A transferable model for singlet-fission kinetics.

Autor: Yost SR; 1] Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA [2]., Lee J; 1] Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA [2]., Wilson MW; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., Wu T; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., McMahon DP; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., Parkhurst RR; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., Thompson NJ; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., Congreve DN; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., Rao A; Cavendish laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK., Johnson K; Cavendish laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK., Sfeir MY; Center for Functional Nanomaterials, Brookhaven National Laboratory, Building 735, Upton, New York 11973, USA., Bawendi MG; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., Swager TM; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., Friend RH; Cavendish laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK., Baldo MA; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA., Van Voorhis T; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachussetts 02139, USA.
Jazyk: angličtina
Zdroj: Nature chemistry [Nat Chem] 2014 Jun; Vol. 6 (6), pp. 492-7. Date of Electronic Publication: 2014 May 04.
DOI: 10.1038/nchem.1945
Abstrakt: Exciton fission is a process that occurs in certain organic materials whereby one singlet exciton splits into two independent triplets. In photovoltaic devices these two triplet excitons can each generate an electron, producing quantum yields per photon of >100% and potentially enabling single-junction power efficiencies above 40%. Here, we measure fission dynamics using ultrafast photoinduced absorption and present a first-principles expression that successfully reproduces the fission rate in materials with vastly different structures. Fission is non-adiabatic and Marcus-like in weakly interacting systems, becoming adiabatic and coupling-independent at larger interaction strengths. In neat films, we demonstrate fission yields near unity even when monomers are separated by >5 Å. For efficient solar cells, however, we show that fission must outcompete charge generation from the singlet exciton. This work lays the foundation for tailoring molecular properties like solubility and energy level alignment while maintaining the high fission yield required for photovoltaic applications.
Databáze: MEDLINE
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