We report a family of luminescent alternant diradicals which, at room temperature, support a ground-state spin-triplet, near-unity photoluminescence quantum yields, and optical spin addressability. These diradicals comprise trityl groups meta-linked via pyridyl or phenyl groups, enabling optically bright triplet-to-triplet and singlet-to-singlet transitions. At room temperature, we observe optically detected magnetic resonance in these systems at zero magnetic field and a strong magneto-photoluminescence (10% modulation at 2 mT applied magnetic field). Distinct photoluminescence bands (at 630 nm and 700 nm) show opposite-sign spin-optical responses, arising from spin-selective intersystem crossing between triplet and singlet manifolds. These bright, all-organic diradicals offer a new set of chemically tunable materials for room temperature spin-optical interfaces, paving the way for application as quantum sensors.
@article{arxiv.2510.09440,
title = {Room temperature optical control of spin states in organic diradicals},
author = {Rituparno Chowdhury and Alistair Inglis and Lucy E. Walker and Petri Murto and Chiara Delpiano-Cordeiro and Colin Morrison and Naitik A. Panjwani and Yao Fu and Yan Sun and Wei Zhou and Peter J. Skabara and Akshay Rao and Alexei Chepelianskii and Hugo Bronstein and Sam L. Bayliss and Richard H. Friend},
journal= {arXiv preprint arXiv:2510.09440},
year = {2025}
}