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Multi-doped bismuth ferrite thin films with enhanced multiferroic properties
摘要： Thin films of multi-doped bismuth ferrite, Bi0.97?xLaxSr0.03Fe0.94Mn0.04Co0.02O3 (BLxSFMC, x = 0.00–0.18), are synthesized on a fluorine-doped tin oxide (FTO)/glass substrate. The structure and multiferroic properties of the film samples are characterized and tested. The results indicate that on doping, the structure of the BLxSFMC film changes has been changed. The concentrations of both oxygen vacancies and Fe2+ are decreased. The BL0.18SFMC thin film exhibits Ohmic conduction, which reduces the influence of the built-in electric field Ebi of the space-charge region at the interface between an Au electrode and the BLxSFMC during polarization. The BL0.18SFMC thin film also exhibits enhanced ferroelectric properties than the undoped film, with a higher residual polarization of 188 μC/cm2 and a higher squareness ratio of 1.21. Meanwhile, the reduced number of oxygen vacancies also reduces the Fe2+/Fe3+ ratio, thereby enhancing the Dzyaloshinskii–Moriya interaction of Fe–O–Fe bonds, and so the BL0.18SFMC thin film exhibits enhanced ferromagnetism, with a saturation magnetization of Ms ≈ 3.94 emu/cm3. Thus, multi-ion doping can improve both the ferroelectric and ferromagnetic properties of BLxSFMC thin films.
关键词： Ohmic conduction,built-in electric field,oxygen vacancy,multiferroic
更新于2025-11-14 17:28:48
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Modulated charge transport characteristics in solution-processed UV photodetector by incorporating localized built-in electric field
摘要： The application of ZnO in the field of ultraviolet (UV) photodetectors is hindered by the lower responsivity, which is attributed to the strong band-to-band direct recombination caused by its large exciton binding energy and defect-assisted charge recombination related with the presence of defect states. Here, a solution-processed ZnO:Poly[N-90-heptadecanyl-2,7- carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT) composite photosensitive layer is employed to overcome these shortcomings. By incorporating PCDTBT, the localized built-in electric field can be constructed, which effectively facilitates the photogenerated exciton dissociation in annealing-free ZnO layer. Meanwhile, the formed depletion region in dark reduces the majority carrier density, thus decreasing the dark current of the photodetector. Furthermore, the absorption spectrum of PCDTBT perfectly overlaps the photoluminescence of ZnO, which is beneficial for the reutilization of carrier recombination energy by fluorescence resonance energy transfer. This study reveals that the charge recombination loss in ZnO limits the photoresponse, and points a direction to improve the light detection capacity of UV photodetectors.
关键词： ZnO,UV photodetector,Solution-processed,PCDTBT,Built-in electric field
更新于2025-11-14 15:27:09
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Enhanced photo-catalytic performance by effective electron-hole separation for MoS2 inlaying in g-C3N4 hetero-junction
摘要： The MoS2/g-C3N4 heterojunction composite (marked as MoS2/g-C3N4-H) was successfully prepared via calcining the melamine coated MoS2 nano-sphere, where the thin g-C3N4 nano-sheets were tightly grown on the surface of MoS2 nano-sphere to form MoS2 inlaying in g-C3N4 heterostructure. The detailed charge transfer mechanism was discussed by combining theoretical calculation and experiments, in which the intrinsic cause of photo-generated charge separation and transfer was determined as the directional built-in electric field driven by different Fermi levels of MoS2 and g-C3N4. Comparatively, the enhanced photo-catalytic performance and stability of the sample were assessed by degrading the Rhodamine (RhB) and reducing the Dichromate (Cr6+) solutions under the irradiation of the simulated sunlight, which could be attributed to the widened spectral absorption range and improved electron-hole separation rate. Based on above results, the photo-catalytic mechanism involving redox reactions was also clearly proposed.
