Theoretical analysis of excited states and energy transfer mechanism in conjugated dendrimers

Huang, Jing; Du, Likai; Da, Hu; Lan, Zhenggang

doi:10.1002/jcc.23778

Cited by 29 publications

(35 citation statements)

References 99 publications

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“…In a more general sense, the problem can be traced back to correlation effects between the electron and hole quasi‐particles . A number of strategies to overcome this problem have been introduced by different authors but their application is still quite limited …”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of electronic excitation processes: Spatial location, compactness, charge transfer, and electron-hole correlation

et al. 2015

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We report the development of a set of excited-state analysis tools that are based on the construction of an effective exciton wavefunction and its statistical analysis in terms of spatial multipole moments. This construction does not only enable the quantification of the spatial location and compactness of the individual hole and electron densities but also correlation phenomena can be analyzed, which makes this procedure particularly useful when excitonic or charge-resonance effects are of interest. The methods are first applied to bianthryl with a focus on elucidating charge-resonance interactions. It is shown how these derive from anticorrelations between the electron and hole quasiparticles, and it is discussed how the resulting variations in state characters affect the excited-state absorption spectrum. As a second example, cytosine is chosen. It is illustrated how the various descriptors vary for valence, Rydberg, and core-excited states, and the possibility of using this information for an automatic characterization of state characters is discussed.

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Section: Introductionmentioning

confidence: 99%

Statistical analysis of electronic excitation processes: Spatial location, compactness, charge transfer, and electron-hole correlation

et al. 2015

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“…[28][29][30] In the case of molecules with extended π systems it has been understood for a while that non-standard analysis methods are particularly valuable, and these have been applied successfully by various groups. [10][11][12][31][32][33][34][35][36] It has been our aim to supply a formalism that allows to analyze the wavefunctions of interacting chromophores and extended systems in a general quantum chemical context. Whereas our work was initially based on phenomenological reasoning, 17 we have recently embedded our approach in a more solid formalism within exciton theory.…”

Section: Introductionmentioning

confidence: 99%

Entanglement entropy of electronic excitations

Plasser

2016

The Journal of Chemical Physics

106

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A new perspective into correlation effects in electronically excited states is provided through quantum information theory. The entanglement between the electron and hole quasiparticles is examined, and it is shown that the related entanglement entropy can be computed from the eigenvalue spectrum of the well-known natural transition orbital (NTO) decomposition. Non-vanishing entanglement is obtained whenever more than one NTO pair is involved, i.e., in the case of a multiconfigurational or collective excitation. An important implication is that in the case of entanglement it is not possible to gain a complete description of the state character from the orbitals alone, but more specific analysis methods are required to decode the mutual information between the electron and hole. Moreover, the newly introduced number of entangled states is an important property by itself giving information about excitonic structure. The utility of the formalism is illustrated in the cases of the excited states of two interacting ethylene molecules, the conjugated polymer para-phenylene vinylene, and the naphthalene molecule.

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“…Furthermore, the transition density matrix T EG, [Lo] is formed in the orthogonal Loẅdin orbital basis by 37 …”

Section: ■ Theoretical Methodsmentioning

confidence: 99%

Photoinduced Excited-State Energy-Transfer Dynamics of a Nitrogen-Cored Symmetric Dendrimer: From the Perspective of the Jahn–Teller Effect

Huang

Wang

et al. 2015

J. Phys. Chem. C

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We report an interesting view to understand the ultrafast excited-state energy-transfer (EET) process in the D 3 -symmetric dendrimer tris(4-ethynylphenyl)amine (TEPA) from the perspective of the well-known E⊗e Jahn−Teller (JT) effect. Upon excitation to two lowest excited states (S 1 and S 2 ) with doubly degenerate E symmetry, two sets of e vibrational modes, dihedral angle twist and strong pyramidalization near the nitrogen core, lead to the JT distortion and symmetry lowering. Through the excited-state dynamics simulation with the onthe-fly surface-hopping approach at the TDDFT level, we find that the system may either travel three equivalent minima of S 1 state or undergo the nonadiabatic transitions between S 1 and S 2 states. These motions induce the ultrafast EET among different branches and the reorientation of the transition dipole moments, finally leading to the ultrafast fluorescence anisotropy decay. This energy-transfer mechanism can provide some interesting insights on the excited-state dynamics of large dendrimers with three equivalent branches and transition metal complexes with C 3 symmetry. ■ INTRODUCTIONOrganic dendrimers show attractive photovoltaic properties such as efficient photoharvesting, 1,2 unidirectional energy transfer, 3 enhanced two-photon absorption, 4−6 and high photoluminescence quantum yield. 7,8 These properties make them potentially useful in photovoltaic materials for solar energy conversion, 1,3,9 fluorescence sensors, 10,11 organic lightemitting diodes, 12,13 and organic lasers. 8,14 The fundamental photophysics and photochemistry of these novel dendritic macromolecular architectures involve the exciton formation and movement (localization or delocalization), 15−18 especially the intramolecular excited-state energy transfer (EET) between different subunits (branches). 3,19−22 A number of experimental studies have been carried out to study the intramolecular EET between different subunits for branched molecules. 23−25 In particular, the organic dendrimers with rotational symmetry (such as the existence of C 3 or C 4 rotational axes) have attracted considerable attention since the efficient EET is expected among those equivalent branches. With the development of laser technology, time-dependent fluorescence depolarization may provide useful information on the energy-transfer processes of such high-symmetric systems. 25−29 This special technology allows us to monitor the orientation change of the emission dipole with respect to the absorption dipole, which is caused by the variation of local excitation with time. Goodson III and collaborators studied the intramolecular EET mechanism of several dendrimers, such as T-NPTPA, 25,29 A-DSB, 30,31 G n , 32 and so on. With timeresolved spectroscopy, they reported that a group of tribranched molecules with a nitrogen core show a very fast energy transfer among different branches on the ∼30−100 fs time scale. Through the investigation of a series of branched molecules with similar building blocks (chromophores) and different core un...

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Theoretical analysis of excited states and energy transfer mechanism in conjugated dendrimers

Cited by 29 publications

References 99 publications

Statistical analysis of electronic excitation processes: Spatial location, compactness, charge transfer, and electron-hole correlation

Statistical analysis of electronic excitation processes: Spatial location, compactness, charge transfer, and electron-hole correlation

Entanglement entropy of electronic excitations

Photoinduced Excited-State Energy-Transfer Dynamics of a Nitrogen-Cored Symmetric Dendrimer: From the Perspective of the Jahn–Teller Effect

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