Abstract
We study the surface and interfacial morphology of a bulk heterojunction (BHJ) layer with the solvent additive effect by using the X-ray reflectivity and the grazing incidence X-ray scattering techniques. The BHJ layer consists of poly(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophene-4,6-diyl) (PTB7) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) deposited on a poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) coated Si substrate. An interfacial layer with a low electron density is observed between the BHJ and PEDOT:PSS layers, which becomes less distinct when the additive 1,8-diiodooctane (DIO) is added to the film processing solvent. This result indicates that DIO causes PC71BM to become more uniformly distributed throughout the entire BHJ layer. The surface roughness of the BHJ significantly decreases with increasing addition of DIO. The understanding of the surface and interfacial morphology gives an important clue to improving the structures and efficiency.
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Acknowledgments
This research was supported by the National Research Foundation of Korea (NRF) (NRF-2014R1A2A1A1005 2454 and 2015R1A5A1009962).
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Kim, A., Lee, J., Carnis, J. et al. Surface and Interfacial Morphology of Bulk Heterojunction Layers in Organic Solar Cells with Solvent Additive. J. Korean Phys. Soc. 75, 498–502 (2019). https://doi.org/10.3938/jkps.75.498
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DOI: https://doi.org/10.3938/jkps.75.498