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Efficient charge generation by relaxed charge-transfer states at organic interfaces.

Authors :
Vandewal, Koen
Albrecht, Steve
Hoke, Eric T.
Graham, Kenneth R.
Widmer, Johannes
Douglas, Jessica D.
Schubert, Marcel
Mateker, William R.
Bloking, Jason T.
Burkhard, George F.
Sellinger, Alan
Fréchet, Jean M. J.
Amassian, Aram
Riede, Moritz K.
McGehee, Michael D.
Neher, Dieter
Salleo, Alberto
Source :
Nature Materials; Jan2014, Vol. 13 Issue 1, p63-68, 6p
Publication Year :
2014

Abstract

Interfaces between organic electron-donating (D) and electron-accepting (A) materials have the ability to generate charge carriers on illumination. Efficient organic solar cells require a high yield for this process, combined with a minimum of energy losses. Here, we investigate the role of the lowest energy emissive interfacial charge-transfer state (CT<subscript>1</subscript>) in the charge generation process. We measure the quantum yield and the electric field dependence of charge generation on excitation of the charge-transfer (CT) state manifold via weakly allowed, low-energy optical transitions. For a wide range of photovoltaic devices based on polymer:fullerene, small-molecule:C<subscript>60</subscript> and polymer:polymer blends, our study reveals that the internal quantum efficiency (IQE) is essentially independent of whether or not D, A or CT states with an energy higher than that of CT<subscript>1</subscript> are excited. The best materials systems show an IQE higher than 90% without the need for excess electronic or vibrational energy. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
14761122
Volume :
13
Issue :
1
Database :
Complementary Index
Journal :
Nature Materials
Publication Type :
Academic Journal
Accession number :
93302978
Full Text :
https://doi.org/10.1038/nmat3807