Reinvestigation of the Magneto-Optical Properties of Polythiophenes

From optical isolation to magnetic field detection and imaging, magneto-optic devices have become an integral part of our lives. While these technologies traditionally rely on expensive, inorganic substances with limited versatility for device architectures, a new generation of organic semiconducting polymers is being evaluated as a promising substitute. The magneto-optic activity of materials is determined by their performance in a phenomenon known as Faraday rotation, where linearly polarized light rotates as it passes through a transparent medium in the presence of an external magnetic field. Polythiophenes, a class of common organic materials, have been reported to exhibit exceptional magneto-optical properties, surpassing the performance of traditional inorganic materials; however, this study shows that the reported results were irreproducible. We propose that the observed discrepancy is linked with the degree of regioregularity of the polymer and offer a mechanistic explanation of the origin of polymer errors, uncovering an important structure-activity trend in organic magneto-optic materials. This work aims to shed light on the general principles for enhancing the magneto-optical performance of organic materials, paving the way for their broader application in novel technologies.