Previous studies have shown that Wide-field Infrared Survey Explorer-selected hyperluminous, hot dust-obscured galaxies (Hot DOGs) are powered by highly dust-obscured, possibly Compton-thick active galactic nuclei (AGNs). High obscuration provides us a good chance to study the host morphology of the most luminous AGNs directly. We analyze the host morphology of 18 Hot DOGs at z ∼ 3 using Hubble Space Telescope/WFC3 imaging. We find that Hot DOGs have a high merger fraction (62 ± 14%). By fitting the surface brightness profiles, we find that the distribution of Sérsic indices in our Hot DOG sample peaks around 2, which suggests that most Hot DOGs have transforming morphologies. We also derive the AGN bolometric luminosity (∼1014 L ⊙) of our Hot DOG sample by using IR spectral energy distributions decomposition. The derived merger fraction and AGN bolometric luminosity relation is well consistent with the variability-based model prediction. Both the high merger fraction in an IR-luminous AGN sample and relatively low merger fraction in a UV/optical-selected, unobscured AGN sample can be expected in the merger-driven evolutionary model. Finally, we conclude that Hot DOGs are merger-driven and may represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst-dominated phase to the unobscured QSO phase.

Composition engineering plays an important role in generating novel properties and decreasing the lead (Pb) toxicity for halide perovskite materials. To find out the modulation effect introduced by the composition engineering, namely, B -site co-metal ions, in (MA) 2 AgBi 1−x Sb x Br 6 systems with various Bi/Sb ratios of x = 0, 0.25, 0.75, 1.00, series of theoretical simulations and analyses are carried out. For the (MA) 2 AgBi 1−x Sb x Br 6 systems, the Goldschmidt tolerance factor t and the octahedral factor μ indicate that all samples are in a standard double perovskite structure with alternating AgBr 6 and Bi/SbBr 6 octahedra. The calculated electronic structures show that the band gap of (MA) 2 AgBi 1−x Sb x Br 6 decreases with the increase of Sb content, but the indirect band gaps are maintained for all samples. By analyses of the imaginary part ε 2 (ω) of dielectric function and the absorption spectra, we find that all (MA) 2 AgBi 1−x Sb x Br 6 systems show absorption in the visible-light region. All these results indicate that the composition engineering adopted in this paper is an effective strategy to modulate the optical properties of (MA) 2 AgBi 1−x Sb x Br 6 systems and may open a new way to put it into applications in the fields of solar cells and other optoelectronic devices.

The Cu-modulated lead-free double perovskite Cs 2 AgSbCl 6 shows excellent photoelectric performances. Thus the distribution of Cu dopants inside Cs 2 AgSbCl 6 and the influence induced by them are investigated thoroughly. The variation of charge distribution and then the electronic environment around the Cu dopant are simulated, which support the preferred formation of Cu Ag defect in Cs 2 AgSbCl 6 with a nominal monovalent state. Compared with other Cu-related defects, this configuration introduces the weakest tensile stress around the defects and the slightest distortion of the metal octahedron. Owing to the special Cu Ag defect, the electronic structures of Cs 2 AgSbCl 6 system change, e.g., the bandgap reduces manifestly, ascribing to the predominant contribution from Cu-3d orbitals to the band edges. With the increase of concentration of Cu dopants, the bandgap of Cs 2 AgSbCl 6 decreases further in a monotonic but gentle way, originating from the extra interactions between the Cu-3d orbitals. Therefore, the critical insight to understand the photoelectronic properties of Cs 2 AgSbCl 6 modulated by the Cu dopants is provided.

Taking Cs2NaBiCl6, Cs2AgInCl6 and Cs2AgBiCl6 as examples of Lead-free double perovskites (DPs), we study the photoluminescence (PL) properties of Mn-doped DPs. The electron localization function (ELF) reveals the more ionic...

Cu-doped CsPbBr 3 with strong blue emissions is a potentially ideal material for high-quality light-emitting diode (LED) devices. This study thoroughly analyzes the influence of a Cu dopant on CsPbBr 3 materials through a series of theoretical investigations. Two artificial CsPbBr 3 supercells are constructed, and their electronic properties are analyzed. Additionally, the antibonding nature of the conduction band minimum (CBM) and valance band maximum (VBM) of CsPbBr 3 is elucidated. The results indicate that a Cu dopant can only alter the local lattice around it, not the entire lattice. Moreover, the CBM and VBM deformation potentials of CsPbBr 3 behave differently. Therefore, the energetic shift of VBM is more sensitive to the shrinkage of lattice due to the smaller energy difference between the constituent orbitals, leading to a bandgap reduction with the lattice contraction. This study reveals that the two critical reasons for the increase of bandgap are the contribution of Cu-3d orbitals to the VBM and the localized lattice distortion caused by Cu impurity. Therefore, this work clarifies how Cu impurities improve the blue light emitting performance of CsPbBr 3 systems.