title: Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor-Acceptor Conjugated Polymers.
abstract: Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wave functions, they often form semicrystalline thin films. In this work, we aim to understand whether distribution of crystallographic orientations affects exciton diffusion using a low-band-gap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer side chain can tune the dominant crystallographic orientation in the thin film, we have measured the quenching of polymer photoluminescence, and thus the extent of exciton dissociation, as a function of crystal orientation with respect to a quenching substrate. We find that the crystallite orientation distribution has little effect on the average exciton diffusion length. We suggest several possibilities for the lack of correlation between crystallographic texture and exciton transport in semicrystalline conjugated polymer films.
authors: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors: Alexander L
authors: AL
authors: Ayzner
authors: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Jianguo
authors: J
authors: Mei
authors: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Anthony
authors: A
authors: Appleton
authors: National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors: Dean
authors: D
authors: DeLongchamp
authors: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors: Alexandre
authors: A
authors: Nardes
authors: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Stephanie
authors: S
authors: Benight
authors: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors: Nikos
authors: N
authors: Kopidakis
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors: Michael F
authors: MF
authors: Toney
authors: Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Zhenan
authors: Z
authors: Bao
keywords: conjugated polymer; crystallographic orientation; exciton diffusion; fluorescence quenching; texture