Wide Bandgap Tellurium Oxide Semiconductor as A Back Contact Modifier for Efficient n-i-p Sb₂Se₃ Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Semiconductor Physics

Background:

• Wide-bandgap, p-type semiconductor layers are vital for antimony selenide (Sb₂Se₃) solar cells, enhancing carrier confinement and minimizing interface recombination.
• Effective back contact modification is crucial for improving the performance of Sb₂Se₃ solar cells.

Purpose of the Study:

• To investigate the application of a tellurium (Te) thin layer, oxidized in situ to tellurium oxide (TeO₂), as a back contact modification in superstrate Sb₂Se₃ solar cells.
• To evaluate the impact of Te and TeO₂ layers on device performance, including built-in potential, depletion width, recombination, and hole transport.
• To explore the defect passivation capabilities of TeO₂ for selenium vacancies (V_Se) in Sb₂Se₃ absorbers.

Main Methods:

• Fabrication of superstrate Sb₂Se₃ solar cells incorporating a tellurium (Te) thin layer.
• In situ oxidation of the Te layer to form tellurium oxide (TeO₂).
• Characterization of the electrical and optical properties of the Te and TeO₂ layers and their interfaces with Sb₂Se₃.
• Performance evaluation of the solar cells, including open-circuit voltage and power conversion efficiency.

Main Results:

• Both Te and TeO₂ layers improved the built-in potential and depletion width of Sb₂Se₃ solar cells.
• Nonradiative recombination at the back interfaces was reduced by the presence of Te and TeO₂ layers.
• The TeO₂ layer facilitated better hole transportation due to favorable band alignment with Sb₂Se₃.
• TeO₂ effectively passivated selenium vacancies (V_Se) in Sb₂Se₃ absorbers.
• Sb₂Se₃ solar cells with TeO₂ achieved a high open-circuit voltage of 0.463 V and a champion power conversion efficiency of 9.67%.

Conclusions:

• The in situ formed TeO₂ layer serves as an effective back contact modification for high-performance Sb₂Se₃ solar cells.
• Tellurium oxide passivation of selenium vacancies and improved interfacial properties contribute significantly to enhanced device performance.
• This strategy offers a promising route for advancing vacuum-coated Sb₂Se₃ solar cell technology.