Description
This research assesses the potential of Zn(1−x)MgxO (ZMO) as a non-toxic, wide band gap n-type layer for integration into emerging Sb2S3 solar cells. The ZMO films with Mg content varying from 5 to 20 at% were deposited by magnetron sputtering onto molybdenum and double-polished sapphire substrates. The chemical, electronic, and optical properties were investigated by X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), reflection electron energy loss spectroscopy (REELS), and optical transmittance (UV-Vis), respectively. Our findings reveal an increase in the bandgap (Eg) of ZMO from 3.3 to 3.7 eV with increasing Mg content from 5% to 20 at%. Moreover, spatial mapping indicated variations in the films' energy bandgap (Eg), valence band maximum (VBM), and Zn/Mg ratio over a distance of 10 cm. Generally, the ZMO films show lower Eg values at the center than the edges, consistent with findings from surface-sensitive REELS and bulk-sensitive UV-Vis methods. The same trend was observed for the chemical composition of the films (Zn/Mg ratio), which directly relates to the Eg. Notably, the spatial fluctuations in the ZMO film properties become more pronounced with increasing Mg content, whereas deposits with a low Mg content of 5% show less intense fluctuations. Moreover, the VBM did not show a consistent trend with Mg content. Overall, the knowledge of the spatial fluctuations of the electronic properties of the films is crucial for elucidating the band alignment at the absorber/buffer interface, particularly the conduction band offset.1,2 Further discussion will provide insights into the mechanism leading to the preferential sputtering of Zn compared to Mg. Future work will focus on integrating ZMO as an n-type buffer layer in Sb2S3 solar cell fabrication.References:
(1) Gansukh, M.; Li, Z.; Rodriguez, M. E.; Engberg, S.; Martinho, F. M. A.; Mariño, S. L.; Stamate, E.; Schou, J.; Hansen, O.; Canulescu, S. Energy Band Alignment at the Heterointerface between CdS and Ag-Alloyed CZTS. Sci Rep 2020, 10 (1). https://doi.org/10.1038/s41598-020-73828-0.
(2) Zhao, Y.; Wang, S.; Jiang, C.; Li, C.; Xiao, P.; Tang, R.; Gong, J.; Chen, G.; Chen, T.; Li, J.; Xiao, X. Regulating Energy Band Alignment via Alkaline Metal Fluoride Assisted Solution Post-Treatment Enabling Sb2(S,Se)3 Solar Cells with 10.7% Efficiency. Adv Energy Mater 2022, 12 (1). https://doi.org/10.1002/aenm.202103015.
| Period | 26 Jun 2024 → 28 Jun 2024 |
|---|---|
| Held at | University of Verona, Italy |
| Degree of Recognition | International |