A Comparison of Optical Properties of CuO and Cu<sub>2</sub>O Thin Films for Solar Cell Applications

Abstract

Solar energy is becoming more popular and widespread, and consequently, the materials to manufacture solar cells are becoming more limited and costly. Therefore, in order to keep solar energy affordable and available, we must research alternative materials such as copper oxides. Some benefits of copper oxides include being available in abundance, affordable, low toxicity, low bandgap, and a high absorption coefficient-all of which contribute to it being a valuable interest for the manufacturing of solar cells. In this study, CuO thin films were synthesized utilizing RF sputtering technique with deposition occurring at room temperature followed by thermal annealing between 100˚C and 400˚C and using different gases, oxygen (O 2 ) (oxidizing and reactive gas) and nitrogen (N 2 ) (inert gas), besides air. Afterwards, these thin films were evaluated for a range of wavelengths: 200 -400 nm (UV spectrum), 400 -700 nm (Visible spectrum), and 700 -800 nm (IR spectrum), for both, optical transmittance and photoluminescence. In addition, the CuO results were compared to our Cu 2 O results from a previous study to assess their differences. In the results of this study, the CuO thin film initially had a bandgap of 2.19 eV at room temperature, and by increasing the annealing temperature to different levels, the bandgap decreased respectively. The presence of air in the chamber allowed for the highest decrease, followed by the nitrogen (N 2 ) and the lowest decrease was observed in the presence of oxygen (O 2 ). This was reflected in the decrease in the bandgap values from 2.19 eV (room temperature) to 2.05 eV for the films annealed at 400˚C.

Study the Effect of Copper Oxide Nanorods Enhanced by Silver Nanoparticles on the Highly Sensitive Gas Sensor

“…(3 a), indicates the purity of this thin film. These values match to the energy gaps of direct gap of p-type CuO [30,31]. Energy gap values showing that a direct allowed transition was the cause of the absorption edge [32].…”

Influence of Deposition Parameters for Cu2O and CuO Thin Films by Electrodeposition Technique: A Short Review

“…CuO found to exhibit corrosion resistance as a result of interaction between copper and oxygen in the air to produce protective oxide in the form of thin layers covers the substrate. Usually, CuO with oxidation number having higher value is found to be thermally more stable than Cu 2 O. CuO is not soluble in organic and inorganic solvents; however, it is dissolved in the solution of ammonia [45]. The structure of CuO is monoclinic, whereas the structure is found to be cubic in electrodeposition [46,47].…”

High Performance of Nanostructured Cu2O-Based Photodetectors Grown on a Ti/Mo Metallic Substrate

“…Both CuO and Cu 2 O are stable forms of copper oxides and have numerous applications as a result of their electrical and optical characteristics [9][10][11]. They are p-type semiconductors with small band gaps that can recognize a wide range of light, including UV, visible, and infrared radiation [12,13].…”