Combined simulation and experimental study on spectral absorbance of partially disordered MoSe₂ nanospheres

Abstract

It is important to clarify the role and possible applicability of partially disordered structures in photonics, but there is still a lack of an effective method for it. Here, we investigate partially disordered MoSe2 nanospheres experimentally regarding their morphology and absorption spectrum in broadband wavelengths and propose an optical simulation with 3D finite-difference time-domain method to explain the crucial impacts of morphological parameters on optical responses. The experimental spectral absorbance of MoSe2 nanospheres reveals a strong light-absorbing character in broadband wavelengths. The simulated spectral curves coincide with the experimental results by adjusting morphological parameters, i.e., the statistics of size and the number of layer, and the linear correlation coefficient between the simulated and experimental spectral curves is up to 0.94. The disorder plays a key role in the high light-absorption feature, and the feature originates from anti-reflection, defective state absorption, multiple light scattering and coherent diffusion effects. The results not only deepen the understanding of disordered photonics in semiconductor nanostructures, but also provide a simulation approach to optimize experimental designs.

A Single MoSe2 Fluffy Nanosphere for Localized Light Confinement

“…This feature leads to an essential difference in localized effectiveness within a smooth sphere (Figure d). Furthermore, there are three main absorption behaviors during the light propagation: resonant absorption, defective state absorption, and free-carrier absorption. , The number of photogenerated carriers G ( L ) of MoSe 2 can be expressed as G false( L false) = false( 1 − R false) I 0 S · h ν α e − α L where R is the surface reflectivity, I 0 is the incident light intensity, S is the incident area, hν is the incident photonic energy, α is the absorption coefficient, and L is the propagation length. The smaller the surface reflectivity, the more electron–hole pairs are produced.…”

“…Furthermore, there are three main absorption behaviors during the light propagation: resonant absorption, defective state absorption, and free-carrier absorption. 16,31 The number of photogenerated carriers G(L) of MoSe 2 can be expressed as 32…”