In this paper, we report on the effect of titanium dioxide (TiO2) target sintering temperature on the morphological and optical properties of amorphous titanium dioxide thin films synthesized by pulsed laser deposition (PLD) on indium tin oxide (ITO) glass substrate and subsequently heat-treated in air at low temperature (150 °C). Three types of targets were used, unsintered (pressed at room temperature), sintered at 500 °C and sintered at 1000 °C. The surface morphology of the samples was investigated by scanning electron microscopy (SEM), and profilometry was used for thickness measurements. The structural properties of the films were examined by X-ray diffraction (XRD), while their optical properties were studied by UV‒vis spectroscopy. The obtained TiO2 thin films have an amorphous nature, as shown by XRD analysis. Profilometer showed that sintered target samples have more reliable thicknesses than unsintered ones. The SEM studies revealed the sufficient structural homogeneity of sintered target nanosized TiO2 films and agglomerates in the case of unsintered target film. The UV‒vis transmittance spectra showed high transparency in the visible range of PLD films, proportional to the target sintering temperature. The optical band gaps of the films deposited using the 500 °C and 1000 °C sintered targets are closer to those of anatase and rutile phases, respectively, which provides a promising approach to the challenges of amorphous TiO2-based nanostructures.

The Market for photovoltaic cells (PV) has grown fast due to a higher demand on PV applications. However, there are still the transport and connection problems of the PV systems to the grid because of the difference in the current form. To assure the adequate connection between the PV sources and the network, the conversion of direct current (DC) to an alternative current (AC) is required and provided by an electronic device known as the inverter. In this last years, the conventional inverter structure reached its limits in power level and conversion performance. The multilevel inverter (MLI) structure was introduced and widely used in high power and high voltage applications to solve the conventional inverter limitation problem. In this paper, the Neutral-Point-Clamped (NPC) topology of the MLI was simulated to evaluate the effect of modulation index variation of the control technique on the harmonic behavior of the fifteen-level NPC. The simulation results were useful for the optimization of the MLI control technique toward the decrease of the harmonic (THD) effect on the NPC MLI. Keyword:Multilevel INTRODUCTIONPhotovoltaic (PV) systems world market know a fast growth during the last year due to the necessity of developing the renewable energy to replace the fossil fuels [1]. However, this rapid growth required in parallel the improvement of the PV chain efficiency such as the PV generator energy yielding, the electrical power transport performance and the adequate connection to the grid [2]. One of the important parts of the conversion chain devices is the inverter which allows the conversion of DC signal to AC signal in purpose to permit the distribution and connection of the output electrical energy of the PV generator to the network [3]. In addition to PV conversion chain, inverters are used in power system applications and uninterrupted power supplies industries [4]. The inverters power efficiency to feed the different type of loads of the grid reach the max level and it is due to the increase of inductive load usage. More inductive loads mean more harmonics and less conversion efficiency [5]. Improvement of the output power quality of the inverter required reducing its total harmonic distortion (THD) content and decrease the size of the filter used [6]. As a solution for this requirement, a new family of the inverter has emerged and known as the multilevel inverter [7]. Multilevel Inverter (MLI) technology assures some advantages comparably to the conventional technology and deals with higher power applications which make it much easier to deal with lower power applications such as the PV systems [8][9][10][11][12][13][14][15][16][17][18][19]. One of the main advantages of the MLI structure is the improvement of the output voltage waveform by approaching the sinusoidal waveform which implicates reducing the harmonic stress

TiO2–SiO2 nanocomposite thin films have gained the attention of the scientific community due to their unique physical and chemical properties. In this paper, we report on the fabrication and characterization of a TiO2–SiO2 nanocomposite disk-shaped target. The target was used for the deposition of TiO2–SiO2 nanocomposite thin films on fluorine-doped tin oxide/glass substrates using the pulsed laser deposition (PLD) technique. The thicknesses of the thin films were fixed to 100 nm, and the deposition temperature ranged from room temperature to 300 °C. As revealed by the microstructural and morphological characterizations revealed, the TiO2–SiO2 nanocomposite thin films are amorphous and display homogeneous distribution. The determined values of the indirect optical band gap range from 2.92 to 3.07 eV, while those of the direct optical band gap lie between 3.50 and 3.55 eV. Additionally, as the deposition temperature decreases, the light transmission increases in the visible and in the ultraviolet ranges, which is suitable for flexible perovskite solar cells. This research can uncover new insights into the fabrication of amorphous TiO2–SiO2-based nanostructured thin films using the PLD technique for perovskite solar cell technology.