High alcohol-soluble MoOx gel for interfacial layer in organic solar cells

Water-free solvent soluble, low-temperature processed metal oxides are important for preparing efficient and stable electronic devices, as well as the convenience in simplifying the device production process. Here we reported a facile approach with the features of low-temperature and solution-based process for the formation of a MoOx (s-MoOx) film as interface layer in polymer solar cells (PSCs). The absorbability, elementary composition, electronic property and surface microstructure of the s-MoOx are investigated in detail by ultraviolet-visible spectrophotometer (UV-vis), X-ray photoelectron spectrometry (XPS), ultraviolet photo-electron spectrometer (UPS) and atomic force microscopy (AFM). These investigations confirmed that such MoOx xerogel has high solubility in the organic alcohol solvents, such as ethanol and methanol. Meanwhile, this s-MoOx can be applied as the interfacial layer in organic solar cells via a low-temperature treatment (about 100 °C) due to its proper physical properties, and a power conversion efficiency (PCE) over 3% was achieved. In addition, the devices with s-MoOx shows excellent air-stability, and the PCE efficiency can maintain about 84% of its initial value after 100 h exposure in air, which is dramatically enhanced comparing with the common devices with PEDOT:PSS layer.