Halide Anion-Controlled Transition from Charge Transfer to Energy Transfer in Type-II 2D Perovskite Heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Interlayer carrier relaxation in type-II heterostructures is usually dominated by charge transfer (CT) due to electron-hole separation.
• This process is crucial for understanding and designing optoelectronic devices.

Purpose of the Study:

• To investigate the effect of halide anion substitution on carrier relaxation pathways in 2D organic-inorganic hybrid perovskite heterostructures.
• To explore the transition from charge transfer (CT) to energy transfer (ET) dominated relaxation.

Main Methods:

• Fabrication of type-II heterostructures using 2D organic-inorganic hybrid perovskites.
• Experimental characterization of carrier relaxation dynamics.
• Density functional theory (DFT) calculations to analyze interfacial electronic structure.

Main Results:

• In heterostructures with identical halide anions, CT dominates carrier relaxation.
• Substituting iodide (I-) with bromide (Br-) in BA2PbBr4/BA2PbI4 heterostructures switches the dominant pathway from CT to ET.
• DFT calculations show halide substitution alters interfacial electronic structure, suppressing charge separation and favoring dipole-dipole coupling.

Conclusions:

• Halide anion substitution is an effective strategy to control interfacial excitonic dynamics in 2D perovskite heterostructures.
• This manipulation enables a switch between charge transfer and energy transfer relaxation pathways.
• Provides insights for designing novel perovskite-based excitonic and optoelectronic devices.