title: Electroluminescence from charge transfer states in polymer solar cells.
abstract: In this article we report the weak but omnipresent electroluminescence (EL) from several types of organic polymer:fullerene bulk heterojunction solar cells biased in the forward direction. The light emitted from blends of some commonly used polymers and the fullerene molecule is significantly different from that of any of the pure materials comprising the blend. The lower energy of the blend EL is found to correlate with both the voltage onset of emission and the open-circuit voltage of the photovoltaic cell under solar illumination. We accordingly interpret the emission to originate from interfacial charge transfer state recombination and emphasize EL as a very valuable tool to characterize the charge transfer state present in donor/acceptor organic photovoltaic (OPV) cells.
authors.affiliation: Biomolecular and Organic Electronics, Center of Organic Electronics, Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden. kritv@ifm.liu.se
authors.forename: Kristofer
authors.initials: K
authors.lastname: Tvingstedt
authors.forename: Koen
authors.initials: K
authors.lastname: Vandewal
authors.forename: Abay
authors.initials: A
authors.lastname: Gadisa
authors.forename: Fengling
authors.initials: F
authors.lastname: Zhang
authors.forename: Jean
authors.initials: J
authors.lastname: Manca
authors.forename: Olle
authors.initials: O
authors.lastname: Inganäs