Fabrication And Characterization Of CdO2 Nanoparticles For Solar Cells Applications

In this study, CdO2 thin films, which was prepared by chemical method and deposited by drop casting technique on glass and silicon substrates have been studied . The structural, optical and chemical analysis were investigated. X-ray diffraction (XRD) measurements reveal that the CdO2 thin film was polycrystalline, cubic structure and there is no trace of the other material. UV-Vis measurements assure that the energy gap of CdO2 thin film was found to be 2.5eV. I-V characterization of the solar cell under illumination at 40mW/cm2 fluence was investigated . The open circuit voltage (Voc) was 4.7V and short-circuit current density (Isc) was 0.38 mA . These measurements show that the fill factor (FF) and the conversion efficiency (η) ,were 29.4% and 1.66% respectively. Keywords—CdO2 , Thin film, XRD, Energy gap, Drop casting , Solar cells, AFM 1Introduction Cadmium oxide is transparent conducting oxides (TCOs) materials that hold both high electrical conductivity and high optical transparency (>80%) in the visible light region of the electromagnetic spectrum [1]. CdO is a n-type semiconductor with nearly metallic conductivity [2]. It has a direct energy band gap (Eg) of ~2.3 eV and two indirect transitions at lower energies [3]. CdO has extensive of applications as solar cells, windows, flat panel display, photo transistors. It was experimentally proven that structural, electrical and optical properties are very sensitive to the film structure and deposition conditions [4,5]. Such transparent conductors are being used comprehen-sively in thin film solar cells [6] and optoelectronic devices [7]. CdO films can be synthesized by many techniques such as sputtering [8], chemical vapor deposition (CVD) [9], spray pyrolysis [10], thermal evaporation [11] sol gel [12], and chemical bath deposition [13] Among various methods, spray pyrolysis is one through which the films can be coated for large area. In this work, the structural and optical properties of CdO2 thin films deposited on glass and silicon wafer are prepared in order to estimate some physical properties of this metal oxides. According to our knowledge this is the first trial to examine the use of CdO2 prepared by a simple chemical method for solar cell applications. 2Materials and Methodology In a typical procedure, 1.5g of Cd(NO3)2.H2O ,(BDH Chemicals Ltd Pool England) was dissolved in 50 ml of PVC (Sigma Aldrich USA) 1WT%. and ethanol (99.9%)was used throughout the experiment. The solution was put into a round-bottom flask with stirring. The color of the mixture was transparent. 25ml of NaOH (1M) was rapidly added to the mixture, and a nanopowder suspension was formed as shown in figure 1.The suspension was kept at 75°C for 1h. After cooling at room temperature, the particles were separated by centrifugation and were washed with ethanol to remove any contaminations. Fig. 1. CdO2 freshly colloidal nanoparticles dissolved in PVC. Journal of Multidisciplinary Engineering Science and Technology (JMEST) ISSN: 2458-9403 Vol. 3 Issue 8, August 2016 www.jmest. org JMESTN42351732 5428 X-ray diffractometer (XRD-6000, Shimadzu) was used to investigate the structure and crystallinity of nanoparticles. The absorption of the colloidal nanoparticles solution was measured by using UV–Vis (UV -1800, Shimadzu, Japan) 3Results and discussion The XRD diffraction patterns of synthesized CdO2 nanoparticles films prepared by quick chemical method were shown in Figure 2. Two peaks at 2θ = 29.53 ◦ and 48.04 ◦ corresponds to (111) and (220) planes were observed respectively ,which belong to CdO2 cubic structure (JCPDS card no.039-1221), The crystallite size (D) was calculated by using Scheerer’s formula [14]. D = 0.94 λ  cos θ (1) Where λ is the x-ray wavelength of CuKα source (λ= 0.154056 nm), θ is the Braggs angle and β is the full width at half maximum (FWHM) of the diffraction peak in radians. The dislocation density ( ) and microstrain () values are calculated by using the following relations [15].