Publications associated with Advanced Functional Materials and Devices Group

Experimental and theoretical study of phase separation in ZnPc:C60 blends

Organic Electronics: physics, materials, applications 27 (2015) 183-191

T Mönch, TS Sherkar, LJ Anton Koster, P Friederich, M Riede, P Formanek, C Koerner, K Vandewal, W Wenzel, K Leo

© 2015 Published by Elsevier B.V.Understanding the relationship between the absorber layer microstructure and the power conversion efficiency is of paramount importance to further improve the efficiency of organic solar cells. Utilizing transmission electron microscopy (TEM), (photo-)conductive atomic force microscopy ((p)cAFM), 3D drift-diffusion simulations, and density functional theory, we reveal the microscopic origins of phase-separation in a blend of zinc phthalocyanine (ZnPc) and C<inf>60</inf>, used as an absorber layer in organic solar cells. By means of (p)cAFM, we observe photoconductive, circular structures at the surface, which are identified as α-ZnPc islands. Moreover, in agreement with TEM investigations, we observe photoconductive, nanorod-like structures close to the surface which we assign to β-ZnPc. Finally, we apply a 3D drift-diffusion simulation based on the morphology determined by TEM to provide a link between the different contrasts observed in pcAFM and TEM.

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