•As-cut mc-Si wafer can be isotropically etched by a two-step alkali-etch process.•Flat wafer surface benefits homogenous nanostructure and cell's performance.•Mean efficiency of N-DRE Bmc-Si cells reach 18.63%, 0.6% higher than normal ones.•Isc and Voc voltage were improved simultaneously in N-DRE Bmc-Si solar cells.•High Voc of N-DRE Bmc-Si solar cells is contributed to small dark current I0.Alkali solutions are not suitable for texturing multi-crystalline silicon (mc-Si) wafer due to the anisotropic etching. In this study, a two-step alkali-etch process is developed to form a flat surface on the wafer, which can be quickly and nearly isotropically etched by immersion in a sodium hydroxide solution, followed by a sodium hydroxide-sodium hypochlorite solution. The etching process leads to the formation of homogenous nanostructure, thereby improving the cell's repeatability and performance by simultaneously increasing its short-circuit current and open-circuit voltage.

TiO2 thin films were grown on solar-grade (SoG) multicrystalline silicon (mc-Si) wafers with different multiscale structures by using a liquid phase deposition (LPD) method. It was found that due to the carrier injection from mc-Si wafers, the photocatalytic activity of the TiO2 films could be expanded from the ultraviolet to the visible light region. In addition, further enhanced visible light photocatalytic properties could be achieved by introducing a nano-texture and p–n junction into the mc-Si wafer, which was ascribed to the excellent light trapping and strong carrier separating properties. Our results suggest that density-graded nanostructures applied to the TiO2 photocatalyst can enhance optical absorption, benefit carrier separation, and improve photocatalytic activity.

A facile sol–gel approach with a fixed calcination temperature is developed to prepare BiFeO3 (BFO) nanoparticles, and the gel-drying temperature is adjusted to control the appearance of a γ-Fe2O3 parasitic phase. The room temperature ferromagnetism of the samples is strongly dependent on the gel-drying temperature. When the gel-drying temperature increases from 80 to 140 °C, the saturated magnetization of the corresponding samples jumps from 0.22 emu g−1 to 1.2 emu g−1, allowing the nanoparticles to be magnetically separated in solution. From examination by transmission electron microscopy and X-ray photoelectron spectroscopy, it is confirmed that the γ-Fe2O3 parasitic phase is nucleated during the gel-drying process under high temperatures above 120 °C, and remains in the subsequent annealing process, resulting in the anomalous enhanced magnetization. Comparing with pure BFO nanoparticles prepared under low gel-drying temperature, the BFO/γ-Fe2O3 samples exhibit significantly increased visible-light photocatalytic ability towards rhodamine B. The formation of a heterojunction structure between the BFO and γ-Fe2O3 phases is proposed to be responsible for the enhanced photocatalytic activity. Further enhanced photocatalytic activity is obtained in this study when adding a small amount of H2O2 during photocatalysis, indicating the samples have photo-Fenton-like catalytic activity.

BiFeO3 (BFO) is of considerable interest because of its potential applications in the design of devices combining magnetic, electronic, and optical functionalities. Effects of the Gd dopant on the structural, photocatalytic activity, and ferromagnetic properties of BFO nanoparticles have been studied. X-ray diffraction and Raman spectra results of Bi1−xGdxFeO3 (BGFOx, x = 0, 0.05, 0.1, and 0.15) reflect that the crystal structure of the samples remain stable for x < 0.1, while compositional-driven phase transition from rhombohedral to orthorhombic is observed at x = 0.1. The photocatalytic activity to decompose Rhodamine-B under visible-light illumination increases in BGFOx as x increases from zero to 0.1 and then decreases for x = 0.15. The maximum in photocatalytic activity near the phase boundary of x = 0.1 is associated with the changing of the polar behavior of the nanoparticles. Comparing with the linear magnetization−magnetic field (M−H) relation in pure BFO nanoparticles, obvious M−H loops can be observed in the doped samples, which are ascribed to the distorted spin cycloid and magnetically active characteristic of Gd3+ ions.

The structural, electrical, luminescent, and magnetic properties of Eu3+-doped Ba0.77Ca0.23TiO3 (BCT23:Eu) ceramics were investigated in this paper. Three different incorporation mechanisms of Eu3+ were realized in BCT23 by considering different charge compensation mechanisms: (i) Ca site substitution with Ca vacancy compensation; (ii) Ti site substitution with O vacancy compensation; (iii) simultaneous substitution at both Ca and Ti sites with self-compensation. Besides the evident ferroelectric properties, the BCT23:Eu ceramics showed the photoluminescence and paramagnetic properties, implying that they can be considered as the multifunctional materials. Both the electric and luminescent properties were sensitive to the Eu doping concentrations and positions, due to the variations of the microstructures and different charge compensation mechanisms.

The CaCu3Ti4O12/SiO2/CaCu3Ti4O12 (CCTO/SiO2/CCTO) multilayered films were prepared on Pt/Ti/SiO2/Si substrates by pulsed laser deposition method. It has been demonstrated that the dielectric loss and the leakage current density were significantly reduced with the increase of the SiO2 layer thickness, accompanied with a decrease of the dielectric constant. The CCTO film with a 20 nm SiO2 layer showed a dielectric loss of 0.065 at 100 kHz and the leakage current density of 6×10−7 A/cm2 at 100 kV/cm, which were much lower than those of the single layer CCTO films. The improvement of the electric properties is ascribed to two reasons: one is the improved crystallinity; the other is the reduced free carriers in the multilayered films.

TiO2 thin films were grown on solar-grade (SoG) multicrystalline silicon (mc-Si) wafers with different multiscale structures by using a liquid phase deposition (LPD) method. It was found that due to the carrier injection from mc-Si wafers, the photocatalytic activity of the TiO2 films could be expanded from the ultraviolet to the visible light region. In addition, further enhanced visible light photocatalytic properties could be achieved by introducing a nano-texture and p–n junction into the mc-Si wafer, which was ascribed to the excellent light trapping and strong carrier separating properties. Our results suggest that density-graded nanostructures applied to the TiO2 photocatalyst can enhance optical absorption, benefit carrier separation, and improve photocatalytic activity.

A facile sol–gel approach with a fixed calcination temperature is developed to prepare BiFeO3 (BFO) nanoparticles, and the gel-drying temperature is adjusted to control the appearance of a γ-Fe2O3 parasitic phase. The room temperature ferromagnetism of the samples is strongly dependent on the gel-drying temperature. When the gel-drying temperature increases from 80 to 140 °C, the saturated magnetization of the corresponding samples jumps from 0.22 emu g−1 to 1.2 emu g−1, allowing the nanoparticles to be magnetically separated in solution. From examination by transmission electron microscopy and X-ray photoelectron spectroscopy, it is confirmed that the γ-Fe2O3 parasitic phase is nucleated during the gel-drying process under high temperatures above 120 °C, and remains in the subsequent annealing process, resulting in the anomalous enhanced magnetization. Comparing with pure BFO nanoparticles prepared under low gel-drying temperature, the BFO/γ-Fe2O3 samples exhibit significantly increased visible-light photocatalytic ability towards rhodamine B. The formation of a heterojunction structure between the BFO and γ-Fe2O3 phases is proposed to be responsible for the enhanced photocatalytic activity. Further enhanced photocatalytic activity is obtained in this study when adding a small amount of H2O2 during photocatalysis, indicating the samples have photo-Fenton-like catalytic activity.