Effect of Annealing on Copper Oxide Thin Films and Its Application in Solar Cells

Abstract

Cupric Oxide (CuO) thin films were prepared by chemical spray pyrolysis (CSP) method at 400°C on glass and p-type Si substrate and then the films were annealed at 500°C and 600°C. The structural, optical and electrical properties of the thin films are measured. The analysis of X-ray diffraction (XRD) has confirmed amorphous phase mixed with polycrystalline features in the form of monoclinic structure. However, the polycrystalline CuO disappeared and changed to crystallite phase with increasing of annealing temperature. The values of bandgap energy (Eg) of the films were calculated using the absorbance data recorded by a spectrophotometer (UV-VIS). The calculated Eg using Tauc plot was about 2.45 eV which increased with increasing of annealing temperature. CuO thin films with high conductivity have been used to fabricate a hetrojunction solar cell of CuO/p-Si at 600°C which give Rs = 111Ω, Rsh = 7kΩ and a conversion efficiency of 1.24×10−4%.

Insights into stability, transport, and thermoelectric properties of transparent p-type copper iodide thin films

“…The negative slope obtained for CuO corresponds to a transport activation energy ( E a ) of 0.18 eV, similar to those previously reported for CuO films. 49…”

“…The negative slope obtained for CuO corresponds to a transport activation energy (E a ) of 0.18 eV, similar to those previously reported for CuO films. 49 Both structural and electrical characterization of the thermal stability under air of the g-CuI phase show a phase transition toward CuO between 200 and 220 1C, limiting the use of CuI exposed to air for temperature ranges above 200 1C.…”

Preparation and Characterization of CuO Nanostructured Thin Films by Chemical Bath Deposition

“…The crystallite size"( ave D ) is calculated using Scherrer's relation and dislocation density"(δ) were obtained using Eq. ( 2) below [33] and the results are shown in table 1.…”

“…These films are all polycrystalline and have a monoclinic crystal structure; no peaks on the XRD diagram identified as Cu2O were found, which suggests that they are made entirely of CuO molecules or that small amount of Cu2O probably present in the sample. At diffraction angles of 35.600 and 38.720, there are two conspicuous peaks ( 002) and ( 111), which indicate that they are favorable crystal planes of the CuO monoclinic crystal phase's nanorods and it's clear that the peak intensities in the thin films grew as the temperature increased, indicating that the crystallinity of the films increased [33].…”

Rod-like Nano-structures of Copper Oxide Prepared by Chemical Bath Deposition

“…and the reason is that the heat treatment increases the crystallite size. Hence, the energy of the tails decreases [32]. Tauc's equation was utilized to calculate the optical bandgap of the films [33] where  is a constant,  is the absorption coefficient,  h is the incident photon's energy, g E is the optical bandgap respectively.…”