RESUMO
We demonstrate hybrid organic photovoltaic (HOPV) bilayer devices with very high open circuit voltages (VOC) of 1.18 V based on a sol-gel processed zinc oxide (ZnO) acceptor and a vacuum deposited boron subphthalocyanine chloride (SubPc) donor layer. X-ray photoelectron spectroscopy (XPS) and Kelvin Probe (KP) measurements of the ZnO/SubPc interface show that the ZnO preparation conditions have a significant impact on the film composition and the electronic properties of the interface, in particular the work function and interface gap energy. Low temperature processing at 120 °C resulted in a ZnO work function of 3.20 eV and the highest VOC of 1.18 V, a consequence of the increased interface gap energy.
RESUMO
Waterborne polymer films made from soft polymer latex dispersions generally suffer from deterioration of chemical resistance and physical barrier properties under high humidity conditions and upon solvent exposure. Here we demonstrate the fabrication of robust polyhedral cellular polymer films from poly(methyl methacrylate-co-butyl acrylate) latexes, which were made by emulsion polymerization using a 2-ureido-4-pyrimidinone (UPy) functional methacrylate comonomer. Multiple hydrogen bond (MHB) arrays provided by UPy groups arrest the film formation process thereby creating a cellular reinforcement. The cellular polymer films exhibit impressive physical and mechanical properties. Upon solvent exposure, the films show colloidal crystalline-type Bragg diffraction features and do not suffer excessive and deteriorative uptake of water and, more remarkably, can absorb high amounts of organic solvents, thereby turning into an organogel with preservation of shape, up to a 14-fold volumetric swelling ratio of the polymer films in case of chloroform.
