Trap and transfer. two-step hole injection across the Sb2S3/CuSCN interface in solid-state solar cells

Area of Science:

• Materials Science
• Solid-state physics
• Photovoltaics

Background:

• Extremely thin absorber (ETA) or solid-state quantum-dot-sensitized solar cells (QDSCs) rely on efficient charge separation.
• Hole transfer from the absorber to the p-type hole conductor is crucial for performance in these devices.

Purpose of the Study:

• To independently investigate the hole transfer dynamics from Sb2S3 absorber to CuSCN hole conductor in ETA solar cells.
• To understand the limiting factors in charge separation for Sb2S3-based solar cells.

Main Methods:

• Fabrication of Sb2S3/CuSCN ETA solar cells with 3.3% power conversion efficiency.
• Utilizing transient absorption spectroscopy to monitor photogenerated hole transfer.

Main Results:

• Photogenerated holes in Sb2S3 localize on sulfur atoms, forming sulfide radical (S(-•)) species.
• Hole transfer from Sb2S3 to CuSCN occurs with a time constant of 1680 ps.
• Spectroscopic observation of S(-•) species provided direct evidence of hole transfer dynamics.

Conclusions:

• Elucidating the Sb2S3 to CuSCN hole transfer mechanism is key to understanding charge separation in these solar cells.
• This research provides insights for designing higher efficiency Sb2S3 solar cell architectures.