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