关键词： MoS2,Built-in electric field,Photocatalyst,Heterojunction,g-C3N4
更新于2025-09-23 15:23:52
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Effect of Horizontal p-n Junction on Optoelectronics Characteristics in InGaN-Based Light-Emitting Diodes with V-shaped Pits
摘要： Two InGaN-based light-emitting diodes (LEDs) with and without pre-layer were prepared, and both had a similar multi-quantum well (MQW) structure with four green QWs near n-GaN and one blue QW close to p-GaN. The pre-layer established large V-shaped pits in MQWs. In addition to the regular vertical p-n junction along c-axis, a kind of horizontal p-n junction created by n-type MQWs and p-GaN filled in V-shaped pits was introduced. And the effect of the horizontal p-n junction on optoelectronics characteristics, including photoluminescence, electroluminescence, and ??-??, were discussed. The horizontal p-n junction creates a strong horizontal built-in electric field which can effectively separate the photogenerated carriers in the QW close to p-GaN, leading to the absence of photoluminescence from the QW close to p-GaN. The horizontal p-n junction also provides a path for hole injection, which changes the turn-on order of QW, and reduces the voltage of the LED with large V-shaped pits. These results suggest a new thought of analyzing and designing InGaN-based LEDs with V-shaped pits.
关键词： light-emitting diode,V-shaped pit,indium gallium nitride,built-in electric field
更新于2025-09-23 15:19:57
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Interfacial coupling effects in g-C3N4/SrTiO3 nanocomposites with enhanced H2 evolution under visible light irradiation
摘要： The g-C3N4/SrTiO3 nanocomposite is an important material in photocatalysis, but little attention has been paid to their interfacial interaction in photocatalytic reaction. Herein, we prepare the g-C3N4/SrTiO3 nanocomposites via a two-step mechanically milling and calcination process. The composite exhibited the highest H2 evolution activity superior to that of the pure g-C3N4 and SrTiO3 in the visible light. The results of UV-vis DRS, PL and photoelectrochemical measurements demonstrated that g-C3N4/SrTiO3 exhibited more visible light adsorption and faster photo-generated charge transfer. Furthermore, with the help of a strong built-in electric field presenting in the g-C3N4/SrTiO3 interface, the photo-generated electrons flow to the SrTiO3 from g-C3N4, leading to the highly-efficient electron separation and more H2O molecules photo-reduction to H2. This work explicates the significant role of built-in electric field in H2 evolution on g-C3N4/SrTiO3 photocatalyst.
关键词： built-in electric field,g-C3N4,visible light,H2 evolution,SrTiO3
更新于2025-09-19 17:15:36
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Enhanced photocatalytic hydrogen evolution of?CdWO4 through polar organic molecule modification
摘要： In this work, a polar molecule 4-mercaptobenzoic acid (4-MBA) is anchored on the surface of CdWO4 by forming CdeS and WeS bond. Photocatalytic hydrogen evolution is significantly enhanced (about 3.41 times) after the modification. The reason is due to the modification of 4-MBA, which results in a polar surface and built-in electric field. The polar surface is confirmed by the steady state and time-resolved PL spectra, Voc and SHG results.
关键词： CdWO4,Photocatalytic hydrogen evolution,4-mercaptobenzoic acid,Surface modification,Built-in electric field
更新于2025-09-19 17:15:36
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Interband optical absorption in wurtzite GaN/InxGa1?xN/GaN spherical quantum dots with built-in electric field
摘要： Based on the principle of density matrix and the finite element method, the interband optical absorption between the electron and hole has been investigated in a wurtzite GaN/InxGa1?xN/GaN spherical core–shell quantum dot (CSQD) including a strong built-in electric field (BEF). We have studied the effects of the size and the ternary mixed crystal on the optical absorption coefficients (ACs) and refraction index changes (RICs). The results indicate that the absorption peaks of ACs and RICs decrease rapidly, and show a redshift with the increase of the component x. It is also found that the absorption peaks of ACs and RICs reduce obviously and depend on the core radius and the well width. When the core radius increases, the positions of the maximum ACs and RICs show a blueshift. At the same time, it presents a redshift when the well width increases. Particularly, the influence of the well width is much stronger than the core radius in the wurtzite GaN/InxGa1?xN/GaN spherical CSQDs. We hope that these results could provide guidance on both theoretical and experimental study related to the optical properties of spherical CSQDs.
关键词： Core–shell quantum dot,built-in electric field,optical property,ternary mixed crystal effect
更新于2025-09-12 10:27:22