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Doping semiconductor nanomaterials with manganese ion (Mn2+) introduce a well‐defined photoactive d‐d level within the band structure, paving the way for diverse applications. Although Mn doping in single‐layer 2D hybrid perovskites (n = 1) has been extensively studied, limited research has been conducted on doping with modulation of the layer thickness. Herein, Mn2+ doping in hybrid 2D perovskite nanoplatelets (NPLs), L2An‐1[Pb1‐xMnx]nBr3n+1 (where L = butylammonium, A = methylammonium), with variations in Mn concentration (x = 0–0.60) and layer thickness (n = 1–3) is reported. Substitutional doping of Mn significantly increases the photoluminescence quantum yield as well as the rate of energy transfer efficiency, which strongly depends on the layer thickness of NPLs. The Mn concentration in 2D NPLs determines the rate of forward and backward energy transfer. Low‐temperature emission spectra allow to determine thickness‐dependent exciton binding energy for Mn‐doped 2D NPLs (x = 0.5) with values of 410 ± 11 meV (n = 1), 188 ± 9 meV (n = 2), and 151 ± 17 meV (n = 3). The faster dissociation of band‐edge excitons into free carriers at Mn2+ sites results in high brightness with an excellent CRI of 89.2 for the white light‐emitting diode. [ABSTRACT FROM AUTHOR]

Quantum dot light emitting devices (QLEDs) show promise for displays, with polyethylenedioxythiophene:polystyrene (PEDOT:PSS) commonly used as a hole injection layer (HIL) due to its high conductivity and work function. However, PEDOT:PSS-based QLEDs face an energy barrier, reducing efficiency. Herein, in this work, we used the rapid thermal annealing (RTA) process to improve the conductivity by controlling the RTA processing time which reduced the interfacial resistance. This improves charge balance and long-term stability by preventing electron leakage. The optimized V2O5/PEDOT:PSS-based QLED, with an EQE of 18%, CE of 77 cd A−1 and maximum luminance of 23 242 cd m−2, outperforms the PEDOT:PSS-based counterpart. This highlights the strategic superiority of V2O5 HIL in our QLED. [ABSTRACT FROM AUTHOR]

Zero‐dimensional (0D) 5s2‐metal halide (MH) materials offer potential for use in solid‐state lighting, optical thermography, and scintillation applications. The organic components of most highly luminescent materials are inherently unstable under moisture and thermal stress, which restricts their practical use in advanced applications. Hence, highly luminescent and stable inorganic luminescent materials are required. In this work, to the best of current knowledge, a 0D completely inorganic luminescent member of K2SbCl5 that exhibits orange emission at 610 nm with an 80% photoluminescence quantum yield (PLQY) is reported for the first time. Density functional theory calculations reveal that the [SbCl5]2‐ square pyramidal units are the only optically active emission centers in K2SbCl5. The white light‐emitting device utilizing K2SbCl5 demonstrates impressive performance metrics, boasting a substantial color rendering index (CRI) of 94 and an exceptional luminous efficacy of 118.1 lm W−1. Hence, this isolated [SbCl5]2−square pyramidal environment serves as a design principle for the development of highly efficient inorganic Sb3+‐based luminescent materials for future optoelectronic applications. [ABSTRACT FROM AUTHOR]

Classical theories of dielectric friction make two critical assumptions: (i) friction due to van der Waals (vdW) forces is described by hydrodynamic drag and is independent of the ionic charge and (ii) vdW and electrostatic forces are statistically independent. Both assumptions turn out to be incorrect when tested against simulations of anions and cations with varying charge magnitude dissolved in water. Both the vdW and electrostatic components of the force variance scale linearly with the ionic charge squared. The two components are strongly anticorrelated producing simple relations for the total force variance in terms of self-variances. The inverse diffusion constant scales linearly with the charge squared. Solvation asymmetry between cations and anions extends to linear transport coefficients. [ABSTRACT FROM AUTHOR]

Mobility of ions in polar liquids is diminished when the ionic charge is increased. This phenomenon, known as dielectric friction, is caused by the retarded response of the liquid's dipoles to the charge movement. Linear response theories predict linear scaling of the inverse diffusion coefficient with the squared ionic charge. This prediction is analyzed here by molecular dynamics simulations of model ions with fractional charge q in the simple point charge water and by microscopic theory formulated in terms of the dynamic electric-field susceptibility of the solvent. The results of the analytical theory, and of its dielectric continuum limit, are in excellent agreement with simulations at sufficiently small charges q < 0.5 when linear response holds. At higher ionic charges, the hydration shell contracts, resulting in deviations from linear response in both static and dynamic properties of the electric field produced by water at the ion. Nevertheless, dielectric friction continues to rise in the nonlinear regime, resulting in an overall factor of 3.7 slower diffusion upon placing a single charge q = 1 on the solute. An approximately linear scaling of the inverse diffusion coefficient with the squared ionic charge comes from a mutual compensation between nonlinear solvation and correlations between non-electrostatic and electrostatic forces. Mobility of common electrolyte ions in water is predicted to occur in the regime of nonlinear dielectric friction. [ABSTRACT FROM AUTHOR]

