Generating a Stable Higher-Symmetry CsPbI₃ Perovskite Phase in Ambient Conditions: Unveiling the Stabilization...

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Black-phase cesium lead iodide (CsPbI3) is crucial for high-efficiency optoelectronics but suffers from instability.
• Dimethylammonium iodide (DMAI) offers stabilization but with limited phase stability and lower efficiencies.

Purpose of the Study:

• To enhance the stabilization of black-phase CsPbI3 using DMAI through optimized conditions.
• To gain mechanistic insights into stabilization using experimental and theoretical analyses.
• To improve film morphology and optoelectronic device performance.

Main Methods:

• Systematic tuning of DMAI concentration, annealing temperature, and Cs+ substitution.
• Experimental characterization and theoretical analysis for mechanistic insights.
• Fabrication and testing of optimized perovskite photodiodes.

Main Results:

• Extended phase stability of black-phase CsPbI3 to 7 days under ambient conditions and over 16 months in a drybox.
• Improved film morphology with a minor Cs4PbI6 phase filling pinholes.
• Optimized photodiodes demonstrated low dark current, high external quantum efficiency, and a wide linear dynamic range.

Conclusions:

• Optimized DMAI concentration, annealing, and Cs+ substitution significantly enhance CsPbI3 phase stability.
• Mechanistic insights reveal reduced orthorhombic strain and octahedral tilting as key stabilization factors.
• The findings advance the development of stable and efficient perovskite optoelectronic devices.