Controlling Exciton Diffusion and Fullerene Distribution in Photovoltaic Blends by Side Chain Modification.
The influence of crystallinity on exciton diffusion and fullerene distribution was investigated by blending amorphous and semicrystalline copolymers. We measured exciton diffusion and fluorescence quenching in such blends by dispersing fullerene molecules into them. We find that the diffusion length is more than two times higher in the semicrystalline copolymer than in the amorphous copolymer. We also find that fullerene preferentially mixes into disordered regions of the polymer film. This shows that relatively small differences in molecular structure are important for exciton diffusion and fullerene distribution.
†Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, United Kingdom.
Muhammad T
MT
Sajjad
†Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, United Kingdom.
Alexander J
AJ
Ward
‡Institute of Physics, Technische Universität Ilmenau, Langewiesener Straße 22, 98693 Ilmenau, Germany.|§Institute of Thermodynamics and Fluid Mechanics, Technische Universität Ilmenau, Helmholtzring 1, 98693 Ilmenau, Germany.
Christian
C
Kästner
†Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, United Kingdom.
Arvydas
A
Ruseckas
‡Institute of Physics, Technische Universität Ilmenau, Langewiesener Straße 22, 98693 Ilmenau, Germany.|∥Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosphenweg 7a, 07743 Jena, Germany.|⊥Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743 Jena, Germany.
Harald
H
Hoppe
†Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, United Kingdom.
Ifor D W
ID
Samuel
bulk heterojunction (BHJ); conjugated polymer; crystallinity; exciton diffusion length; organic solar cell