Revealing Performance-Limiting Buried Interfaces in Layered Dion-Jacobson Lead-Iodide Perovskites.

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Dion-Jacobson (DJ) 2D perovskites offer enhanced stability over 3D counterparts for solar applications.
• Interfacial imperfections limit the optoelectronic performance of DJ 2D perovskites.
• A fundamental understanding of buried interfacial properties is lacking.

Purpose of the Study:

• To investigate interfacial structure-property relationships in DJ 2D perovskites.
• To identify and characterize heterogeneities at buried interfaces.
• To develop strategies for improving interfacial properties and device performance.

Main Methods:

• Direct probing of buried interfaces using combined spectroscopic and microscopic techniques.
• Analysis of multiscale heterogeneities including phase polydispersity and structural disorder.
• Application of a sulfate-based inner-sphere complexation strategy for crystal passivation.

Main Results:

• Buried interfaces exhibit higher concentrations of heterogeneities (phase polydispersity, disorder, nonemissive domains) than top surfaces.
• The passivation strategy homogenized crystal growth and passivated crystal terminations at buried interfaces.
• Nonradiative recombination was suppressed, and ultrafast interphase carrier transfer was promoted.

Conclusions:

• DJ 2D perovskite solar cells achieved a record 20.7% power conversion efficiency.
• The developed strategy improved environmental stability compared to 3D perovskites.
• Establishing the link between buried interface heterogeneity and optoelectronic performance is crucial for DJ 2D perovskite development.