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Spin-dependent recombination probed through the dielectric polarizability.


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Authors

Bayliss, Sam L 
Greenham, Neil C 
Friend, Richard H 
Bouchiat, Hélène 
Chepelianskii, Alexei D 

Abstract

Despite residing in an energetically and structurally disordered landscape, the spin degree of freedom remains a robust quantity in organic semiconductor materials due to the weak coupling of spin and orbital states. This enforces spin-selectivity in recombination processes which plays a crucial role in optoelectronic devices, for example, in the spin-dependent recombination of weakly bound electron-hole pairs, or charge-transfer states, which form in a photovoltaic blend. Here, we implement a detection scheme to probe the spin-selective recombination of these states through changes in their dielectric polarizability under magnetic resonance. Using this technique, we access a regime in which the usual mixing of spin-singlet and spin-triplet states due to hyperfine fields is suppressed by microwave driving. We present a quantitative model for this behaviour which allows us to estimate the spin-dependent recombination rate, and draw parallels with the Majorana-Brossel resonances observed in atomic physics experiments.

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Keywords

0912 Materials Engineering

Journal Title

Nat Commun

Conference Name

Journal ISSN

2041-1723
2041-1723

Volume Title

6

Publisher

Springer Science and Business Media LLC
Sponsorship
Engineering and Physical Sciences Research Council (EP/M005143/1)
Engineering and Physical Sciences Research Council (EP/G060738/1)
This work was supported by the Engineering and Physical Sciences Research Council [Grants No. EP/G060738/1]. A. D. C. acknowledges support from the E. Oppenheimer Foundation and St Catharine's College, Cambridge. S. L. B. is grateful for support from the EPSRC Supergen SuperSolar Project, the Armourers and Brasiers Gauntlet Trust and Magdalene College, Cambridge.