Homogenized chlorine distribution for >27% power conversion efficiency in perovskite solar cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Spatial heterogeneity in halogen distribution within perovskite thin films limits solar cell power conversion efficiency (PCE) and stability.
• Pronounced through-film inhomogeneity of chlorine distribution was observed in formamidinium lead iodide films using methylammonium chloride.

Purpose of the Study:

• To investigate methods for homogenizing chlorine distribution in perovskite thin films.
• To improve the PCE and operational stability of perovskite solar cells.

Main Methods:

• Incorporation of alkali metal oxalates into perovskite films.
• Analysis of chlorine distribution and defect suppression.
• Fabrication and testing of perovskite solar cells under continuous maximum power point tracking (MPPT) and thermal aging.

Main Results:

• Alkali metal oxalates effectively homogenized chlorine distribution through thermal dissociation and selective chloride ion binding.
• Incorporation of these compounds suppressed surface defects and eliminated interfacial barriers.
• Achieved a certified steady-state PCE of 27.2% and devices retained 86.3% of initial PCE after 1529 hours of MPPT under 1 Sun.

Conclusions:

• Alkali metal oxalates are effective additives for enhancing perovskite solar cell performance and stability.
• Homogenized chlorine distribution leads to reduced defects and improved device longevity.
• The developed method offers a promising pathway for highly efficient and stable perovskite solar cells.