Light scattering and random lasing in aqueous suspensions of hexagonal boron nitride nanoflakes

Abstract

Liquid phase exfoliation allows large scale production of 2D materials in solution. The particles are highly anisotropic and strongly scatter light. While spherical particles can be accurately and precisely described by a single parameter-the radius, 2D nanoflakes, however, cannot be so easily described. We investigate light scattering in aqueous solutions of 2D hexagonal boron nitride nanoflakes in the single and multiple scattering regimes. In the single scattering regime, the anisotropic 2D materials show a much stronger depolarization of light when compared to spherical particles of similar size. In the multiple scattering regime, the scattering as a function of optical path for hexagonal boron nitride nanoflakes of a given lateral length was found to be qualitatively equivalent to scattering from spheres with the same diameter. We also report the presence of random lasing in high concentration suspensions of aqueous h-BN mixed with Rhodamine B dye. The h-BN works as a scattering agent and Rhodamine B as a gain medium for the process. We observed random lasing at 587 nm with a threshold energy of 0.8 mJ.

Graphdiyne Nanosheets for Multicolor Random Lasers

“…As the pump intensity increases, sharp emission spikes emerge on a broad background, which indicates the successful generation of random lasers. The random laser performane is similar to recently reported experimental results in MXene quantum dots, 16 boron nitride nanoflakes, 15 and ZnO nanowires. 10 It can be seen that the random laser threshold increases as a function of the pump wavelength.…”

“…Yet, the biomedical toxicity, narrow tuning of the optical frequency, and intrinsic instability of the materials remain hurdles to overcome. Two-dimensional (2D) materials with extraordinary optoelectronic properties like atomic-layer-dependent energy structures and high emission yields have recently been receiving increased attention. ,− Among them, graphdiyne (GDY), a novel 2D graphene allotrope with unique sp–sp 2 carbon hybridization, uniform pores, highly p-conjugated structure, and high biocompatibility, has set up a new wave of investigations in carbon-based nanotechnologies in the recent decade. − To date, GDY has been intensively studied in various application fields, including catalysis, energy storage, sensing, and biomedical treatments . Different from gapless graphene, single-layer GDY is ascribed to be a narrow-band-gap semiconductor, with a band gap of around 0.44–1.47 depending on the calculation methods .…”

Spectroscopic Size and Thickness Metrics for Liquid-Exfoliatedh-BN

“…Spectra are shown in figure 2A and show a peak at ~6.1 eV (205 nm). Aside from this peak, the spectra are dominated by a broad scattering background, 5,17,39 especially for the fractions containing larger nanosheets. Clearly the shape of this scattering background is highly dependent on nanosheet size.…”

Review of Open Cavity Random Lasers as Laser-Based Sensors

“…However, over years of study it was found that this type of lasing was found in a very wide range of systems of different scattering strength, far beyond the regime where localization conditions could possibly play a role . Different particle sizes looking into the effect of scattering in random lasing emission have been investigated with varying gain mediums. − Further investigations yielded the relation of random lasing with photon random walk that defines the transport mean free path of these photonsa parameter to understand how far photons can travel in a highly scattered medium of a random laser that has gain. − Below, we will briefly discuss some of the basic principles of light scattering of importance to understand the behavior of open cavity random lasers.…”