recombination following was found slow decreasing interchromophore separation, rather than speed up. stems enhancement dimer's rigidity due increasing repulsion length shrinks. further inhibits already enforced zero HOMO–LUMO overlap. Additionally, forward transfer, active torsion shown increase LUMO–LUMO coupling, allowing faster within groups.By understanding trends rates depend internal structure environment, identify design guidelines creating driving sustained light-induced Such find application solar technologies applications serve model systems.

Language: Английский

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π-Stacking-Dependent Vibronic Couplings Drive Excited-State Dynamics in Perylenediimide Assemblies

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(25), P. 11386 - 11396

Published: June 14, 2022

Vibronic coupling, the interplay of electronic and nuclear vibrational motion, is considered a critical mechanism in photoinduced reactions such as energy transfer, charge singlet fission. However, our understanding how particular vibronic couplings impact excited-state dynamics lacking due to limited number experimental studies model molecular systems. Herein, we use two-dimensional spectroscopy (2DES) launch interrogate range coherences two distinct types perylenediimide slip stacks─along short long axes, which form either an excimer or mixed state between Frenkel exciton (FE) transfer states. We explore functionality these using quantum beatmaps, display Fourier amplitude signal oscillations function pump probe frequencies, along with knowledge characteristic signatures FE, ionic, species. find that low-frequency mode short-axis stack appears concomitantly formation state, survives 2-fold longer than FE reference monomer, shows phase shift compared other modes. For long-axis stacks, pair modes coupled high-frequency coordinate were found play role mixed-state generation. Our findings thus experimentally reveal complex varying roles tightly packed multimers undergoing processes.

Language: Английский

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Excimer evolution hampers symmetry-broken charge-separated states

Chemical Science, Journal Year: 2022, Volume and Issue: 13(36), P. 10824 - 10835

Published: Jan. 1, 2022

Achieving long-lived symmetry-broken charge-separated states in chromophoric assemblies is quintessential for enhanced performance of artificial photosynthetic mimics. However, the occurrence energy trap hinders exciton and charge transport across photovoltaic devices, diminishing power conversion efficiency. Herein, we demonstrate unprecedented excimer formation relaxed excited-state geometry bichromophoric systems impeding lifetime states. Core-annulated perylenediimide dimers (SC-SPDI2 SC-NPDI2) prefer a near-orthogonal arrangement ground state π-stacked foldamer structure excited state. The prospect an excimer-like foldameric SC-SPDI2 SC-NPDI2 has been rationalized by fragment-based analysis temperature-dependent photoluminescence measurements. Effective electronic coupling matrix elements Franck-Condon facilitate solvation-assisted ultrafast symmetry-breaking charge-separation (SB-CS) high dielectric environment, contrast to unrelaxed (Ex*) low environment. Subsequently, SB-CS dissociates into undesired (Ex) due configuration mixing Frenkel (FE) structure, downgrading efficacy decay rate constant FE (kFE→SB-CS) polar solvents 8-17 fold faster than that direct Ex* (kFE→Ex*) non-polar solvent (kFE→SB-CS≫kFE→Ex*), characterized femtosecond transient absorption (fsTA) spectroscopy. present investigation establishes impact detrimental on persistence offers requisite conformational rigidity as one potential design principles developing advanced molecular photovoltaics.

Language: Английский

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Advances in Molecular Design and Photophysical Engineering of Perylene Bisimide-Containing Polyads and Multichromophores for Film-Based Fluorescent Sensors

The Journal of Physical Chemistry B, Journal Year: 2023, Volume and Issue: 127(4), P. 828 - 837

Published: Jan. 24, 2023

Film-based fluorescent sensors (FFSs) represent an important chemistry technology for meeting the urgent needs of on-site and real-time analysis, thereby enabling significant applications in environmental health monitoring. As core FFSs, innovative design sensing fluorophores their intrinsic excited-state-related response nature endow FFSs with superior performances endless expansion. In this Perspective, we specifically focus on perylene bisimide (PBI)-containing polyads multichromophores rigid configuration notable photochemical stability developing high-performance FFSs. These nonplanar structures mitigate aggregation create abundant gaps sake mass transfer availability units adlayer films. We also comprehensively discuss how to adjust electronic coupling governing excited-state events by appropriate functionalization strategies, thus providing a plethora valuable insights exploration structure-property relationships these orchestrated molecular systems. Throughout identify opportunities future developments.

Language: Английский

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