Nickel Chlorophyll-Derived Hole Transport Materials for Stable and Efficient Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Organic Chemistry

Background:

• Hole-selective layers (HSLs) are essential for efficient and stable perovskite solar cells (PSCs).
• Chlorophylls (Chls) and their analogs possess advantageous optoelectronic properties for photovoltaic applications.
• Dopant-free Chl-based materials for HSLs are underexplored, with current power conversion efficiencies (PCEs) below 19%.

Purpose of the Study:

• To investigate three nickel chlorins (NiChls) as monomers for functional HSLs in PSCs.
• To explore the impact of chemical modification on the performance of Chl-based HSLs.
• To develop high-performance, dopant-free HSLs for next-generation PSCs.

Main Methods:

• Synthesized three nickel chlorins (NiChls): NiChl-Oxo, NiChl-Deoxo, and NiChl-CN, with NiChl-Deoxo and NiChl-CN derived from NiChl-Oxo via chemical modification.
• Fabricated polymerized NiChl films using electrochemical polymerization for use as HSLs.
• Fabricated and characterized perovskite solar cells (PSCs) utilizing the developed NiChl-based HSLs.

Main Results:

• Achieved a record PCE of 21.8% for NiChl-Deoxo-based PSCs, a significant improvement over existing Chl-based PSCs.
• Attained a high fill factor of 83.8% in the NiChl-Deoxo-based devices.
• Demonstrated exceptional long-term stability for the developed PSCs.

Conclusions:

• Strategic molecular modifications of nickel chlorins can significantly enhance their performance as hole-selective layers.
• The developed dopant-free NiChl-based HSLs offer a promising pathway for high-efficiency and stable perovskite solar cells.
• This research advances the application of chlorophyll analogs in next-generation photovoltaic technologies.