Unusual Spectrally Reproducible and High Q-Factor Random Lasing in Polycrystalline Tin Perovskite Films.

Area of Science:

• Materials Science
• Optics and Photonics
• Condensed Matter Physics

Background:

• Random lasing (RL) in semiconductor thin films is an area of active research.
• Achieving spectral stability in RL systems remains a significant challenge.
• Tin-based perovskites offer unique optoelectronic properties.

Purpose of the Study:

• To investigate spectrally reproducible near-infrared (near-IR) random lasing (RL) in chemically stabilized polycrystalline formamidinium tin triiodide perovskite films.
• To characterize the lasing properties, including Q-factor and amplified spontaneous emission (ASE) threshold.
• To elucidate the mechanism behind the observed spectral stability.

Main Methods:

• Fabrication of chemically stabilized polycrystalline formamidinium tin triiodide perovskite films.
• Characterization of random lasing properties using optical spectroscopy at 20 K.
• Analysis of spectral reproducibility and its correlation with material properties.

Main Results:

• Demonstrated spectrally reproducible near-IR RL with no fluctuation in lasing peak wavelength.
• Achieved a high quality (Q) factor of ≈10⁴ and a low ASE threshold of 2 µJ cm⁻² at 20 K.
• Observed unprecedented spectral stability in semiconductor thin film RL systems.

Conclusions:

• The spectral stability is attributed to the large inhomogeneous broadening of emitting centers in Sn-based perovskites, stemming from structural inhomogeneity.
• Lasing can occur simultaneously in spatially overlapped modes if their spectral separation exceeds the homogeneous linewidth.
• This discovery provides a mechanism for RL spectral stability in materials with inhomogeneous broadening, paving the way for cheap, narrow laser line sources.