| Work Detail |
Researchers from China and Malaysia simulated a new structure for copper-zinc-tin sulfide (CZTS) cells with a tungsten oxide buffer layer and a kesterite layer on the back surface field. A simulated device with this configuration achieved an open circuit voltage of 1.2 V and a fill factor of 83.37%.
A group of researchers from China and Malaysia has proposed a new structure for copper-zinc-tin-sulfide (CZTS) thin-film solar cells in a bid to improve efficiency and use more environmentally friendly materials.
The team chose tungsten oxide (WO3) as the buffer layer based on properties and performance found in previous research, such as its high bandgap and “excellent electrical conductivity.” It was used to replace the cadmium sulfide (CdS) buffer layer, which the team says is toxic and expensive. Additionally, the team opted to apply a Cu2ZnSnSe4 (CZTSe)-based back surface field (BSF) between the absorber layer and the platinum (Pt) metal substrate.
In the study, one device was structured without the BSF layer, with zinc oxide (ZnO) as the window layer, WO3 as the buffer layer, CZTS as the absorber layer, and Pt as the metal substrate, which the researchers named the Pt/CZTS/WO3/ZnO structure. The other device had a similar structure, but with an additional CZTSe BSF layer sandwiched between the CZTS and Pt layers, which was named the Pt/CZTSe/CZTS/WO3/ZnO structure.
The group then analysed the structures with and without the BSF layer. They investigated how layer thickness, operating temperature, back-contact layers, acceptors and defects in the BSF layer affected performance using the SCAPS-1D solar cell capacitance software developed by Ghent University.
The comparison between the two structures showed that the addition of the BSF layer could increase the performance of the CZTS solar cell. The best results of the Pt/CZTSe/CZTS/WO3/ZnO device indicated an open-circuit voltage of 1.2 V, a fill factor of 83.37%, and a power conversion efficiency of 29.3%. According to the team, this was a better result than that of the solar cell without the BSF layer, whose efficiency was 23.01%.
In their concluding remarks, the scientists noted that industrial practices need to take into account material costs, environmental sustainability, and material defect density to achieve large-scale production. “Future research should focus on advancing the development and stability of multi-heterojunction solar cells, exploring metal ion doping, and improving thin film techniques,” they stated, asserting that this research should provide a new way to improve the performance of structurally similar solar cells to enable the industrialization of low-cost, high-efficiency photovoltaic cells.
The research is documented in “ Efficiency enhancement of CZTS solar cell with WO3 buffer layer using CZTSe BSF layer ,” published in Energy Reports . The research team consisted of scientists from Wuhan University (China), Multimedia University (Malaysia) and Xiamen University (Malaysia). |
