Reduced charge transfer exciton recombination in organic semiconductor heterojunctions by molecular doping.
We investigate the effect of molecular doping on the recombination of electrons and holes localized at conjugated-polymer-fullerene interfaces. We demonstrate that a low concentration of p-type dopant molecules (<4% weight) reduces the interfacial recombination via charge transfer excitons and results in a favored formation of separated carriers. This is observed by the ultrafast quenching of photoluminescence from charge transfer excitons and the increase in photoinduced polaron density by ~70%. The results are consistent with a reduced formation of emissive charge transfer excitons, induced by state filling of tail states.
Photonics and Optoelectronics Group, Department of Physics and CeNS, Ludwig-Maximilians-Universität München, 80799, Munich, Germany.
Felix
F
Deschler
Enrico
E
Da Como
Thomas
T
Limmer
Raphael
R
Tautz
Tillmann
T
Godde
Manfred
M
Bayer
Elizabeth
E
von Hauff
Seyfullah
S
Yilmaz
Sybille
S
Allard
Ullrich
U
Scherf
Jochen
J
Feldmann