KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Author: search.filters.author.Pecharapa, WisanuSubject: search.filters.subject.Local structure

Search Results

Now showing 1 - 2 of 2
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Characterization of Bi-doped FAPbI3 perovskite films investigated by X-ray absorption spectroscopy
    (2025-12-01)
    Wechprasit, Tirapat
    ;
    Bootchanont, Atipong
    ;
    Infahsaeng, Yingyot
    ;
    Wongjom, Poramed
    ;
    Wannapaiboon, Suttipong
    A thorough investigation of perovskite structures formed through doping is essential for advancing the efficiency and stability of perovskite solar cells. In this study, Bi-doped FAPbI<inf>3</inf> perovskite films with varying Bi concentrations (0.5–2%) were fabricated using a spin-coating technique on ITO glass substrates. Then the films’ phase structure, local structure, and optical characteristics were analyzed. X-ray diffraction (XRD) analysis revealed that the pristine FAPbI<inf>3</inf> film exhibited both hexagonal and cubic phases, indicating structural instability. In contrast, Bi-doped FAPbI<inf>3</inf> films predominantly displayed a cubic perovskite structure, with a notable reduction in the XRD peak intensity corresponding to the hexagonal phase. UV–Vis spectroscopy showed that the undoped FAPbI<inf>3</inf> film had an absorption edge in the visible-near infrared range, while Bi-doping caused a redshift, indicating a reduction in the optical band gap. The calculated results show that optical band gaps decrease with increasing Bi, from a value of 1.49 (pure) to 1.43 (2% Bi) eV. X-ray absorption near edge structure (XANES) analysis confirmed the oxidation states of Pb<sup>2+</sup> and Bi<sup>3+</sup> ions across all samples, with Bi ions replacing Pb in the local structure. Photoluminescence (PL) measurements revealed an increased PL intensity with 1% Bi doping (7 10<sup>5</sup>) compared with pristine FAPbI<inf>3</inf> (4.7 10<sup>5</sup>), suggesting a reduction in carrier recombination. These findings demonstrate the potential of Bi-doping to stabilize perovskite structures with improved optoelectronic properties.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Structural and photocatalytic properties and X-ray absorption spectroscopic study of BiVO4 nanoparticles incorporated with Fe synthesized by sonochemical method
    (2022-11-01)
    Wechprasit, Tirapat
    ;
    Bootchanont, Atipong
    ;
    Sailuam, Wutthigrai
    ;
    Wattanawikkam, Chakkaphan
    ;
    Kansaard, Thanaphon
    In this work, Fe-incorporated BiVO<inf>4</inf> nanoparticles with different Fe-loading contents (0–4%) were synthesized via one-step sonochemical process. Crystal structure of all samples was investigated by X-ray diffraction technique (XRD). XRD patterns obviously show the main structure of monoclinic BiVO<inf>4</inf> structure. The secondary phase is found in the form of Fe-based oxide as a hematite Fe<inf>2</inf>O<inf>3</inf> phase at for Fe-loading contents ≥ 2%. Relevant chemical bonding of as-synthesized samples was carried out by Raman spectroscopy indicating the fundamental vibration with various vibration modes of VO<inf>4</inf><sup>3−</sup> tetrahedron and V–O band, respectively. Morphological structure of pure BiVO<inf>4</inf> shows rod-like structure while 1–4%Fe-incorporated BiVO<inf>4</inf> display different morphologies. The chemical compositions and oxidation numbers of all elements of the samples were carried out via X-ray photoelectron spectroscopy (XPS). XPS spectra indicate the existence of all elements on their surface and the oxidation states of all elements are clearly scrutinized. Local structure of all samples was investigated to interrogate the local atomic site of Fe atoms by X-ray absorption spectroscopy (XAS). The normalized Fe K-edge XANES spectra of all samples indicate that the local atomic site of Fe atoms would not replace in local sites of either Bi or V sites in BiVO<inf>4</inf> crystal verified by simulated XANES spectra. However, the specific features of measured XANES spectra of all samples corresponds to the Fe K-edge XANES spectra of Fe<inf>2</inf>O<inf>3</inf> and BiFeO<inf>3</inf> structure suggesting that local structure of all samples are formed to Fe-based oxide between Fe<inf>2</inf>O<inf>3</inf> and BiFeO<inf>3</inf> structure. Fitting EXAFS spectra of 1–4%Fe-incorporated were practically conducted by artemis program with Fe<inf>2</inf>O<inf>3</inf> and BiFeO<inf>3</inf> used as structural models to identify local atomic environment of Fe atoms. Results show agreeable fitting with their structural models and reveal pertinent information of localization of Fe atoms. Optical properties of the samples were analyzed by UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). DRS results exhibit the absorption edge in visible range of all samples. Meanwhile, influence of Fe loading contents into pure BiVO<inf>4</inf> displays to confirm the red-shift on the absorption edge in visible range to higher wavelength, which suggests the lower optical band gap of pure BiVO<inf>4</inf>. The optimized photocatalytic degradation of RhB was performed by 4%Fe–BiVO<inf>4</inf> with 82% decolorization under visible-light irradiation within 10 min and exhibited rate constant at 0.150 min<sup>−1</sup>.