Properties enhancement of electrodeposited-Cu2O-based homojunction thin film solar cell using etching treatment

• Main Author: Mohd Ismail, Anis Zafirah
• Format: Thesis
• Language: English; English; English
• Published: 2022
• Subjects: T Technology (General)
• Online Access: http://eprints.uthm.edu.my/8400/1/24p%20ANIS%20ZAFIRAH%20MOHD%20ISMAIL.pdf; http://eprints.uthm.edu.my/8400/2/ANIS%20ZAFIRAH%20MOHD%20ISMAIL%20COPYRIGHT%20DECLARATION.pdf; http://eprints.uthm.edu.my/8400/3/ANIS%20ZAFIRAH%20MOHD%20ISMAIL%20WATERMARK.pdf; http://eprints.uthm.edu.my/8400/

The need for sustainable power generation has encouraged research into a variety of photovoltaic (PV) systems, which can cope with the global energy crisis in the future. Cuprous oxide (Cu2O) is a naturally p-type semiconductor with Eg of 1.6 to 2.1 eV and gains a wide spotlight as a layer in the photovoltaic device. Electrodeposition of Cu2O thin film is a well-known technique due to the low fabrication cost, controllable properties and low temperature needed. However, the reported efficiency value is still unsatisfactory to compete in the market. The low energy conversion efficiency is caused by lattice and thermal mismatch between heterojunction thin films. Therefore, Cu2O based homojunction thin film solar cell was developed. However, to fabricate homojunction Cu2O thin film is intricate due to highly resistive of n-Cu2O thin film. Thus, etching treatment via hydrothermal method was implemented on n-Cu2O thin film by potassium impurity that presents during the fabrication process. This will decrease the resistivity and ease the electrodeposited of p-Cu2O thin film. Moreover, transportation of minority carrier from the p- to n-Cu2O were improved. Diluted ethanol was used as a medium for etching treatment. The ethanol concentration and etching time were optimized. The properties and conversion efficiency were analyzed using XRD, FE-SEM, UV-vis, AFM, Four Point Probe and Solar Simulator, respectively. From EDX measurement, the composition of potassium decreased from 14.62% (as-deposited) to 2.52% of (etched n-Cu2O). The etched-n-Cu2O thin film was more crystalline and showed significantly improved properties. Thus, the improvement in the quality and purity of the Cu2O layer is crucial to increase the efficiency value. Through modifying the n-Cu2O thin film with etching treatment, a relatively high-power conversion efficiency (PCE) of 1.4833% was obtained from 0.018% as-deposited. Although a lot of improvement is still needed to meet up with the current trends of solar technology, it does prove that the properties and efficiency of homojunction-based Cu2O thin film solar cell incorporating with etching treatment at bottom layer of n-Cu2O is improved.