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Post-annealing effects on the structural and optical properties of nickel vanadate thin films.
(2026-05-15)
Nedkun, Piyanooch
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Sangsai, Phannita
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Wongrat, Ekasiddh
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Chaiworn, Panupat
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Tubtimtae, Auttasit
Abstract This research gap is to understand the post-annealing-temperature-dependent structural transition and defect-mediated optical tuning in NiV₂O₆ thin films deposited using a spin-coating technique. By systematically correlating phase evolution, oxygen vacancy formation, and band gap modulation. The as-prepared thin films were annealed at 200 °C, 300 °C, 400 °C, and 500 °C. The annealing temperature of 400 °C was found for an amorphous structure with the band gap of 2.38 eV, which within an appropriate band gap of ∼ 2.3–2.6 eV for photoelectrochemical and electrochromic applications. Tuning of improved crystallinity with structural rearrangement and a lower band gap of 2.10 eV were obtained at 500 °C, which induced the diffusion of oxygen atoms and led to the formation of oxygen vacancies. This provides a clear processing–structure–optical property correlation and offers a simple-thermal route for band gap engineering without additional doping for enhancing the optical efficiency in solar absorber, optoelectronic, and photonic applications, particularly in broadband optical devices.
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WO3:AgInS2 quantum dot electron transport layers in enhanced perovskite solar cells
(2023-04-14)
Seriwattanachai, Chaowaphat
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Kaewprajak, Anusit
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Sukgorn, Nuttaya
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Kumnorkaew, Pisist
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Nukeaw, Jiti
The development of the electron transport layers (ETL) was crucially important for the improvement of charge extraction and transportation in perovskite solar cells (PSCs). Here, dual electron transport layers of TiO<inf>2</inf> and WO<inf>3</inf> mixed with different sizes of AgInS<inf>2</inf> quantum dots (TiO<inf>2</inf>/WO<inf>3</inf>:AgInS<inf>2</inf> QDs) were fabricated for planar perovskite solar cells. The peak intensity of the photoluminescence (PL) of the synthesized AgInS<inf>2</inf> QDs were redshifted from 554 to 655 nm with an increased radius of AgInS<inf>2</inf> QDs from 3.82 ± 0.52 to 7.78 ± 1.37 nm. The PL intensity of the perovskite film on TiO<inf>2</inf>/WO<inf>3</inf>:AgInS<inf>2</inf> QDs was quenched by the addition of AgInS<inf>2</inf> QDs. The improved device stability was probably caused by the WO<inf>3</inf>:AgInS<inf>2</inf> QDs layer protecting the interface of perovskite layers from direct contact with TiO<inf>2</inf> to prevent UV decomposing. Therefore, the TiO<inf>2</inf>/WO<inf>3</inf>:AgInS<inf>2</inf> QDs as electron transport layers promoted the perovskite solar cell performance and enhanced the long-term stability. Graphical abstract: [Figure not available: see fulltext.].
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Structural, optical and electrical properties of Sb-doped ZnO/ZnO homojunction thin film structures prepared by sol-gel based coating process under nitrogen annealing atmosphere
(2022-09-01)
Sinornate, Wuttichai
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Mimura, Hidenori
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Pecharapa, Wisanu
This investigation focuses on structural, optical and electrical properties of Sb-doped/undoped ZnO double layer structure annealed in nitrogen atmosphere. The double layer film was prepared by sol-gel spin coating technique onto ITO substrate then annealed in nitrogen atmosphere. The crystal structure demonstrates hexagonal ZnO without phase impurity. The deterioration in the crystal structure due to Sb is incorporated in ZnO lattice and nitrogen annealing atmosphere and the decrease in diffraction intensity due to the different thickness of the ZnO film. The existence of Sb atom in the doped ZnO film is confirmed by depth profile measurement. The transmittance spectra exhibit high transparency with interference fringe and the photoluminescence spectrum shows the near-band-edge emission of ZnO without any emission in the visible region. The electrical properties demonstrate diode characteristics and photocurrent under dark and UV irradiation, respectively.
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Structural, optical, and electrical properties via two simple routes for the synthesis of multi-phase potassium antimony oxide thin films
(2022-07-15)
Homcheunjit, Ratchaneekorn
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Pluengphon, Prayoonsak
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Tubtimtae, Auttasit
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Teesetsopon, Pichanan
Multi-phase ternary oxide glass thin films of potassium antimony oxide were synthesized via dip coating (DC) and spray pyrolysis (SP) methods. The growth of thin film was conducted on a non-conductive borosilicate glass substrate. Surface morphology was investigated and showed different characteristics. X-ray diffraction (XRD) analysis revealed the peaks corresponded to the monoclinic KSb<inf>3</inf>O<inf>5</inf> and K<inf>2</inf>Sb<inf>4</inf>O<inf>11</inf> phases. The structural parameter analysis shows that the lower values of micro strain (ε), dislocation density (δ), and stacking fault probability (SF) with higher number (N) of particle in the multi-phase thin film for the spray pyrolysis method confirm slightly larger crystallite size, less crystal imperfection, and less structural disorder. The lower average transmission, absorption, and extinction coefficients resulted to higher refractive index, permittivity, and electrical susceptibility for the sample synthesized by a spray pyrolysis method. In addition, the average energy band gap values (E<inf>g</inf>) of 3.57 and 3.60 eV were obtained for the dip coating and spray pyrolysis methods, respectively. However, the lower R<inf>s</inf> (14.69 × 10<sup>7</sup> Ω/sq.) with higher σ<inf>h</inf> (85.09 S/cm) and the FOM<inf>(H-HR)</inf> (0.183 Ω<sup>-1</sup>) of the multi-phase K–Sb–O thin film for the dip coating method were obtained may be due to more interconnections generated at the interface and there are less residual on the surface of thin film.
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Influence of processing parameters on the hydrogen storage properties of dip coated lithium alanate thin films
(2021-05-19)
Choawarot, Choosak
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Siriwongrungson, Vilailuck
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Hongrapipat, Janjira
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Pang, Shusheng
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Messner, Michael
The complex metal hydride materials have been researched and reported as an effective hydrogen storage material with the gravimetric hydrogen storage capacity of around 5-7 wt%. In this paper, the 20 mg/cm3 of lithium alanate solution prepared at 4 degree C and 25 degree C were dip coated on glass substrate. The post-annealing time was varied at 0 s, 1800 s and 3600 s. Phase and grain size were investigated using the X-ray powder diffraction. The hydrogen storage capacity and hydrogen desorption temperature were analyzed using thermogravimetric analysis. The lithium aluminium hydroxide hydrate and lithium hexahydroaluminate were observed on the deposited lithium alanate thin films when using the lithium alanate solution prepared at 4 degree C while only the lithium hexahydroaluminate was detected on the deposited lithium alanate thin films when the lithium alanate solution was prepared at 25 degree C. It was observed that the deposited lithium alanate thin films with lithium aluminium hydroxide hydrate have lower hydrogen storage capacity than the lithium alanate thin films without lithium aluminium hydroxide hydrate even the lithium alanate thin films with lithium aluminium hydroxide hydrate have smaller grain size. The hydrogen storage capacity and hydrogen desorption temperature of the deposited lithium alanate thin films were improved with longer annealing time.

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