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Singlet fission (SF) is a triplet generation mechanism capable of turning a singlet exciton into two triplet excitons. It has the potential to enhance the power conversion efficiency of single-junction solar cells. Perylene diimides (PDIs) are a class of dye molecules with photovoltaic properties and are beginning to receive more and more attention due to their potential for SF. Here, we report a selenium-substituted PDI dimer, Se-PDI-II, and we studied its SF mechanism by using steady-state, transient absorption, and time-resolved photoluminescence spectroscopy. Compared with the unsubstituted dimer PDI-II, we found that the introduction of selenium atoms can suppress excimer emission during the SF process, showing much higher SF efficiency and triplet yield.
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http://dx.doi.org/10.1021/acs.jpcb.4c01744 | DOI Listing |
J Phys Chem Lett
September 2025
Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Understanding the electronic structure of polycyclic aromatic compounds is of fundamental importance for their potential applications. The optoelectronic properties of shorter acenes such as tetracene and pentacene have been extensively studied with regard to excitation, emission, and nonlinear effects such as singlet fission. The longer homologues present a unique challenge due to their low stability both in the solid state and in solution.
View Article and Find Full Text PDFJ Phys Chem A
August 2025
Department of Chemistry, Bhatter College, Dantan, P.O. Dantan, Paschim Medinipur, Dantan 721426, India.
Tetracyanoquinodimethane (TCNQ) and related compounds are thoroughly investigated as potential innovative organic semiconductors and singlet fission (SF) materials. The TDDFT method with the PBE0/Def2-TZVP level is used to determine the geometrical structures, atomic dipole corrected Hirshfeld (ADCH) charge, population, dipole moment (μ), band gaps, different density of states (DOSs), excitation energies, hole-(λ) and electron-(λ) reorganization energies, SF properties, absorption-emission spectra, transition density matrix (TDM), electron localization function (ELF) of these molecules, and open circuit voltage (), fill factor (FF), and power conversion efficiency (PCE) of possible optoelectronic devices. At the CAM-B3LYP/6-311G** level, we examine the ground and excited state characteristics of 44 modeled TCNQ-related molecules.
View Article and Find Full Text PDFJ Phys Chem Lett
August 2025
Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, P. R. China.
The practical applications of singlet fission (SF) are currently restricted by the limited number of SF-active materials and the stringent requirement of intermolecular interactions. It is still imperative but challenging work to develop an efficient SF system weakly dependent on molecular orientation and film morphology. Here, we elaborately designed a tethered cyclophane-like skeleton and constructed a disordered aggregation system.
View Article and Find Full Text PDFJ Phys Chem A
September 2025
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
Excimers are important excited-state homodimeric complexes affecting excited-state processes such as symmetry-breaking charge separation (SB-CS) and singlet fission (SF). Their formation is influenced by factors such as the solvent environment, spatial orientation, and distance between the chromophores. Our study uses MP2 and ADC(2) methods to explore excimer formation in a specific conformer of covalently linked azulene-fused anthracenes, out of two conformers, and .
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Department of Chemistry and Pharmacy, Profile Center FAU Solar, Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany.
Singlet fission (SF) is a spin-allowed photophysical process that generates two triplet excited states for one absorbed photon. It therefore has the potential to boost solar cell efficiencies beyond the 33% detailed balance limit. A better understanding of through-space and through-bond electronic coupling in SF, and their interplay, is essential for practical applications of SF materials.
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