Stoichiometric MACl/PbCl₂ Additive Engineering for Improved Reproducibility and Carrier Lifetime in FA/Cs...

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Chloride additives are crucial for high-efficiency perovskite solar cells (PSCs).
• Methylammonium chloride (MACl) is widely used but leads to process sensitivity and irreproducibility.
• Understanding MACl's impact on film heterogeneity is key for PSC development.

Purpose of the Study:

• To investigate the impact of MACl processing on mixed-halide perovskite films.
• To identify the sources of irreproducibility in MACl-assisted PSC fabrication.
• To develop a more stable and reproducible chloride additive for PSCs.

Main Methods:

• Systematic investigation of MACl-processed FA0.9Cs0.1Pb-(I0.9Br0.1)3 films.
• Utilized X-ray diffraction (XRD), atomic force microscopy (AFM), and time-resolved photoluminescence (TRPL).
• Developed and tested a reduced-volatility MCP chloride additive derived from MACl/PbCl2.

Main Results:

• MACl processing induced compositional and structural heterogeneity, leading to PL quenching and increased recombination.
• The novel MCP chloride additive (MCP-5) yielded homogeneous films with extended carrier lifetimes (1.3-1.6 μs).
• MCP-5 based PSCs showed improved PCE (12.03%), higher open-circuit voltage, reduced variability, and better humidity retention compared to MACl-treated devices.

Conclusions:

• MACl-induced heterogeneity is a major cause of irreproducibility in PSCs.
• MCP chloride additive processing offers a promising route to reproducible mixed-halide PSCs.
• Further long-term stability studies are needed for MCP-based PSCs.