Strain Engineering of Two-Dimensional Hybrid Perovskites with Band Edge Modulation and Charge Separation

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) perovskites are promising materials for optoelectronic applications.
• Strain engineering is a key strategy to tune the properties of 2D perovskites.
• Understanding the impact of strain on electronic band structure is crucial for device optimization.

Purpose of the Study:

• To investigate the effect of biaxial strain on the electronic properties of 2D Dion-Jacobson perovskites.
• To elucidate the mechanisms behind strain-induced changes in the conduction band minimum (CBM).
• To explore the implications of these changes for charge separation and carrier lifetime in perovskite solar cells.

Main Methods:

• First-principles calculations.
• Nonadiabatic molecular dynamics simulations.
• Analysis of electronic band structure and charge carrier dynamics under varying strain conditions.

Main Results:

• Biaxial strain exceeding 6% induces an abnormal transition of the CBM from inorganic to organic contributions in (3AMPY)PbI4.
• This transition is driven by the interplay between Pb-I bonding and organic-inorganic hydrogen bonding.
• Strain-induced CBM reconfiguration enhances charge separation, shortens quantum coherence time, and suppresses nonadiabatic coupling, thereby increasing charge carrier lifetime, especially under tensile strain.

Conclusions:

• A novel strain-engineering strategy is proposed for modulating band edges and charge transport in 2D perovskites.
• The findings provide valuable insights for the rational design of high-performance 2D perovskite solar cells.
• Strain engineering offers a powerful tool to optimize the optoelectronic properties of 2D materials.