We apply a real-time path-integral approach to investigate the charge-transfer (CT)-mediated singlet fission quantum dynamics in a model pentacene dimer. Our path-integral method gives reliable fission dynamics across various reaction regimes as well as a broad range of reorganization energies and temperatures. With this method, we investigated the destructive interference between the two CT-mediated fission pathways and discovered two mechanisms that can suppress this deleterious effect. First, increasing the energy gap between the two CT states effectively shuts down the high-lying CT pathway, leaving a better functioning low-lying CT pathway with a minimum amount of destructive interference. Second, intermolecular vibrations induce electronic coupling fluctuations, such that the destructive cancellations due to the different signs in static electronic couplings are suppressed. Our numerical results suggest that these two effects can enhance the fission rate up to three times. These findings reveal promising design principles for more efficient singlet fission materials.
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http://dx.doi.org/10.1021/acs.jpclett.7b00972 | DOI Listing |
J Phys Chem A
January 2025
Institute of Physical and Theoretical Chemistry, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 42, Würzburg 97074, Germany.
Diffusion generative models, a class of machine learning techniques, have shown remarkable promise in materials science and chemistry by enabling the precise generation of complex molecular structures. In this article, we propose a novel application of diffusion generative models for stabilizing reactive molecular structures identified through quantum mechanical screening. Specifically, we focus on the design challenge presented by singlet fission (SF), a phenomenon crucial for advancing solar cell efficiency beyond theoretical limits.
View Article and Find Full Text PDFChemistry
January 2025
Shandong University, School of Chemistry and Chemical Engineering, 27 Shanda Nan Road, 250100, Jinan, CHINA.
Photophysical properties of condensed systems generally originate from collective contributions of all components in their stochastically fluctuated structures and are strongly influenced under strain of chromophores. To precisely identify how the stochastically fluctuated monomers synergistically manipulate the properties, we propose a statistic strategy over sufficient ab initio molecular dynamics (AIMD) samplings and for the first time uncover that synergistic oscillatory twisting (SOT) of neighboring under-strain monomers manipulates the bifunction of rubrene crystal. The under-strain trunk SOT can regulate both singlet fission (SF) and triplet-triplet annihilation (TTA), enabling their coexistence and dominance switching by dynamically modulating the matching of excitation energies.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, U.K.
Activated intramolecular singlet fission is known to occur in the conjugated polymer polythienylene-vinylene (P3TV). Instead, efficient intersystem crossing has been observed in a short 3-alkyl(thienylene-vinylene) dimer. Here, we investigate a series of oligomers covering the conjugation length gap between the dimer and polymer.
View Article and Find Full Text PDFAdv Mater
December 2024
Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
Singlet exciton fission has the potential to increase the efficiency of crystalline silicon solar cells beyond the conventional single junction limit. Perhaps the largest obstacle to achieving this enhancement is uncertainty about energy coupling mechanisms at the interfaces between silicon and exciton fission materials such as tetracene. Here, the previously reported silicon-hafnium oxynitride-tetracene structure is studied and a combination of magnetic-field-dependent silicon photoluminescence measurements and density functional theory calculations is used to probe the influence of the interlayer composition on the triplet transfer process across the hafnium oxynitride interlayer.
View Article and Find Full Text PDFChimia (Aarau)
December 2024
Dept. of Chemistry, Dept. of Physics and Astronomy, Dept. of Materials Science and Nanoengineering, Rice Advanced Materials Institute, Rice University, Houston, Texas 77005, USA.
Photon interconversion promises to alleviate thermalization losses for high energy photons and facilitates utilization of sub-bandgap photons - effectively enabling the optimal use of the entire solar spectrum. However, for solid-state device applications, the impact of intermolecular interactions on the energetic landscape underlying singlet fission and triplet-triplet annihilation upconversion cannot be neglected. In the following, the implications of molecular arrangement, intermolecular coupling strength and molecular orientation on the respective processes of solid-state singlet fission and triplet-triplet annihilation are discussed.
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