Multifunctional ytterbium oxide buffer for perovskite solar cells.

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Perovskite solar cells (PSCs) require charge-selective layers for efficient operation.
• Buffer materials in p-type/intrinsic/n-type (p-i-n) PSCs facilitate electron transport and prevent degradation.
• Existing buffer materials have limitations, necessitating novel solutions.

Purpose of the Study:

• To introduce ytterbium oxide (YbO_x) as a chemically stable and multifunctional buffer material for p-i-n PSCs.
• To evaluate the performance and stability of PSCs utilizing YbO_x buffer layers.
• To demonstrate the broad applicability of YbO_x across different perovskite absorber bandgaps.

Main Methods:

• Scalable thermal evaporation deposition of YbO_x buffer layers.
• Fabrication and characterization of p-i-n PSCs with YbO_x buffers.
• Performance testing with narrow-, mid-, and wide-bandgap perovskite absorbers.
• Accelerated aging tests (ISOS-L-3) on encapsulated devices.

Main Results:

• PSCs with YbO_x achieved a certified power conversion efficiency exceeding 25% with a narrow-bandgap absorber.
• State-of-the-art efficiencies of 20.1% and 22.1% were obtained for wide- and mid-bandgap PSCs, respectively.
• Encapsulated devices demonstrated significantly enhanced stability under accelerated aging conditions.

Conclusions:

• YbO_x is a highly effective buffer material for high-performance and stable p-i-n PSCs.
• The material's versatility supports efficient PSCs across a spectrum of perovskite absorber types.
• This development contributes to the advancement of durable and efficient perovskite solar technology.