Prediction of excited‐state properties of oligoacene crystals using polarizable continuum model‐tuned range‐separated hybrid functional approach

Hu, Zhubin; Zhou, Bin; Sun, Zhenrong; Sun, Haitao

doi:10.1002/jcc.24736

Cited by 30 publications

(43 citation statements)

References 63 publications

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“…Theoretical studies of TADF molecules taking into account a solid-state environment have so far been limited. Our group recently developed a methodology, [16][17][18] the polarizable continuum model (PCM) 19 -tuned approach, in which optimal tuning of the range-separation parameter in a longrange corrected functional 16,[20][21][22][23] is combined with the description of the solid-state screening effects via the consideration of the solid-state dielectric constant (ε) in the context of the PCM approach (see Computational Details in the Supporting Information, SI). Our original work has…”

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confidence: 99%

“…shown that the accuracy of this methodology in calculating the solid-state ionization potential (IP), electron affinity (EA), transport gap, polarization energy, and exciton binding energy values, is comparable to that of state-of-the-art many-body perturbation theory within the GW approximation, with the results in excellent agreement with experimental data. [16][17][18] In this Letter, we apply this methodology to evaluate the singlet-triplet gap of four representative organic compounds (shown in Figure 1) as a function of the solid-state environment (for the sake of comparison, calculations were also performed with the widely used B3LYP functional). We have considered two TADF donor-acceptor-like molecules, TXO-TPA and TXO-PhCz, see Figure 1, which combine a 9-H-thioxanthen-9-one-10,10-dioxide (TXO) acceptor unit and either triphenylamine (TPA) or N-phenylcarbazole (N-PhCz) as a donor unit; these were taken from the work of Wang et al 7 In addition, we have investigated PXZ-TRZ (10-(4-(4,6-diphenyl-1,3,5triazin-2-yl)phenyl)-10H-phenoxazine), which has been reported to have a very small ΔE ST of ~0.06 eV 6 , as well as CBP (4,4'-bis(carbazol-9-yl)-p-biphenyl), which has a large ΔE ST of ~0.71 eV 6 (we note that CBP is not a TADF molecule and is usually employed as a hole-transporting material in conventional OLEDs).…”

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confidence: 99%

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Impact of Dielectric Constant on the Singlet–Triplet Gap in Thermally Activated Delayed Fluorescence Materials

Sun

Zhong

et al. 2017

J. Phys. Chem. Lett.

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134

142

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Thermally activated delayed fluorescence (TADF) relies on the presence of a very small energy gap, ΔE, between the lowest singlet and triplet excited states. ΔE is thus a key factor in the molecular design of more efficient materials. However, its accurate theoretical estimation remains challenging, especially in the solid state due to the influence of polarization effects. We have quantitatively studied ΔE as a function of dielectric constant, ε, for four representative organic molecules using the methodology we recently proposed at the Tamm-Dancoff approximation ωB97X level of theory, where the range-separation parameter ω is optimized with the polarizable continuum model. The results are found to be in very good agreement with experimental data. Importantly, the polarization effects can lead to a marked reduction in the ΔE value, which is favorable for TADF applications. This ΔE decrease in the solid state is related to the hybrid characters of the lowest singlet and triplet excited states, whose dominant contribution switches to charge-transfer-like with increasing ε. The present work provides a theoretical understanding on the influence of polarization effect on the singlet-triplet gap and confirms our methodology to be a reliable tool for the prediction and development of novel TADF materials.

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confidence: 99%

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confidence: 99%

Impact of Dielectric Constant on the Singlet–Triplet Gap in Thermally Activated Delayed Fluorescence Materials

Sun

Zhong

et al. 2017

J. Phys. Chem. Lett.

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134

142

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“…In the gas phase, the optimized system‐dependent parameters of subPC and anthracene are 0.16 and 0.22 Bohr −1 , respectively. Compared to the previous results, the optimized ω of anthracene is almost identical to the value by Sun et al [ 40 ] In addition, for comparison, we also selected the M06HF density functional to calculate the monomer and dimers of anthracene. M06HF is one of the M06 suite of meta‐hybrid generalized gradient approximation density functionals and has 100% Hatree‐Fock (HF) exchange.…”

