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Study of BiFeO3 thin film obtained by a simple chemical method for the heterojunction-type solar cell design
摘要： Polycrystalline BiFeO3 (BFO) films of different thickness were synthesized by a 2-methoxyethanol (acid)-free simple chemical method. A rhombohedral-type pure phase with a crystallite size less than 18.8 nm was obtained. SEM micrographs showed that BFO has a flat and homogeneous morphology when it was deposited on different semiconductor substrates (ZnO, Ni doped ZnO, and CdS). The highest roughness value (8.6 nm) was observed when BFO was deposited on CdS. The optical response showed that the optical band gap slightly changes as thickness increases. The photovoltaic response of the BFO film was assessed employing different solar cell architectures (p-BFO-n and BFO-n). The results showed that the solar cell based on the Ag/PbS/BFO/CdS/FTO/glass structure presented a short-circuit current density of JSC ? 239:6 mA=cm2 and a power conversion efficiency of h ? 7:65 (cid:2) 10(cid:3)3 %. Photoelectrochemical and ferroelectric measurements were employed to explain the photovoltaic response.
关键词： Mott-Schottky,XPS,PFM,BiFeO3 thin films
更新于2025-09-23 15:21:01
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Scalable Route toward Superior Photoresponse of UV-Laser-Treated TiO <sub/>2</sub> Nanotubes
摘要： Titanium dioxide nanotubes gain considerable attention as a photoactive material due to chemical stability, photocorrosion resistance, or low-cost manufacturing method. This work presents scalable pulsed laser modification of TiO2 nanotubes resulting in enhanced photoactivity in a system equipped with a motorized table, which allows for modifications of both precisely selected and any-large sample area. Images obtained from scanning electron microscopy along with Raman and UV?vis spectra of laser-treated samples in a good agreement indicate the presence of additional laser-induced shallow states within band gap via degradation of crystalline structure. However, X-ray photoelectron spectroscopy spectra revealed no change of chemical nature of the modified sample surface. Photoelectrochemical measurements demonstrate superior photoresponse of laser-treated samples up to 1.45-fold for an energy beam fluence of 40 mJ/cm2 compared to that of calcined one. According to the obtained results, optimal processing parameters were captured. Mott?Schottky analysis obtained from impedance measurements indicates an enormous (over an order of magnitude) increase of donor density along with a +0.74 V positive shift of flat band potential. Such changes in electronic structure are most likely responsible for enhanced photoactivity. Thus, the elaborated method of laser nanostructuring can be successfully employed to the large-scale modification of titania nanotubes resulting in their superior photoactivity. According to that, the results of our work provide a contribution to wider applications of materials based on titania nanotubes.
关键词： nanotubes,titanium dioxide,Mott?Schottky analysis,laser modification
更新于2025-09-12 10:27:22
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Vacuum evaporated FTO/(Cu, Ag)2ZnSnSe4 thin films and its electrochemical analysis
摘要： Cu2ZnSnSe4 and Ag2ZnSnSe4 thin films were deposited on FTO substrates by the thermal evaporation method and the films were then annealed at 300?C for 2 hrs. The XRD analysis confirms the formation of tetragonal structure for both CZTSe and AZTSe thin films. The introduction of Ag instead of Cu is confirmed by the major crystalline peak (112) shift towards lower angle 2θ=26.1? (for AZTSe). In the Raman spectra, the noticeable vibrations at 186 cm-1 and 183 cm-1 confirm the formation of CZTSe and AZTSe thin films. The Raman technique also found the presence of SnSe as a secondary phase. By comparing the optical spectra, the AZTSe film has higher absorption in the visible region than the CZTSe thin films which is attributed to the surface plasmon resonance of Ag. AFM images show a pyramidal structure for both CZTSe and AZTSe films. The Mott-Schottky plot shows p-type conductivity for FTO/CZTSe while there is n-type conductivity for a FTO/AZTSe thin film. The variation in the conductivity is due to replacing Cu with Ag. Photoelectrochemical cell (PEC) performance was employed in the presence of a polysulfide electrode by a standard three-electrode system. By comparing the value of Voc, the AZTSe film shows higher VOC than CZTSe films which is important for photovoltaic applications. The Photoconversion efficiency (PCE) is measured to be 0.31 % for FTO/AZTSe thin films, while it is low about 0.29% for FTO/CZTSe. The impedance plot shows the semicircular nature for both the FTO/CZTSe and FTO/AZTSe films.
关键词： Mott-schottky,Electrochemical Impedance,Cu2ZnSnSe4,Photoelectrochemical cell,Ag2ZnSnSe4
更新于2025-09-09 09:28:46
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Gold nanoparticle/nickel oxide/poly(pyrrole-N-propionic acid) hybrid multilayer film: Electrochemical study and its application in biosensing
摘要： The present study describes the fabrication of Indium Tin Oxide /gold nanoparticles/nickel oxide/poly(Pyrrole-N-propionic acid) (ITO/GNPs/NiO/poly(PPA)) multilayered film, and its modification with Tyrosinase (Ty). The ITO/GNPs/NiO/poly(PPA) electrode was fabricated by sequential electrochemical assembly onto ITO substrate which electrochemical deposition provides a facile, inexpensive technique for synthesis of multilayered film within the adherent morphology with controllable film thickness. Cyclic voltammetry (CV), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), scanning electron microcopy (SEM), and atomic force microcopy (AFM) were used to characterize the film assembly processes. The properties of a semiconductor/electrolyte interface were investigated based on the Mott–Schottky (M-S) approach for the modified electrodes, with the flat band potential (EFB) according to the potential intercept and the carrier density (ND) according to the linear slopes. The ND and EFB of ITO/GNPs/NiO/poly(PPA) were obtained as 2.48·1021 cm–3 and 0.26 V, respectively. Tyrosinase was immobilized using carbodiimide coupling reaction. The bioelectrode was characterized by FTIR-ATR, SEM, AFM, electrochemical impedance spectroscopy (EIS). A Randles equivalent circuit was introduced for modeling the performance of impedimetric biosensing for the detection of the dopamine (DP) and the interface of bioelectrode/electrolyte. The EIS of the ITO/GNPs/NiO/poly(PPA)-Ty exhibited significant changes in the charge transfer resistance (RCT) value toward the detection of dopamine over a linear range of 80 μM to 0.2 mM with a limit of detection (LOD) of 5.46 μM.
关键词： tyrosinase,poly(pyrrole-N-propionic acid),polymer composites,Mott–Schottky,dopamine
更新于2025-09-09 09:28:46