Transparent All-Oxide Hybrid NiO:N/TiO2 Heterostructure for Optoelectronic Applications

Nickel oxide (NiO) is a p-type oxide and nitrogen is one of the dopants used for modifying its properties. Until now, nitrogen-doped NiO has shown inferior optical and electrical properties than those of pure NiO. In this work, we present nitrogen-doped NiO (NiO:N) thin films with enhanced properties compared to those of the undoped NiO thin film. The NiO:N films were grown at room temperature by sputtering using a plasma containing 50% Ar and 50% (O2 + N2) gases. The undoped NiO film was oxygen-rich, single-phase cubic NiO, having a transmittance of less than 20%. Upon doping with nitrogen, the films became more transparent (around 65%), had a wide direct band gap (up to 3.67 eV) and showed clear evidence of indirect band gap, 2.50–2.72 eV, depending on %(O2-N2) in plasma. The changes in the properties of the films such as structural disorder, energy band gap, Urbach states and resistivity were correlated with the incorporation of nitrogen in their structure. The optimum NiO:N film was used to form a diode with spin-coated, mesoporous on top of a compact, TiO2 film. The hybrid NiO:N/TiO2 heterojunction was transparent showing good output characteristics, as deduced using both I-V and Cheung’s methods, which were further improved upon thermal treatment. Transparent NiO:N films can be realized for all-oxide flexible optoelectronic devices.

Sensibilization of p-NiO with ZnSe/CdS and CdS/ZnSe quantum dots for photoelectrochemical water reduction

Pairing ZnSe/CdS and CdS/ZnSe core/shell quantum dots with NiO thin film photocathodes enhances the photoelectrochemical water reduction.

Study the Effect of Cu Doping on Optical and Structural Properties of NiO Thin Films

In this work, copper doped nickel oxide as the thin films have been elaborated by a spin coating method, the nickel chloride hexahydrate (0.8M) and copper (II) chloride dehydrate (Cu/Ni = 0, 2.15, 4.3, 8.6 and 12.9 At.%) were used to prepare the Cu doped NiO thin films. The Cu doped NiO thin films were heated at a crystallization temperature of 600 °C with 2 h. The obtained thin films by spin coater method have a film thickness in the order of 400 nm. The prepared Cu doped NiO thin films have a polycrystalline with cubic structure (200) peak was observed. The optical property shows that the prepared thin films have a transmittance of about 70 %. The Cu doped NiO thin films have minimum bandgap energy is 3.85 eV at 12.9 at.%, the thin film deposited at 8.6 at.% has the highest value of Urbach energy is 425 meV. The Cu doped NiO thin films have a high electrical conductivity of 8.6 at% it is 7 (Ω.cm)−1. The prepared Cu doped NiO thin film was suitable for gas sensing applications due to the existing phase and higher electrical conductivity.

Effect of Sputtering Power on Optical Properties of Nickel Oxide Electrochromic Thin Films

The preparation and characterization of nickel oxide (NiO) thin film for electrochromic smart window applications are studied. The NiO thin film was prepared by the DC magnetron sputtering from a pure nickel target. The sputtering power was varies in the interval 50–200 W. The crystallinity and physical morphology of NiO films are characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. The XRD result revealed that polycrystalline NiO thin films with preferred growth directions along (111) and (200) planes are obtained. Moreover, the electrochromic property of NiO thin films was investigated with a UV-Visible spectrophotometer. The colored state of the electrochromic cell was obtained by the ion insertion at the 1-V external applied bias in 0.1 M KOH. The reversibility between the colored and bleached states is confirmed by the optical transmittance. The result shows the optical contrast as high as 28.68.

Synthesis and Characterization of Physical Properties of the NiO Thin Films by Various Concentrations

In this work, nickel oxide was deposited on a glass substrate at by spray deposition technique; the structural, optical and electrical properties were studied at different NiO concentrations (0.05, 0.10 and 0.15 mol.l−1). Polycrystalline NiO films with a cubic structure with a strong (111) preferred orientation were observed at all sprayed films with minimum crystallite size of 11.97 nm was attained of deposited film at 0.1 mol.l−1. However, α-Ni(OH)2 was observed at 0.15 mol.l−1. The NiO thin films have good transparency in the visible region, the band gap energy varies from 3.54 to 376 eV was affected by NiO concentration, it is shown that the NiO thin film prepared at 0.05 mol.l−1 has less disorder with few defects. The NiO film deposited at 0.15 mol.l−1 has the electrical conductivity was 0.169 (Ω.cm)−1.