Section: Methodsmentioning

confidence: 73%

On the study of influence of molecular arrangements and dipole moment on exciton binding energy in solid state

Xue

Zheng

2020

Int J of Quantum Chemistry

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Exciton binding energy (Eb) is one of the key factors affecting charge transfer and charge separation in organic solar cells (OSCs). However, most studies on Eb only focus on a single molecule, which is far from the real situation. How molecular arrangements and dipole moment influence Eb in solid state is still an open question. In the present work, a methodology combining the polarizable continuum model with calculated static dielectric constants, optimally tuned long‐range corrected hybrid density functional, and corrected optical gap is proposed for the calculations of Ebs with high accuracy. We have chosen boron subphthalocyanine chloride (subPC) with a strong dipole moment and anthracene without a dipole moment as two representative examples. To simulate solid‐state environmental effects better, different molecular dimers have been built up to simulate molecular arrangements. The most striking finding is that molecular arrangements and dipole moment have evident effects on Ebs. The calculated Ebs of anthracene in dimers are always smaller than that obtained with a single‐molecule model. In contrast, the Ebs of subPC dimers are generally larger (up to 30%) than that of subPC monomer; however, one exception is the convex‐to‐concave dimer configuration with the largest dipole moment, which has a smaller Eb by 5% than the monomer. These findings provide a guideline for the morphology control of thin film to improve the performance of OSC.

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“…This quantity, corresponding to the difference between the electronic gap and the excitation energy, is most accurately estimated from the solution of the BSE [83][84][85][86][87][88][89] on top of the GW approximation for the electronic self-energy. However, mainly due to (partial) error compensation (see details in the SI), TDDFT results obtained with a range-separated hybrid functional can provide a reliable estimate of this quantity [90][91][92][93][94][95][96] for the purpose of this work. In order to corroborate the reliability of our results, a direct comparison between the optical spectra computed from MBPT and hybrid TDDFT for the pristine molecules in vacuo is reported in the Supporting Information.…”

Section: Optical Propertiesmentioning

confidence: 99%

Electronic and Optical Properties of Protonated Triazine Derivatives

Guerrini,

Aznar,

Cocchi

2020

Preprint

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The peculiar electronic and optical properties of covalent organic frameworks (COFs) are largely determined by protonation, a ubiquitous phenomenon in the solution environment in which they are synthesized. The resulting effects are non-trivial and appear to be crucial for the intriguing functionalities of these materials. In the quantummechanical framework of time-dependent density-functional theory, we investigate from first principles the impact of protonation of triazine and amino groups in molecular building blocks of COFs in water solution. In all considered cases, we find that proton uptake leads to a gap reduction and to a reorganization of the electronic structure, driven by the presence of the proton and by the electrostatic attraction between the positively charged protonated species and the negative counterion in its vicinity.Structural distortions induced by protonation are found to play only a minor role. The interplay between band-gap renormalization and exciton binding strength determines the energy of the absorption onsets: when the former prevails on the latter, a red-shift is observed. Furthermore, the spatial and energetic rearrangement of the molecular orbitals upon protonation induces a splitting of the lowest-energy peaks and a decrease of their oscillator strength in comparison with the pristine counterparts. Our results offer quantitative and microscopic insight into the role of protonation on the electronic and optical properties of triazine derivatives as building blocks of COFs. As such, they contribute to rationalize the relationships between structure, property, and functionality of these materials.

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Prediction of excited‐state properties of oligoacene crystals using polarizable continuum model‐tuned range‐separated hybrid functional approach

Cited by 30 publications

References 63 publications

Impact of Dielectric Constant on the Singlet–Triplet Gap in Thermally Activated Delayed Fluorescence Materials

Impact of Dielectric Constant on the Singlet–Triplet Gap in Thermally Activated Delayed Fluorescence Materials

On the study of influence of molecular arrangements and dipole moment on exciton binding energy in solid state

Electronic and Optical Properties of Protonated Triazine Derivatives

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