A High-Spin Ground-State Donor-Acceptor Conjugated Polymer

A.E. London, University of Southern Mississippi
H. Chen, University of Alabama
M.A. Sabuj, Mississippi State University
J. Tropp, University of Southern Mississippi
M. Saghayezhian, Louisiana State University
N. Eedugurala, University of Southern Mississippi
B.A. Zhang, University of Southern Mississippi
Y. Liu, Lawrence Berkeley National Laboratory
X. Gu, University of Southern Mississippi
B.M. Wong, University of California, Riverside
N. Rai, Mississippi State University
M.K. Bowman, University of Alabama
J.D. Azoulay, University of Southern Mississippi

Abstract

Interest in high-spin organic materials is driven by opportunities to enable far-reaching fundamental science and develop technologies that integrate light element spin, magnetic, and quantum functionalities. Although extensively studied, the intrinsic instability of these materials complicates synthesis and precludes an understanding of how fundamental properties associated with the nature of the chemical bond and electron pairing in organic materials systems manifest in practical applications. Here, we demonstrate a conjugated polymer semiconductor, based on alternating cyclopentadithiophene and thiadiazoloquinoxaline units, that is a ground-state triplet in its neutral form. Electron paramagnetic resonance and magnetic susceptibility measurements are consistent with a high-to-low spin energy gap of 9.30 × 10⁻³ kcal mol⁻¹. The strongly correlated electronic structure, very narrow bandgap, intramolecular ferromagnetic coupling, high electrical conductivity, solution processability, and robust stability open access to a broad variety of technologically relevant applications once thought of as beyond the current scope of organic semiconductors.