Anisotropic 2D excitons unveiled in organic–inorganic quantum wells

Abstract

<p>Two-dimensional (2D) excitons arise from electron-hole confinement along one spatial dimension. Such excitations are often described in terms of Frenkel or Wannier limits according to the degree of exciton spatial...</p>

Understanding the Synthetic Pathway to Large-Area, High-Quality [AgSePh]∞ Nanocrystal Films

“…This is an effect of the anisotropic excitonic resonances and indicative of the different in-plane versus out-of-plane contributions, as reported elsewhere. 9 Instead, even just a mild O2 plasma oxidation of the silver film leads to a completely different result (after 30 min PhSeH reaction), characterized by a nanocrystalline morphology and a characteristic excitonic resonance (Figure S4b,d, respectively). Oxygen plasma was chosen for achieving a higher control over the silver oxidation homogeneity compared to the UV ozone lamp used in previous studies.…”

“…9 The silver benzeneselenolate [AgSePh]∞ is part of a metal-organic chalcogenide (MOC) family where silver and chalcogen atoms form 2D inorganic planes separated by pairs of phenyl rings held together in the out-of-plane direction by Van der Waals forces (see Figure 1a for the extended molecular structure), providing effective quantum confinement along the [001] crystal direction. 9 The first synthesis of [AgSePh]∞ reported by Cuthbert et al 10 was obtained by reacting lithium phenylselenolate, generated in situ from the reductive cleavage of PhSe-SiMe3 with alkyl lithium reagents, with triphenylphosphine solubilized AgCl, yielding the extended structure [Ag(SePh)]∞. The crystals were used to refine the crystal structure, but no spectroscopic data were presented (although a "broad absorption" is reported to be peaked at  = 435 nm).…”

“…Starting from these reports, a first attempt to make continuous large area films to enable spectroscopic experiments has been recently reported by using silver thin films oxidized by UV ozone lamp, subsequently reacted with vapor benzeneselenol. 9 This reaction reportedly yielded square centimeters-size areas covered by nanocrystal films. Nevertheless, the control over the reaction parameters and the understanding of the reaction pathway has been so far missing.…”

Chemical crystallography by serial femtosecond X-ray diffraction

“…Mithrene and tethrene both have strong light-matter interactions; yellow mithrene has a direct bandgap and emits blue light with a short photoluminescent lifetime (approximately 50 ps); 18 whereas orange tethrene has an indirect bandgap 36 and emits broadly with a longer lifetime (approximately 1 ns) (Fig. 4j, k).…”

Investigation of Nucleation and Growth at a Liquid–Liquid Interface by Solvent Exchange and Synchrotron Small-Angle X-Ray Scattering

“…Mithrene, silver (I) benzeneselenolate, is a well understood example of this material class. It is a direct gap semiconductor with a large exciton binding energy, that exhibits optical properties similar to transition metal dichalcogenide monolayers like MoS 2 ( Chen et al, 2017 ; Trang et al, 2018 ; Maserati et al, 2020 ; Yao et al, 2020 ). A classic synthetic method for mithrene is nucleation and growth occurring at an oil-water interface, in Figure 1A an image of the toluene-water interface and a schematic in Figure 1B help illustrate this synthetic environment.…”