Singlet fission (SF) is considered as a promising strategy to overcome the Shockley-Queisser limit of single-junction solar cells. However, only a handful of chromophores were observed to undergo SF to date. To broaden the number of SF chromophores, we designed a series of phosphorus-doped perylenes based on the diradical character strategy and examined their SF feasibility using theoretical calculations. By analysis of frontier orbitals, diradical character and aromaticity, SF-capable candidates were prescreened. These analyses reveal that the diradical character of perylene is effectively enhanced by P-doping at - and -positions of perylene, making SF more thermodynamically feasible. However, the diradical character remains nearly unchanged when P atoms are doped at -positions because the spin center cannot be stabilized, leading to a more endothermic SF. This study shows how SF-related energies and diradical character of SF chromophores are altered by P doping, and extends the SF-capable molecular library.
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http://dx.doi.org/10.1039/d4cp02048k | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Universität Rostock, Institut für Chemie, Albert-Einstein-Str. 3a, 18059, Rostock, GERMANY.
The linkage of an imidazole-based N-heterocyclic olefin (NHO), containing a terminal CH2 donor group, with a phosphorus-centered diradical molecular fragment leads to an open-shell singlet diphospha-indenylide system, a new class of P-heterocycles, which can be interpreted both as a phosphorus-centered diradicaloid and as a zwitterion with a permanent, overall charge separation between the N- and P-heterocyclic ring systems. The rotation of the imidazole ring, which is thermally possible due to a central C-C bond with a weakened π-component, changes both the charge separation and diradical character depending on the dihedral angle, as quantum mechanical calculations indicate. By varying the bulkiness of substituents at the imidazole-based NHO, it was possible to obtain different diphospha-indenylide species with different rotation angles in the solid state and hence varying diradical character.
View Article and Find Full Text PDFJ Comput Chem
January 2025
Department of Chemistry, Gottwald Center for the Sciences, University of Richmond, Richmond, Virginia, USA.
The energies and geometries of the lowest lying singlet and triplet states of the four diradicals formed by removing two H atoms from thiophene have been characterized. We utilized the highly correlated, multireference methods configuration interaction with single and double excitations with and without the Pople correction for size-extensivity (MR-CISD+Q and MR-CISD) and averaged quadratic coupled cluster theory (MR-AQCC). CAS (8,7) and CAS (10,8) active spaces involving σ, σ*, π, and π* orbitals were employed along with the cc-pVDZ and cc-pVTZ basis sets.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
School of Chemistry and Chemical Engineering, Inner Mongolia University, 235 West University Street, Hohhot, 010021, China.
Polycyclic aromatic hydrocarbons (PAHs) have attracted significant interest in material chemistry, particularly if they own extremely low band gaps and magnetic properties. However, challenges remain regarding the synthetic accessibility and energy saturation issues. In this study, we introduce NR-11, which consists of eleven aromatic rings in its main conjugation and is separately doped with two electron-rich nitrogen atoms.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, Málaga 29071, Spain.
Azuacenes, defined as azulene fused with acenes in a 6-7-5 ring topology and spanning lengths from 3 to 6 rings, have been synthesized using a new skeleton editing and [3 + 2] annulation synthesis protocol as a distinction regarding the procedures to obtain the 6-5-7 isomers. Comprehensive studies on ground-state and excited-state spectroscopy, electrochemical properties, chemical stability, and solid-state structure have been conducted to compare these azuacenes with acenes. For the same number of rings, we found that azuacenes improve the chemical stability of acenes (i.
View Article and Find Full Text PDFNat Commun
January 2025
School of Materials Science and Engineering, Hunan University of Science and Technology, Xiangtan, China.
[n]Peri-acenes ([n]PA) have attracted great interest as promising candidates for nanoelectronics and spintronics. However, the synthesis of large [n]PA (n > 4) is extremely challenging due to their intrinsic open-shell radical character and high reactivity. Herein, we report the successful synthesis and isolation of a derivative (1) of peri-hexacene in crystalline form.
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