An embedded interfacial network stabilizes inorganic CsPbI₃ perovskite thin films

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• The black perovskite phase of cesium lead iodide (CsPbI3) is highly promising for optoelectronic applications due to its desirable optical properties.
• However, CsPbI3's instability under ambient conditions, leading to rapid conversion to an inactive yellow phase, has hindered its practical use.

Purpose of the Study:

• To develop a method for stabilizing the black CsPbI3 perovskite phase against environmental degradation.
• To investigate the underlying mechanisms of phase destabilization and the effectiveness of a novel microstructural approach.

Main Methods:

• Coarse photolithography was employed to create a PbI2-based interfacial microstructure within CsPbI3 thin films.
• A tessellating microgrid structure was integrated into CsPbI3 films and devices to compartmentalize the material.
• The stability of the modified films and unencapsulated photodetectors was evaluated under ambient conditions.

Main Results:

• The microgrid structure significantly enhanced the long-term stability of the black CsPbI3 phase, maintaining it for over 2.5 years in a dry environment.
• This stabilization is attributed to an increased phase transition energy barrier and the confinement of yellow phase formation to isolated domains.
• Unencapsulated CsPbI3 perovskite photodetectors incorporating the microstructure demonstrated stable operation in ambient conditions.

Conclusions:

• The integration of a PbI2-based microgrid provides an effective and orthogonal stabilization strategy for CsPbI3 perovskite materials.
• This approach addresses the critical issue of phase instability, paving the way for the wider adoption of CsPbI3 in optoelectronic devices.
• The findings offer valuable insights into the phase transition dynamics of CsPbI3 and present a practical solution for device longevity.