Magnetic Characterization of Open-Shell Donor-AcceptorConjugated Polymers br

Donor-acceptor (DA) conjugated polymers (CPs) with narrowbandgaps and open-shell electronic structures offer a fundamentally newparadigm for integrating the spin degree of freedom within emerging functionaldevices. Recent advancements have demonstrated that control of long-rangeelectronic correlations enables low-spin (S= 0) and high-spin (S= 1) DA CPs, inwhich extended pi-conjugation overcomes the intrinsic instability of theseelectronic configurations in light-element materials. While design strategies thatarticulate mechanisms of spin alignment, topology control, and quantummechanical exchange are emerging, dedicated studies of the magnetic behaviorof these materials remain rare. Here, we utilize sensitive magnetometry techniquesto analyze the magnetic properties of open-shell DA CPs with low- and high-spinground states. We demonstrate improved measurement accuracy through combining vibrating sample magnetometry andsuperconducting quantum interference device magnetometry. This serves to overcome challenges associated with the inherentlyweak magnetic moments of these materials and a measurement environment in which the background signal is always significant andmust be carefully removed. Analyzing the results following established models for paramagnetic materials enables precisequantification of the spin quantum number and temperature-dependent spin alignment. These studies articulate approaches thatenable precise characterization of the bulk magnetic features of these heterogeneous and disordered materials systems, providing apath for rational property elucidation that will enable the integration of these materials within emerging technologies.