Understanding the Role of Transition Metal Oxides as Hole-Selective Contacts for Enhanced Efficiency in Selenium...

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Selenium solar cells (SeSCs) are promising for indoor energy harvesting and tandem applications.
• Hole transport layers (HTLs) in SeSCs are less explored compared to electron transport layers (ETLs).

Purpose of the Study:

• Investigate inorganic transition metal oxides (TMOs) like MoOₓ, WOₓ, and V₂Oₓ as HTLs in SeSCs.
• Optimize TMO thicknesses for improved device performance under various lighting conditions.

Main Methods:

• Fabrication and characterization of SeSCs with different TMO HTLs.
• Systematic optimization of TMO layer thicknesses.
• Performance evaluation under standard AM1.5G and indoor illumination.
• Interfacial analysis using Ultraviolet photoelectron spectroscopy (UPS) and TEM-EDS.

Main Results:

• Optimized TMO HTLs improved fill factor (FF) and reduced parasitic resistances, enhancing power conversion efficiencies (PCEs).
• A 20 nm MoOₓ HTL achieved a 5.5% PCE outdoors.
• A 10 nm V₂Oₓ HTL yielded over 10% PCE indoors across various light intensities.
• Interfacial studies revealed strong interactions and spontaneous MoSe₂ formation, suppressing recombination.

Conclusions:

• Inorganic TMOs are crucial for enhancing SeSC performance and selectivity.
• Optimized SeSCs with TMO HTLs are suitable for indoor photovoltaics and tandem applications.
• Further research into TMO-selenide interactions can unlock SeSC potential.