Pressure-Modulated Near-Infrared Photoluminescence of a Two-Dimensional Germanium Halide Perovskite

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Two-dimensional (2D) metal halide perovskites are promising for light-emitting diodes.
• Deep-red and near-infrared (NIR) emissions are typically limited by quantum and dielectric confinement effects.

Purpose of the Study:

• To explore pressure-modulated photoluminescence (PL) in 2D perovskites.
• To achieve deep-red and NIR emissions in 2D halide perovskites.
• To investigate pressure-induced changes in perovskite structure and optical properties.

Main Methods:

• Synthesis and characterization of (benzimidazolium)2GeI4 (BIM)2GeI4.
• Application of hydrostatic pressure to modulate PL emission.
• Analysis of pressure-induced exciton transfer and structural rearrangement.

Main Results:

• Achieved tunable narrowband deep-red to NIR emission from broadband NIR emission under hydrostatic pressure.
• Observed reversible piezochromism from orange to red to black.
• Demonstrated pressure-induced exciton transfer from self-trapped to free excitons.

Conclusions:

• Pressure engineering successfully extends 2D halide perovskite emission into the deep-red to NIR region.
• The observed effects are fully reversible upon pressure release.
• The findings indicate potential applications in red light emission and bioimaging.