Thermal oxidation fabrication of NiO film for optoelectronic devices

•A novel thermal oxidation strategy to fabricate NiO efficient HTLs for optoelectronic devices.•The as-prepared NiO film is bunsenite structure composed of uniform NiO.•The devices exhibit higher PCE in ambient conditions than devices based on PEDOT:PSS HTLs. In this work, NiO coating was fabricated by magnetron sputtering method on quartz and indium tin oxide (ITO) substrates in an inert gas ambient of Ar followed by a thermal oxidation process in air at 400°C for 2h. The NiO coating was analyzed by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and UV–vis spectrometer. A preliminary photovoltaic performance measurement of the as-prepared device (ITO/NiO/poly-TPD/PC71BM/Al) shows a short circuit current density (Jsc) of 5.6mAcm−2 and power conversion efficiency (PCE) of 1.5% under an illumination of 100mWcm−2. The PCE of device with NiO HTLs was ca. 20% higher than those of the devices based on PEDOT:PSS hole transport layers (HTLs). The thermal oxidation fabricated NiO coating may provide an excellent route to fabricate other NiO-based optoelectronic devices.