Year: 2026
Type: article
Abstract: Singlet fission and triplet-triplet annihilation (TTA) are spin-dependent phenomena critical to optoelectronics. The dynamics of spin populations during geminate triplet pair separation are crucial for controlling fission and TTA rates. We show that the Dzyaloshinskii-Moriya interaction (DMI) induces level crossings between spin manifolds, affecting spin populations and TTA rates in crystalline fission semiconductors. By investigating spin-dependent fluorescence in a triplet exciton pair with the magnetic field aligned along the fine structure tensor, we isolate the effect of DMI, as the triplet wave functions remain unaffected by the field. Our results reveal that DMI introduces additional TTA pathways that are forbidden by spin conservation, explaining the observed evolution of optically detected magnetic resonance signals with varying magnetic field. The magnitude of the DMI interactions needed to reproduce the experimental data is further confirmed by highly correlated wave function-based ab initio calculations. This Letter highlights the significant impact of DMI on the optical properties of triplet excitons, advancing our understanding of spin dynamics in these systems.
Source: Physical Review Letters
DOI: 10.1103/7mt2-968k
Authors: Yan Sun, G. Ricci, M. Monteverde, V. Derkach, T. Chanelière, E. Aldridge, D. Casanova, D. Beljonne, J. E. Anthony, A. D. Chepelianskii
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: Donostia International Physics Center, Ministerio de Ciencia, Innovación y Universidades, Waalse Gewest, European Commission, Agence Nationale de la Recherche, Fonds De La Recherche Scientifique - FNRS, Centre National de la Recherche Scientifique, Horizon 2020 Framework Programme, European Research Council, Agencia Estatal de Investigación, European Social Fund
OpenAlex ID: W7138366200