Contact Selectivity Engineering in a 2 μm Thick Ultrathin c-Si Solar Cell Using Transition-Metal Oxides Achieving an...

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Ultrathin crystalline silicon (c-Si) solar cells offer potential for high efficiency but face challenges with recombination losses.
• Carrier-selective contacts are crucial for minimizing recombination at interfaces in solar cells.

Purpose of the Study:

• To demonstrate the integration of metal oxides as carrier-selective contacts for ultrathin c-Si solar cells.
• To enhance solar cell efficiency by suppressing contact recombination current through band offset engineering.

Main Methods:

• Fabrication of ultrathin c-Si solar cells (2 μm thickness) utilizing nickel oxide (NiOx) as a hole-selective contact.
• Integration of titanium oxide (TiOx) as an electron-selective contact in conjunction with NiOx.
• Characterization of device performance, including open-circuit voltage (Voc) and short-circuit current (Jsc).

Main Results:

• Achieved >10% efficiency in a 2 μm ultrathin c-Si solar cell without light-trapping using NiOx.
• Demonstrated a champion cell efficiency of 10.8% with the combined NiOx and TiOx integration.
• Observed significant enhancements in Voc and Jsc with single and double carrier-selective contacts.

Conclusions:

• Metal oxide integration, specifically NiOx and TiOx, effectively functions as carrier-selective contacts in ultrathin c-Si solar cells.
• Band offset asymmetry of metal oxides with Si suppresses recombination, leading to improved solar cell efficiency.
• The scalable fabrication process for NiOx and TiOx integration shows good device compatibility.