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Generally, tetrahedrally coordinated Ag-based chalcogenides have wider band gaps than their Cu-based counterparts. Recent studies have suggested Cu 3 SbS 4 as the absorber in low-cost and low-toxicity photovoltaic (PV), however its band gap is ∼0.5 eV smaller than the ideal value of ∼1.3 eV. In this work, we investigate Ag 3 SbS 4 by first-principles means, since one can anticipate improved optical properties for this compound. The results indeed demonstrate that enargite Ag 3 SbS 4 is a direct-gap semiconductor with a band gap of 1.38 eV, thus optimal for single-junction solar cells. Furthermore, its carrier effective masses, optical coefficients and spectroscopic limited maximum efficiency are comparable to well-established PV compounds. The compound exhibits also thermodynamical and dynamical stability. Hence, based on the present theoretical study we predict that Ag 3 SbS 4 could be a candidate for absorber in high-efficient thin-film PVs. • Enargite phase is the ground state of Ag 3 SbS 4. • Enargite Ag 3 SbS 4 has a wider band gap than famatinite Cu 3 SbS 4. • Enargite Ag 3 SbS 4 has the suitable band gap to be as PV absorber. • Enargite Ag 3 SbS 4 exhibits thermodynamical and dynamical stability. [ABSTRACT FROM AUTHOR]

The combined quasi-neutral and non-relativistic limit of compressible quantum Euler–Maxwell equations for plasmas is studied in this paper. For well-prepared initial data, it is shown that the smooth solution of compressible quantum Euler–Maxwell equations converges to the smooth solution of incompressible Euler equations by using the modulated energy method. Furthermore, the associated convergence rates are also obtained. [ABSTRACT FROM AUTHOR]

I–III–VI 2 chalcopyrite compounds (I = Cu or Ag; III = Al, Ga, or In; VI = S, Se, or Te), especially sulfides and selelides, were studied as the promising photocathodes for water splitting. In this work, tellurides with a proper band gap [ i.e. CuAlTe 2 (2.06 eV) and AgAlTe 2 (2.27 eV)] had been investigated as the photocathode candidates by our first-principles calculations. Our results show that the band edge positions of AgAlTe 2 straddle the water redox potentials. In combination with the suitable band gap energy and light carrier effective masses along [001]-direction, AgAlTe 2 has the capacity of being a good candidate for water splitting. Moreover, to increase the absorbing ability on visible light, Ga-doping can adjust the band gap of AgAlTe 2 to an appropriate value and remain the reasonable band edge positions of AgAlTe 2 , which is suggested as an effective approach to optimize its electronic structure for water splitting. [ABSTRACT FROM AUTHOR]

Chalcopyrite compounds like Cu(In,Ga)(S,Se) 2 have been widely studied as the absorber for single-junction solar cell. Other wide band gap Chalcopyrite compounds like CuGaS 2 have been utilized as the host of the absorber for intermediate band solar cell (IBSC). Here, a Chalcopyrite compound LiGaTe 2 with a suitable band gap as the host of the absorber for IBSC has been investigated by HSE06 first-principles calculations. Our results revealed that a partially-filled and isolated intermediate band (IB) is generated in the forbidden band gap of LiGaTe 2 after group ⅣA elements (i.e., Si, Ge and Sn) substituting at Ga site and three-photon absorption can be achieved in the doped systems. Combining the suitable IB position induced by Sn-doping and its low formation energy, Sn-doped LiGaTe 2 as a promising candidate has been proposed to be the absorber for IBSC. [ABSTRACT FROM AUTHOR]

Single-photon emitters (SPEs) are attractive as integrated platforms for quantum applications in technologically mature wide-bandgap semiconductors since their stable operation at room temperature or even at high temperatures. In this study, we systematically studied the temperature dependence of the SPE in AlGaN micropillar by experiment. The photoluminescence (PL) spectrum, PL intensity, radiative lifetime and second-order autocorrelation function measurements are investigated over the temperature range from 303 to 373 K. The point defects of AlGaN show strong zero phonon line in the wavelength range of 800–900 nm and highly antibunched photon emission even up to 373 K. Our study reveals a possible mechanism for linewidth broadening in AlGaN SPE at high temperatures. This indicates a possible key for on-chip integration applications based on this material operating at high temperatures. [ABSTRACT FROM AUTHOR]

Uranium (Ⅵ) exists as many species in natural water systems. In the recent years, its contamination to groundwater has been reported more frequently. To investigate the effects of speciation on the removal of uranium, this work investigated the uranium adsorption behaviors of a polyamine-grafted silica composite named SAER at the concentration level of μg/L in the alkaline carbonate solutions with other four resins. Results suggested that the change of uranium speciation had minor effect on the adsorption efficiencies of SAER, except the addition of calcium. This was resulted from that the protonated tetraethylenepentamine had a much higher affinity to the electronegative uranyl-carbonate species, leading to the complete removal of uranium through the simultaneous anion exchange and chemical transformation mechanisms; Column experiments confirmed that merely a small portion of calcium while no magnesium cations were involved in the uranium adsorption in the simulated groundwater. Finally, the integrated removal mechanisms were proposed. Overall, this work demonstrated the feasibility of a novel adsorbent for the effective removal of uranium from different water matrices as well as the mechanisms underlying the interaction of uranium and the functional groups on the adsorbents. Furthermore, it enhanced the understanding of uranium removal under environmentally relevant conditions. Image 1 • Uranium species distribution was calculated by PHREEQC software. • Five resins were compared on the adsorption behaviors under different conditions. • The removal efficiencies of uranium were higher than 99% by SAER. • Integrated adsorption mechanism towards uranium in groundwater was proposed. [ABSTRACT FROM AUTHOR]