Magnetic Characterization of Open-Shell Donor–Acceptor Conjugated Polymers

Document Type

Article

Publication Date

3-22-2022

School

Polymer Science and Engineering

Abstract

Donor–acceptor (DA) conjugated polymers (CPs) with narrow bandgaps and open-shell electronic structures offer a fundamentally new paradigm for integrating the spin degree of freedom within emerging functional devices. Recent advancements have demonstrated that control of long-range electronic correlations enables low-spin (S = 0) and high-spin (S = 1) DA CPs, in which extended π-conjugation overcomes the intrinsic instability of these electronic configurations in light-element materials. While design strategies that articulate mechanisms of spin alignment, topology control, and quantum mechanical exchange are emerging, dedicated studies of the magnetic behavior of these materials remain rare. Here, we utilize sensitive magnetometry techniques to analyze the magnetic properties of open-shell DA CPs with low- and high-spin ground states. We demonstrate improved measurement accuracy through combining vibrating sample magnetometry and superconducting quantum interference device magnetometry. This serves to overcome challenges associated with the inherently weak magnetic moments of these materials and a measurement environment in which the background signal is always significant and must be carefully removed. Analyzing the results following established models for paramagnetic materials enables precise quantification of the spin quantum number and temperature-dependent spin alignment. These studies articulate approaches that enable precise characterization of the bulk magnetic features of these heterogeneous and disordered materials systems, providing a path for rational property elucidation that will enable the integration of these materials within emerging technologies.

Publication Title

Journal of Physical Chemistry C

Volume

126

Issue

12

First Page

5701

Last Page

5710

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