Fullerene-Free Polymer Solar Cells with Highly Reduced Bimolecular Recombination and Field-Independent Charge Carrier Generation.
Photogeneration, recombination, and transport of free charge carriers in all-polymer bulk heterojunction solar cells incorporating poly(3-hexylthiophene) (P3HT) as donor and poly([N,N'-bis(2-octyldodecyl)-naphthelene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)) (P(NDI2OD-T2)) as acceptor polymer have been investigated by the use of time delayed collection field (TDCF) and time-of-flight (TOF) measurements. Depending on the preparation procedure used to dry the active layers, these solar cells comprise high fill factors (FFs) of up to 67%. A strongly reduced bimolecular recombination (BMR), as well as a field-independent free charge carrier generation are observed, features that are common to high performance fullerene-based solar cells. Resonant soft X-ray measurements (R-SoXS) and photoluminescence quenching experiments (PQE) reveal that the BMR is related to domain purity. Our results elucidate the similarities of this polymeric acceptor with the superior recombination properties of fullerene acceptors.
†Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany.
Steffen
S
Roland
†Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany.
Marcel
M
Schubert
‡Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, United States.|§National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States.
Brian A
BA
Collins
†Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany.
Jona
J
Kurpiers
∥Polyera Corporation, Skokie, Illinois 60077, United States.
Zhihua
Z
Chen
∥Polyera Corporation, Skokie, Illinois 60077, United States.
Antonio
A
Facchetti
‡Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, United States.
Harald
H
Ade
†Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany.
Dieter
D
Neher
all-polymer solar cells; bimolecular recombination; domain purity; organic solar cells; photocurrent generation; reduced recombination