A team of 13 investigators implemented an entirely new macromolecular design paradigm such that a low bandgap organic semiconducting polymer was synthesized in order to yield a material that is a ground state triplet (high-spin) in its neutral form. While predicted by Hund’s rule, such a material has eluded synthesis until now.
These studies are the first of their kind that overcome significant and historically rooted challenges associated with high-spin organic materials and open access to a broad variety of technologically relevant applications thought of as beyond the current scope of functional organic materials systems.
Organic semiconductors have witnessed a dramatic increase in recent decades, with impressive demonstrations of new functionality, devices, and commercial applications, largely based on donor- acceptor conjugated polymers. High spin configurations bring new notions of spin manipulation, organic magnetism, quantum functionalities and interrelated optoelectronic properties at the forefront of research efforts in diverse fields such as chemistry, materials science, and condensed matter physics. Although extensively studied, the intrinsic instability of this electronic configuration in light-element (carbon- based) materials complicates synthesis and precludes an understanding of how some of the most fundamental properties associated with the nature of the chemical bond (electron pairing) in organic materials systems manifest in practical applications.
To this end, the authors have implemented an entirely new macromolecular design paradigm, so that strong electron correlations give rise to: i) the narrowest bandgap achieved in a solution-processable conjugated polymer; ii) the first demonstration of intramolecular ferromagnetic coupling in a mid-scale molecular system; and iii) the first example of a ground-state triplet stabilized through extensive delocalization in a donor-acceptor structure. This study is the first of its kind that overcomes significant and historically rooted challenges associated with high spin organic materials and opens access to a broad variety of technologically relevant applications thought of as beyond the current scope of organic semiconductors and functional organic materials systems.
The design guidelines disclosed in this paper will not only be the basis for a new generation of materials with more complex and tunable electronic structures, emergent functionalities and new devices, but will also serve as a platform for fundamental investigations of chemical bonding and electron pairing in organic materials systems. We believe this paper will be recognized as one of the pioneering efforts in this area.