Orbital-resolved Observation of Singlet Fission
arXiv:2204.06824 · doi:10.1038/s41586-023-05814-1
Abstract
Singlet fission may boost photovoltaic efficiency [by transforming a singlet exciton into two triplet excitons and thereby doubling the number of excited charge carriers. The primary step of singlet fission is the ultrafast creation of the correlated triplet pair. While several mechanisms have been proposed to explain this step, none has emerged as a consensus. The challenge lies in tracking the transient excitonic states. Here we use time- and angle-resolved photoemission spectroscopy to observe the primary step of singlet fission in crystalline pentacene. Our results suggest a charge-transfer mediated mechanism with a hybridization of Frenkel and charge-transfer states in the lowest bright singlet exciton. We gained intimate knowledge about the localization and the orbital character of the exciton wave functions recorded in momentum maps. This allowed us to directly compare the localization of singlet and bitriplet excitons and decompose energetically overlapping states based on their orbital character. Orbital- and localization- resolved many-body dynamics promise deep insights into the mechanics governing molecular systems and topological materials.
arXiv comment24 pages, 4 main figures, 9 supplementary figures
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- Hybrid Frenkel-Wannier excitons facilitate ultrafast energy transfer at a 2D-organic interface
- Optimisation of ultrafast singlet fission in 1D rings towards unit efficiency
- A minimalist approach to 3D photoemission orbital tomography: algorithms and data requirements
- Coherent and incoherent excitation pathways in time-resolved photoemission orbital tomography of CuPc/Cu(001)-2O
- High-Order Harmonic Generation in Organic Molecular Crystals
- Observing the spatial and temporal evolution of exciton wave functions