Issue 9, 2021

Benzobisthiadiazole-based high-spin donor–acceptor conjugated polymers with localized spin distribution

Abstract

Stable organic semiconductors (OSCs) with a high-spin ground-state can profoundly impact emerging technologies such as organic magnetism, spintronics, and medical imaging. Over the last decade, there has been a significant effort to design π-conjugated materials with unpaired spin centers. Here, we report new donor–acceptor (D–A) conjugated polymers comprising cyclopentadithiophene and cyclopentadiselenophene donors with benzobisthiadiazole (BBT) and iso-BBT acceptors. Density functional theory calculations show that the BBT-based polymers display a decreasing singlet–triplet energy gap with increasing oligomer chain length, with degenerate singlet and triplet states for a N = 8 repeat unit. Furthermore, a considerable distance between the unpaired electrons with a pure diradical character disrupts the π-bond covalency and localizes the unpaired spins at the polymer ends. However, replacing the BBT acceptor with iso-BBT leads to a closed-shell configuration with a low-spin ground-state and a localized spin density on the polymer cores. This study shows the significance of the judicious choice of π-conjugated scaffolds in generating low- (S = 0) and high-spin (S = 1) ground-states in the neutral form, by modulation of spin topology in extended π-conjugated D–A polymers for emergent optoelectronic applications.

Graphical abstract: Benzobisthiadiazole-based high-spin donor–acceptor conjugated polymers with localized spin distribution

Supplementary files

Article information

Article type
Paper
Submitted
16 Feb 2021
Accepted
09 Mar 2021
First published
10 Mar 2021
This article is Open Access
Creative Commons BY-NC license

Mater. Adv., 2021,2, 2943-2955

Benzobisthiadiazole-based high-spin donor–acceptor conjugated polymers with localized spin distribution

M. A. Sabuj, M. M. Huda, C. S. Sarap and N. Rai, Mater. Adv., 2021, 2, 2943 DOI: 10.1039/D1MA00144B

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