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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.

We investigate anion–π binding modes in a cis-isomer of 3,5-dinitrophenyl-substituted calix[4]pyrrole with various anions via X-ray crystallographic analyses and compare its binding affinities with those of the corresponding trans-isomer. Sandwich-type anion–π interactions prove to not only enhancing anion binding abilities but also altering the anion-binding selectivity of the calix[4]pyrrole framework.