© 2015 American Chemical Society. 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.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-C1-015-21
Acknowledgements: We thank the Bent group at Stanford University for help with ALD preparation of titania films. This work was partially supported by the Center for Advanced Molecular Photovoltaics, Award No. KUS-C1-015-21, made by King Abdullah University of Science and Technology. We also acknowledge support from the Global Climate and Energy Program at Stanford. GIXD measurements were carried out at the Stanford Synchrotron Radiation Lightsource, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. N.K. and A.M.N. acknowledge funding from the Energy Frontier Research Center “Molecularly Engineered Energy Materials (MEEMs)” funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract Number DE-SC0001342:001.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.