Self-assembly of poly(2-vinylpyridine)-block-poly(ϵ-caprolactone) (P2VP-b-PCL) diblock copolymer in the presence of a selective solvent is investigated by transmission electron microscopy and atomic force microscopy. Addition of water into a P2VP-b-PCL solution in N,N-dimethylformamide at 20 °C produces elongated truncated lozenge shaped single crystals of uniform size and shape in large quantities. The single crystals are composed of PCL single-crystal layer sandwiched between two P2VP layers tethered on the top and bottom basal surfaces. The formation of the single crystals is found to depend on the temperature. These findings provide a facile approach to the preparation of uniform single crystals in large quantities.

We compare the impacts of tetracyanoborate and dicyanamide anions in solvent-free ionic liquid electrolytes upon the optoelectronic features of dye-sensitized solar cells based on an organic push-pull chromophore. With respect to dicyanamide, tetracyanoborate confers a bathochromic and higher photocurrent response upon a dye-coated mesoporous titania film. Numerical simulations on electrical impedance spectroscopies disclose that tetracyanoborate anions evoke a downward displacement of the conduction-band edge of an electrolytesinking nanocrystalline film in comparison with dicyanamide, generating a more favorable energy-offset at the titania/dye interface and therefore a better exciton dissociation yield, as proved via the transient emission measurements. An effective recombination reaction rate constant U 0k is used to depict the charge-transfer behavior at the titania/electrolyte interface in dye-sensitized solar cells. The negative impact of an about 4 times larger U 0k of the dicyanamide cell is overwhelmed by the noticeably higher conduction band edge, leading to the experimentally observed anion-dependent open-circuit photovoltage.