Kayunkid, Navaphun

Preferred name

Kayunkid, Navaphun

Alternative Name

Kayunkid, N.

Kayunkid, Nawapun

Main Affiliation

Integrated Innovative Technology

navaphun.ka@kmitl.ac.th

Now showing 1 - 10 of 45

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Metal Oxide Nanostructures Enhanced Microfluidic Platform for Efficient and Sensitive Immunofluorescence Detection of Dengue Virus
(2023-11-01)
Pormrungruang, Pareesa
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Phanthanawiboon, Supranee
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Jessadaluk, Sukittaya
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Larpthavee, Preeda
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Thaosing, Jiraphon
Rapid and sensitive detection of Dengue virus remains a critical challenge in global public health. This study presents the development and evaluation of a Zinc Oxide nanorod (ZnO NR)-surface-integrated microfluidic platform for the early detection of Dengue virus. Utilizing a seed-assisted hydrothermal synthesis method, high-purity ZnO NRs were synthesized, characterized by their hexagonal wurtzite structure and a high surface-to-volume ratio, offering abundant binding sites for bioconjugation. Further, a comparative analysis demonstrated that the ZnO NR substrate outperformed traditional bare glass substrates in functionalization efficiency with 4G2 monoclonal antibody (mAb). Subsequent optimization of the functionalization process identified 4% (3-Glycidyloxypropyl)trimethoxysilane (GPTMS) as the most effective surface modifier. The integration of this substrate within a herringbone-structured microfluidic platform resulted in a robust device for immunofluorescence detection of DENV-3. The limit of detection (LOD) for DENV-3 was observed to be as low as 3.1 × 10−4 ng/mL, highlighting the remarkable sensitivity of the ZnO NR-integrated microfluidic device. This study emphasizes the potential of ZnO NRs and the developed microfluidic platform for the early detection of DENV-3, with possible expansion to other biological targets, hence paving the way for enhanced public health responses and improved disease management strategies.
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An unconventional blade coating for low-cost fabrication of PCDTBT: PC70BM polymer and CH3NH3PbIxCl3-x perovskite solar cells
(2021-04-01)
Kaewprajak, Anusit
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Kumnorkaew, Pisist
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Lohawet, Khathawut
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Duong, Binh
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Chonsut, Teantong
A low-cost and unconventional blade coating technique, called convective deposition, has been introduced for PCDTBT:PC<inf>70</inf>BM polymer and CH<inf>3</inf>NH<inf>3</inf>PbI<inf>x</inf>Cl<inf>3-x</inf> perovskite solar cell fabrication. With the new technique, only 10–20 microliter droplets per one square inch substrate were used to deposit hole transporting material, as well as photoactive and electron transporting materials, sequentially to create a p-i-n structure solar cell. Thin film deposition and solar cell fabrication from the standard spin coating and the convective deposition were compared. Smaller and better distribution of PC<inf>70</inf>BM domain in the PCDTBT:PC<inf>70</inf>BM film was observed in the film prepared by the convective deposition. Unlike the conventional doctor-blade coating or the spin coating, the film thickness can simply be adjusted by the convective deposition speed. The highest averaged power conversion efficiency (PCE) of 6.34% was obtained from the polymer solar cell prepared by the convective deposition at the coating speed of 750 μm/s compared to 5.60% PCE from the spin coating at the speed of 2500 rpm. For perovskite solar cell, a heating stage was used during the convective deposition of perovskite ink, 10.61% PCE was achieved with the stage temperature of 70 °C and the 2500 μm/s deposition speed. Layer-by-layer deposition with the convective deposition used in this study offers benefits over the standard spin coating by reducing amount of material consumption in the fabrication process and being suitable for low-cost fabrication of other solution-based optoelectronic devices.
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Enhancing Perovskite Thin Films with Butylammonium Iodide-Lead-Tetrahydrofuran: Surface Healing and 2D Formation in Annealing-Free Single-Crystal Films for Solar Cell Applications
(2024-04-01)
Azad, Farhad
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Supasai, Thidarat
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Yaro, Annafi Ado
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Soe, Kay Thi
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Thongprong, Non
We demonstrate a functional method to achieve surface passivation and construct a two-dimensional (2D) layer on a three-dimensional (3D) perovskite, eliminating the need for subsequent annealing steps. A key process is the integration of a single methylammonium lead iodide (MAPbI<inf>3</inf>) crystal with butylammonium iodide (BAI) in tetrahydrofuran. Density functional theory calculations reveal that the synergy between BA+ cations and Pb-I octahedral structures enables the formation of a distinct 2D layered framework. MA+ and BA+ exhibit adsorption energies of −5.519 and −5.925 eV, respectively, at MA vacancies on the perovskite surface. This finding indicates that BAI passivation induces surface-healing effects, increasing surface and device stability. The I- components of BAI also replace imperfections at the perovskite interface, affording considerably reduced deep-level anomalies and mitigating nonradiative recombination. This theoretical perspective is supported experimentally via X-ray photoelectron spectroscopy and glow discharge optical emission spectroscopy. BAI passivation and 2D-BA<inf>2</inf>PbI<inf>4</inf> capping lowers work functions for 3D perovskite surfaces, registering at approximately 0.158 and 0.173 eV, respectively, which are lower than those of the control 3D film. Within the 2D/3D perovskite configuration, 2D-BA<inf>2</inf>PbI<inf>4</inf> capping considerably increases the open-circuit voltage in solar cells. In comparison, devices with BAI-enhanced interfaces show improved durability with promise for solar cell applications.
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Impact of a Spun-Cast MoOxLayer on the Enhanced Moisture Stability and Performance-Limiting Behaviors of Perovskite Solar Cells
(2021-04-26)
Rosungnern, Unyamanee
