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In the present paper, the effect of different bent angles on structural stability, electronic structure, and optical properties of Na absorbed borophene system is investigated using the density functional theory. The structure of the borophene was almost unchanged and the planar structure was not disrupted after the adsorption of a Na atom. Directly above the bottom B–B bonds is considered as the optimal adsorption position of single. The stability of the Na adsorbed borophene system can be decreased under the condition of different bent angles. The adsorption of Na atoms changes the energy band structure of the intrinsic borophene according to the calculation results of energy band structure and density of states, which resulting the conduction band contains more impurities. The 2p orbital of Na and the 3p orbital of B hybridize between −4 eV and 6 eV. Bending deformation gives rise to the electron transfer between Na atoms and B atoms. In terms of optical properties, the bending deformation improves the absorption of infrared light and the catalytic activity of light in the adsorbed system. • The structure of the borophene was almost unchanged and the planar structure was not disrupted after the adsorption of a Na atom. • The stability of the Na adsorbed borophene system can be decreased under the condition of different bent angles. • The adsorption of Na atoms changes the energy band structure of the intrinsic borophene so that its conduction band contains more impurities. • The bending deformation improves the absorption of infrared light and the catalytic activity of light in the adsorbed system. [ABSTRACT FROM AUTHOR]

SrAl 2 O 4 :Eu 3+ down-conversion (DC) nanocrystals were synthesized by a sol–gel method and then doped in TiO 2 as a photoanode in dye-sensitized solar cells (DSSCs). Differential thermal analysis, fourier transform infrared spectroscopy, X-ray diffraction and Brunauer–Emmet–Teller analysis confirmed the formation of SrAl 2 O 4 :Eu 3+ nanocrystals with diameters of ∼47 nm, pore size of ∼25 nm, sintering temperature of 1300 °C. The photoluminescence and UV–vis absorption spectra of the SrAl 2 O 4 :Eu 3+ revealed a DC from ultraviolet light to visible light which matched the strong absorbing region of the N719 dye. The photoelectric conversion efficiency of the DSSCs with a TiO 2 photoanode doped with 3 wt% SrAl 2 O 4 :Eu 3+ was 20% higher than that with a pure TiO 2 photoanode. This phenomenon could be mainly explained by SrAl 2 O 4 :Eu 3+ nanocrystals’ ability of DC and increased the short-circuit current density. It could be minorly due to the p-type doping effect and slightly improved the open-circuit voltage. [ABSTRACT FROM AUTHOR]