We consider a new class of model systems to study systematically the role of molecular shape in the transport properties of dense liquids. Our model is a liquid binary mixture where both the molecules are non-spherical and characterized by a collection of parameters. Although in the real world most of the molecules are non-spherical, only a limited number of theoretical studies exist on the effects of molecular shapes and hardly any have addressed the validity of the hydrodynamic predictions of rotational and translational diffusion of these shapes in liquids. In this work, we study a model liquid consisting of a mixture of prolate and oblate (80:20 mixture) ellipsoids with interactions governed by a modified Gay-Berne potential for a particular aspect ratio (ratio of the length and diameter of the ellipsoids), at various temperature and pressure conditions. We report calculations of transport properties of this binary mixture by varying temperature over a wide range at a fixed pressure. We find that for the pressure-density conditions studied, there is no signature of any phase separation, except transitions to the crystalline phase at low temperatures and relatively low pressure (the reason we largely confined our studies to high pressure). We find that for our model binary mixture, both stick and slip hydrodynamic predictions break down in a major fashion, for both prolates and oblates and particularly so for rotation. Moreover, prolates and oblates themselves display different dynamical features in the mean square displacement and in orientational time correlation functions. [ABSTRACT FROM AUTHOR]

We examine the separation distance dependence of the hydrophobic force by systematically varying the distance (d) between twowalls. The hydrophobic force exhibits a distance mediated crossover from a liquid-like to a gas-like behavior at around d ~ 12 Å for 1 atm pressure. The distance dependence can be fitted to a bi-exponential form, with the longer distance part displaying a correlation length of 20 Å. In addition, the crossover is found to be accompanied by a divergent-like growth of the local relative number fluctuation of the water molecules confined between the two surfaces. Furthermore, at a fixed separation (d = 20 Å), we observe a pressure induced structural modification of confined water at high pressure. The confined water is found to form an ordered structure at high pressure (10 000 atm) and room temperature, in agreement with the experimental study [ABSTRACT FROM AUTHOR]

Photocatalysis is the most promising and cheap route for water purification. In this work, we demonstrate the degradation of organic pollutants, such as picric acid and methylene blue, by an efficient, reusable Bi2CuO4/BiPO4 heterojunction photocatalyst. The Bi2CuO4/BiPO4 heterojunction was fabricated using a solvothermal method followed by sonication. The Bi2CuO4/BiPO4 heterojunction shows enhanced photocatalytic degradation of picric acid and methylene blue dye under ultraviolet‐visible (UV/Vis) light compared to its individual constituents as well as compared to the previously reported Bi2CuO4‐based photocatalyst. The high photocatalytic activity of the Bi2CuO4/BiPO4 heterojunction can be attributed to the enhanced separation efficiency of the photogenerated electron and hole pairs. The photocatalytic activity of the Bi2CuO4 nanostructures, which is generally weak due to faster recombination of the electron and hole, is enhanced by means of heterojunction formation with BiPO4 nanocrystals. Interestingly, the hydroxyl radical, which was found to be the primary active species, is not generated at the valence band due to thermodynamic constraints. In contrast, experiments carried out under controlled conditions unequivocally confirm that their generation is related to oxygen reduction at the conduction band. Let′s split: A Bi2CuO4/BiPO4 heterojunction shows enhanced photocatalytic degradation of picric acid and methylene blue dye under UV/Vis light compared to its individual constituents and also compared to previously reported Bi2CuO4‐based photocatalysts. The high photocatalytic activity of the Bi2CuO4/BiPO4 heterojunction can be attributed to the enhanced separation efficiency of photogenerated electron and hole pairs. [ABSTRACT FROM AUTHOR]

In this communication we report the observation of intense near infrared (NIR) emissions in the 900 nm to 2000 nm range from colloidal water dispersible lanthanide (Ln3+) doped GdVO4 nanocrystals (Ln = Sm3+, Nd3+, Dy3+, Tm3+, Er3+ and Ho3+). Observing strong NIR emission, particularly from aqueous medium, is a challenge as the luminescence is more prone to non-radiative relaxation. The observed intense NIR emissions from Ln3+-doped GdVO4 nanocrystal ions are attributed to the efficient sensitization of the Ln3+ excited levels via a GdVO4 host matrix. The GdVO4 matrix shows intense and broad absorbance in the ultraviolet (UV) region resulting from the charge transfer from the 2p orbital of oxygen to the d orbital of V5+ ions of the VO4− group. Upon UV excitation, GdVO4 absorbs the light and efficiently transfers the energy to the excited state of the Ln3+ ions, which emit in the NIR region. The calculated energy transfer efficiencies for most of the studied Ln3+ ions are about 90%. In fact, the observed enhancement in the NIR emission intensity varies between 3 (for Sm3+) and 53 fold (Nd3+) compared to direct excitation. The combination of high aqueous stability and intense NIR emission can be advantageous for applications like NIR bioimaging. In addition, these colloidal nanocrystals can easily be incorporated into sol–gel or glass matrices for the fabrication of devices such as optical amplifiers, fiber optics for telecommunications, etc. [ABSTRACT FROM AUTHOR]