The Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor-Acceptor Conjugated Polymers

Published

December 30, 2015

Author(s)

Alexander L. Ayzner, Jianguo Mei, Anthony Appleton, Dean DeLongchamp, Alexandre Nardes, Stephanie Benight, Nikos Kopidakis, Michael F. Toney, Zhenan Bao

Abstract

Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wavefunctions, they often form semicrystalline thin films. Although it is known that the polymer crystal orientation plays a large role in determining the charge carrier mobility along a particular direction, little is known about how the relative crystal orientation affects diffusion of excitons in conjugated polymer thin films. In this work, we aim to address this question using a low-bandgap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer sidechain 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.

Citation

ACS Applied Materials and Interfaces

Pub Type

Journals

Keywords

organic photvoltaics, X-ray diffraction

Citation

Ayzner, A. , Mei, J. , Appleton, A. , DeLongchamp, D. , Nardes, A. , Benight, S. , Kopidakis, N. , Toney, M. and Bao, Z. (2015), The Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor-Acceptor Conjugated Polymers, ACS Applied Materials and Interfaces (Accessed October 8, 2024)