We report a method of fabricating a high work function, solution processable vanadium oxide (V₂O_x(sol)) hole-extracting layer. The atmospheric processing conditions of film preparation have a critical influence on the electronic structure and stoichiometry of the V₂O_x(sol), with a direct impact on organic photovoltaic (OPV) cell performance. Combined Kelvin probe (KP) and ultraviolet photoemission spectroscopy (UPS) measurements reveal a high work function, n-type character for the thin films, analogous to previously reported thermally evaporated transition metal oxides. Additional states within the band gap of V₂O_x(sol) are observed in the UPS spectra and are demonstrated using X-ray photoelectron spectroscopy (XPS) to be due to the substoichiometric nature of V₂O_x(sol). The optimized V₂O_x(sol) layer performance is compared directly to bare indium–tin oxide (ITO), poly(ethyleneoxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and thermally evaporated molybdenum oxide (MoO_x) interfaces in both small molecule/fullerene and polymer/fullerene structures. OPV cells incorporating V₂O_x(sol) are reported to achieve favorable initial cell performance and cell stability attributes.

We report increased cell performance for boron subphthalocyanine chloride (SubPc)/fullerene (C₆₀) organic photovoltaic (OPV) cells when thermally evaporated vanadium oxide (V₂O_X) thin films are incorporated as a hole-extracting layer at the indium-tin oxide (ITO)/SubPc interface. Ultra-violet photoemission spectroscopy (UPS) studies of the V₂O_X films reveal highly n-type character, with a large work function of 6.8 eV. This correlates well with recently reported data for other metal oxide hole-extracting layers, such as molybdenum oxide and tungsten oxide, in contrast to the p-type character previously reported for V₂O_X films. There is significant improvement in energy level alignment for hole-extraction when cells utilise the V₂O_X layer at the ITO/SubPc interface, resulting in substantial increases in open circuit voltage (V_OC) and power conversion efficiency (η_p).

A combined quantitative experimental and theoretical structure determination shows TCNQ is not bent on Ag(111) as expected from conventional wisdom.

Non-spherical particles have the potential to adopt multiple orientations once adhered to a liquid–liquid interface. In this work we combine simulations and experiments to investigate the behaviour of an isolated microscopic hematite particle of superellipsoidal shape. We show that this microparticle can adopt one of three orientations when adhered to a hexadecane–water interface. Two of the orientations, and estimates for their relative populations, could be assigned to two thermodynamic minima on the energy landscape as generated through both free-energy minimization and particle trajectory simulations. The third orientation was found to correspond to a kinetically trapped state, existing on certain particle trajectories in a region of a negligible gradient in free energy. To underpin the simulations the individual orientation of a set of 100 isolated particles was explored by means of scanning electron microscopy (SEM) using the gel trapping technique as a tool. Atomic force microscopy (AFM) was additionally used to support the experimental findings. This is the first example of such a kinetic metastable state being observed for particles at liquid–liquid interfaces.