High optical nonlinearity in low-dimensional halide perovskite polycrystalline films

Area of Science:

• Materials Science
• Optics and Photonics
• Solid-State Physics

Background:

• Low-dimensional halide perovskites are promising for optoelectronic applications.
• Understanding their nonlinear optical (NLO) properties is crucial for device design.
• Polycrystalline films offer a scalable alternative to single crystals.

Purpose of the Study:

• To investigate the nonlinear optical properties of ethylammonium (EA) and butylammonium (BA) based halide perovskite films.
• To compare the NLO behavior of two-dimensional (BA)2PbI4 and one-dimensional EAPbI3.
• To elucidate the relationship between dimensionality and NLO response.

Main Methods:

• Utilized the Z-scan technique to measure nonlinear absorption and nonlinear refractive index.
• Fabricated polycrystalline halide perovskite films with varying cation structures.
• Analyzed the optical properties across the band-edge.

Main Results:

• Two-dimensional (BA)2PbI4 showed a transition from saturable absorption (SA) to reverse-SA across the band-edge.
• The NLO parameters of (BA)2PbI4 were significantly smaller than bulk counterparts.
• One-dimensional EAPbI3 exhibited SA behavior both above and below the band-edge.
• Polycrystalline EAPbI3 demonstrated NLO parameters comparable to single crystals.

Conclusions:

• Dimensionality significantly influences the nonlinear optical properties of halide perovskites.
• The high dielectric contrast in 1D EAPbI3 contributes to its robust NLO performance.
• Polycrystalline halide perovskites, particularly 1D structures, hold potential for NLO applications.