Tuning the donors to control the lifetimes of charge-separated states in triazine-based donor-acceptor systems

Lü, Ting; Sun, Haiya; Colley, Nathan D.; Bridgmohan, Chelsea N.; Liu, Dongzhi; Li, Wei; Hu, Wenping; Zhou, Xueqin; Wang, Tianyang; Wang, Lichang

doi:10.1016/j.dyepig.2016.08.042

Cited by 21 publications

(9 citation statements)

References 60 publications

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“…Triazine is a potent electron acceptor that, owing to its three-fold symmetry, is increasingly found in multibranched and starshaped donor−acceptor (D−A) architectures. 1−15 These molecules are highly promising from the perspective of materials science for their high two-photon absorption cross sections, 3,4,9,13 long-lived charge-separated states, 10,15 for sensing applications, and as nonlinear near-IR antennae, 11 to name a few recent developments. Therefore, much effort is dedicated toward the design of triazine-containing architectures with optimal properties toward the above-mentioned applications.…”

Section: ■ Introductionmentioning

confidence: 99%

Direct Observation of a Photochemical Alkyne–Allene Reaction and of a Twisted and Rehybridized Intramolecular Charge-Transfer State in a Donor–Acceptor Dyad

Dereka

Svechkarev²,

Rosspeintner

et al. 2017

J. Am. Chem. Soc.

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The excited-state dynamics of an aniline-triazine electron donor-acceptor dyad with an alkyne spacer has been investigated using a combination of ultrafast broadband mid-IR and visible transient absorption and fluorescence spectroscopies. The transient IR data reveal the occurrence of an efficient alkyne to allene isomerization of the spacer with a time constant increasing from a few hundreds of femtoseconds to a few picoseconds with solvent viscosity. This process is faster than the vibrational cooling of the Franck-Condon excited state, indicative of nonequilibrium dynamics. The transient electronic absorption and fluorescence data evidence that this transformation is accompanied by a charge separation between the donor and the acceptor subunits. The allene character of the spacer implies an orthogonal orientation of the donor and acceptor moieties, similar to that proposed for twisted intramolecular charge-transfer states. Such states are often invoked in the excited-state dynamics of donor-acceptor dyads, but their involvement could never be unambiguously evidenced spectroscopically. The alkyne-allene isomerization involves not only a torsional motion but also a bending of the molecule due to the sp to sp rehybridization of one of the alkyne carbon atoms. This twisted and rehybridized intramolecular charge transfer ("TRICT") state decays back to the planar and linear alkyne ground state on a time scale decreasing from a few hundred to ten picoseconds upon going from weakly to highly polar solvents. The different solvent dependencies reveal that the dynamics of the allene buildup are controlled by the structural changes, whereas the decay is limited by the charge recombination step.

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Section: ■ Introductionmentioning

confidence: 99%

Direct Observation of a Photochemical Alkyne–Allene Reaction and of a Twisted and Rehybridized Intramolecular Charge-Transfer State in a Donor–Acceptor Dyad

Dereka

Svechkarev²,

Rosspeintner

et al. 2017

J. Am. Chem. Soc.

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“…The absorption maxima of MTPA and YD are derived from the transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) which has been discovered with PCT character from the triphenylamine or indole to the styrene module. 54 The minor red shift of the λ abs max of MTPA-Pyc and YD-Pyc suggests that the corresponding transitions of these CS sensitizers are similar to those of the donor modules MTPA and YD. 44,46 This is further confirmed by the calculation results shown in Figure 3 in which the transition energy of the CS sensitizers corresponding to the major absorption band of the calculated absorption spectra is in good accordance with the HOMO− LUMO+1 energy gap.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

Enhanced Internal Quantum Efficiency in Dye-Sensitized Solar Cells: Effect of Long-Lived Charge-Separated State of Sensitizers

Sun

Liu

Wang

et al. 2017

ACS Appl. Mater. Interfaces

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Effective charge separation is one of the key determinants for the photovoltaic performance of the dye-sensitized solar cells (DSSCs). Herein, two charge-separated (CS) sensitizers, MTPA-Pyc and YD-Pyc, have been synthesized and applied in DSSCs to investigate the effect of the CS states of the sensitizers on the device's efficiency. The CS states with lifetimes of 64 and 177 ns for MTPA-Pyc and YD-Pyc, respectively, are formed via the photoinduced electron transfer (PET) from the 4-styryltriphenylamine (MTPA) or 4-styrylindoline (YD) donor to the pyrimidine cyanoacrylic acid (Pyc) acceptor. DSSCs based on MTPA-Pyc and YD-Pyc exhibit high internal quantum efficiency (IQE) values of over 80% from 400 to 600 nm. In comparison, the IQEs of the charge transfer (CT) sensitizer cells are 10-30% lower in the same wavelength range. The enhanced IQE values in the devices based on the CS sensitizers are ascribed to the higher electron injection efficiencies and slower charge recombination. The results demonstrate that taking advantage of the CS states in the sensitizers can be a promising strategy to improve the IQEs and further enhance the overall efficiencies of the DSSCs.

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“…Triazine is a potent electron acceptor that, owing to its three-fold symmetry, is increasingly found in multibranched and star-shaped donor-acceptor architectures. [286][287][288][289][290][291][292][293][294][295][296][297][298][299][300] Much effort has been dedicated recently toward the design of triazine-containing molecules with optimal properties toward materials science applications. 288,289,[294][295][296]298,300 The current approach to synthesize such F systems is typically based on the intramolecular coupling of strong electron donors with the triazine cores to impart a charge-transfer character.…”

Section: Chapter 8 a Photochemical Reactionmentioning

confidence: 99%

“…[286][287][288][289][290][291][292][293][294][295][296][297][298][299][300] Much effort has been dedicated recently toward the design of triazine-containing molecules with optimal properties toward materials science applications. 288,289,[294][295][296]298,300 The current approach to synthesize such F systems is typically based on the intramolecular coupling of strong electron donors with the triazine cores to impart a charge-transfer character. Surprisingly, no comprehensive photophysical study still exists to date addressing the excited-state dynamics of triazine-based donor-acceptor systems.…”

Section: Chapter 8 a Photochemical Reactionmentioning

confidence: 99%

Excited-state symmetry breaking: from fundamental photophysics to asymmetrical photochemistry

Dereka¹

2021

Photochemistry

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Tuning the donors to control the lifetimes of charge-separated states in triazine-based donor-acceptor systems

Cited by 21 publications

References 60 publications

Direct Observation of a Photochemical Alkyne–Allene Reaction and of a Twisted and Rehybridized Intramolecular Charge-Transfer State in a Donor–Acceptor Dyad

Direct Observation of a Photochemical Alkyne–Allene Reaction and of a Twisted and Rehybridized Intramolecular Charge-Transfer State in a Donor–Acceptor Dyad

Enhanced Internal Quantum Efficiency in Dye-Sensitized Solar Cells: Effect of Long-Lived Charge-Separated State of Sensitizers

Excited-state symmetry breaking: from fundamental photophysics to asymmetrical photochemistry

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