Controllable Synthesis of Monodispersed Fe_1–xS₂ Nanocrystals for High-Performance Optoelectronic Devices

Abstract

The optical properties of stoichiometric iron pyrite (FeS2) nanocrystals (NCs) are characterized by strong UV–Visible (UV–Vis) absorption within the cutoff while negligible absorption beyond the cutoff in near-infrared and longer wavelengths. Herein, we show this bandgap limitation can be broken through controllable synthesis of nonstoichiometric Fe1–x S2 NCs (x = 0.01–0.107) to induce localized surface plasmonic resonance (LSPR) absorption beyond the cutoff to short-wave infrared spectrum (SWIR, 1–3 μm) with remarkably enhanced broadband absorption across UV–Vis–SWIR spectra. To illustrate the benefit of the broadband absorption, colloidal LSPR Fe1–x S2 NCs were printed on graphene to form LSPR Fe1–x S2 NCs/graphene heterostructure photodetectors. Extraordinary photoresponsivity in exceeding 4.32 × 106 A/W and figure-of-merit detectivity D* > 7.50 × 1012 Jones have been demonstrated in the broadband of UV–Vis–SWIR at room temperature. These Fe1–x S2 NCs/graphene heterostructures are printable and flexible and therefore promising for practical optical and optoelectronic applications.

Shape-Controlled Synthesis of Colloidal Nanorods and Nanoparticles of Barium Titanium Sulfide

“…There are likely multiple factors that influence both the structure and the absorbance peak position; for instance, the Ba/Ti stoichiometry in the crystal lattice is also known to influence c. 25 These results are reminiscent of the properties of nanomaterials, such as copper sulfide, Cu 2−x S, and related materials, where off-stoichiometric compositions give rise to strong absorbance peaks in the visible-to-NIR regions which arise from localized surface plasmon resonances (LSPRs) due to the presence of free charge carriers (holes, in the case of Cu 2−x S). 35−39 It is possible that a similar phenomenon in BaTiS y is responsible for our observations, which would make BaTiS y a relatively rare example of a non-copper-containing chalcogenide nanocrystal exhibiting LSPR resonances; 40 we do note that the observation of an LSPR absorbance in TiS 2 nanosheets has been proposed. 41 The fact that the energy of the observed NIR absorbance peak increases with increasing off-stoichiometry would be consistent with this hypothesis.…”

Ligands Anchoring Stabilizes Metal Halide Perovskite Nanocrystals

“…The R* of the CsPbBrI 2 IPNCs/graphene and LA‐CsPbBrI 2 IPNCs/graphene photodetectors are 8.66 × 10 4 and 9.18 × 10 4 A W −1 , respectively. The specific detectivity ( D *) can be calculated based on the equation D* = ( S × ∆ f ) 1/2 /NEP, [ 59,60 ] where ∆ f is band width in Hz, NEP is the noise equivalent power with the unit of A /Hz 1/2 , which is defined as the minimum optical power required to obtain a unity signal‐to‐noise ratio in a 1 Hz bandwidth. NEP will be calculated by equation , where is the mean square noise current and can be obtained from the spectra density of the noise power.…”

High-Gravity-Assisted Synthesis of Surfactant-Free Transparent Dispersions of Monodispersed MgAl-LDH Nanoparticles

“…Monodispersed nanoparticles, which exhibit a lot of size- and shape-dependent phenomena, have been studied in depth due to their excellent dispersibility, specific morphologies, and functions as building blocks in synthesizing advanced materials. In the past decade, many monodispersed nanoparticles have been achieved, including noble metals, metal oxides, and some other metallic compounds. − However, monodispersed nanoparticles of metal hydroxides have been rarely reported, especially for LDHs. Duan and co-workers realized the preparation of MgAl-CO 3 LDH nanoparticles with the size of 60–80 nm using a colloid mill followed by a separate aging process.…”