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High-spin ground-state organic materials with unique spin topology can significantly impact molecular magnetism, spintronics, and quantum computing devices. However, strategies to control the spin topology and alignment of the unpaired spins in different molecular orbitals are not well understood. Here, we report modulating spin distribution along the molecular backbone in high-spin ground-state donor–acceptor (D–A) conjugated polymers. Density functional theory calculations indicate that substitution of different heteroatoms (such as C, Si, N, and Se) alters the aromatic character in the thiadiazole unit of the benzobisthiadiazole (BBT) acceptor and modulates the oligomer length to result in high-spin triplet ground-state, orbital and spin topology. The C, Si, and Se atom substituted polymers show a localized spin density at the two opposite ends of the polymers. However, a delocalized spin distribution is observed in the N substituted polymer. We find that the hybridization (sp 3 vs. sp 2 ) of the substituent atom plays an important role in controlling the electronic structure of these materials. This study shows that atomistic engineering is an efficient technique to tune the spin topologies and electronic configurations in the high-spin ground-state donor–acceptor conjugated polymers, compelling synthetic targets for room-temperature magnetic materials.
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This content will become publicly available on June 6, 2026
Ground-State Charge-Transfer Doping Interactions in Donor–Acceptor Semiconducting Polymers
Conjugated polymers are at the heart of numerous current and emerging technologies. Doping, a process by which charge carriers are introduced, is crucial to their functionality and performance. Despite significant historical context and the exploration of a broad chemical space, doping processes that are activated by formation of a ground-state charge-transfer complex (GS-CTC), which is mediated by the supramolecular hybridization between the frontier molecular orbitals of distinct molecular species, remain poorly understood. There are no clear demonstrations of this phenomena in contemporary donor–acceptor (DA) conjugated polymers (CP). Here, using diketopyrrolopyrrole-based donor–acceptor semiconducting polymers and a -conjugated penta-t-butylpentacyanopentabenzo[25]annulene “cyanostar” macrocycle, we demonstrate the first examples of features that control GS-CTC formation in contemporary DA CP frameworks. Using complementary experimental techniques and theory, we articulate how subtle molecular, electronic, and solid-state features impact supramolecular hybridization of the frontier molecular orbitals and impact the resultant (opto)electronic, magnetic, and transport properties. These studies demonstrate that subtle effects arising from the admixture between distinct -conjugated materials can have dramatic outcomes on properties and performance through modification of the density of states (DOS). These results will enable completely new design rules for organic semiconductors with precise property control.
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- PAR ID:
- 10609399
- Publisher / Repository:
- ChemRxiv
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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