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Kumnorkaew, Pisist
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Kayunkid, Navaphun
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Chanlek, Narong
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Li, Youyong
Organic-inorganic perovskite solar cells (PSCs), which have good environmental durability, are of great interest for practical applications. In this work, we show that a solution-processed MoOx layer acts as a buffer layer against high moisture stress to suppress defects in the perovskite and as a hole transport layer. The inversion of the photoinduced charge migration behaviors, that is, the electron preferentially moving toward the surface when MoOx is directly deposited onto the perovskite, is found to cause a significant loss in device functionality. The deposition of MoOx onto spiro-OMeTAD results in a lower photocurrent density-voltage (J-V) hysteresis behavior, a greatly enhanced electrical conductivity, and a significantly stabilized power conversion efficiency (PCE) when compared with those of devices without the MoOx layer. More importantly, the PCEs of the MoOx-based devices are retained at over 85% of their initial value, while only 75% is retained for a reference cell. This work highlights the facial fabrication approach of the solution-based MoOx layer and provides experimental evidence of the photogenerated charge migration behaviors on the perovskite/MoOx interface. This information would be beneficial for the further design and development of PSC technology.
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Controlling the growth of silver nanoparticles on thin films of an n-type molecular semiconductor
(2015-06-11)
Girleanu, Maria
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Casula, Giulia
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Blanck, Christian
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Schmutz, Marc
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Contal, Christophe
Nucleation and growth of silver nanoparticles were studied on the surface of an n-type organic semiconductor (N,N′-bis(n-octyl)dicyanoperylene-3,4:9,10-bis(dicarboximide) (N1400)) as a function of the deposition rate τ and the substrate temperature T<inf>s</inf>. Electron tomography was used to probe the bulk diffusion of Ag in the N1400 layers. No Ag nanoparticles (NPs) are formed in the bulk of N1400 even for high substrate temperatures, T<inf>s</inf> = 125 °C, indicating that Ag diffusion in the organic semiconductor is marginal. The NP distribution on the surface of N1400 is essentially determined by the surface roughness of the N1400 films. A transition in the nucleation mode of Ag NPs on N1400 is evidenced as a function of T<inf>s</inf>: for T<inf>s</inf> ≥ 50 °C, Ag NPs form random patterns, whereas, for T<inf>s</inf> ≥ 75 °C, linear arrays of aligned NPs are observed. Such arrays result from step edge decoration of the N1400 terraces. The surface density of Ag NPs is thermally activated, but the activation energy depends on the structure of the N1400 films: the smaller the crystal size of the N1400 grains, the larger the activation energy.
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Tailoring ZnO Nanostructures through Precursor Concentration and Hydrothermal Duration: A Pathway to Efficient Solar Water Splitting
(2026-11-10)
Borklom, Phanlapa
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Khemasiri, Narathon
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Jessadaluk, Sukittaya
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Rattanawarinchai, Prapakorn
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Kayunkid, Navaphun
This work investigated the formation of ZnO nanostructures on ITO substrates prepared by self-seeding hydrothermal synthesis for photoelectrochemical ( PEC) water splitting applications. The hydrothermal parameters, precursor concentration and hydrothermal time, were varied to explore their influences on ZnO crystallinity, morphology, and PEC performance. The combinations of X-ray diffraction and field emission scanning electron microscopy revealed highly oriented ZnO nanostructures with diverse morphologies, including small granules, nanorods, dense films, and hexagonal platelets. Topographic profiling of the morphological parameters revealed complex relationships between synthesis conditions and nanostructure characteristics, highlighting the importance of considering aggregation phenomena in substrate-based growth. This aggregation led to deviations from conventional crystal growth theory predictions, particularly for grain density and diameter evolution. PEC performance evaluation identified ZnO nanorods as the optimal morphology, exhibiting a photocurrent density of 0.182 mA/cm² at 0 V vs. Ag/AgCl. Further enhancement was achieved by decorating ZnO nanorods with CdS nanoparticles, resulting in a six-fold increase in photocurrent density (1.2 mA/cm²). This improvement is attributed to expanded light absorption and improved charge separation at the CdS/ ZnO interface. Our findings demonstrate the potential of rationally designed ZnO-based nanostructures in the advancement of solar-driven water splitting technologies and provide valuable insights for optimizing PEC systems through precise control of hydrothermal synthesis parameters, consideration of substrate-induced aggregation, and strategies for photoelectrochemical (PEC) water splitting applications.
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Growth window and metal-insulator transition behavior of VO2 thin films deposited by pulsed laser deposition for thermal switch applications
(2026-05-01)
Jessadaluk, Sukittaya
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Rahong, Sakon
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Kayunkid, Navaphun
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Khemasiri, Narathon
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Rangkasikorn, Adirek
Vanadium dioxide (VO<inf>2</inf>) is a strongly correlated transition metal oxide that exhibits a sharp and reversible metal-insulator transition (MIT) near room temperature, making it a promising material for thermal switching and adaptive electronic applications. In this study, VO<inf>2</inf> thin films were deposited on single-crystalline Si, thermally grown SiO<inf>2</inf>, and fused quartz substrates by pulsed laser deposition, and the influence of substrate temperature and oxygen partial pressure on phase formation, structural properties, and MIT behavior was systematically investigated. By optimizing deposition conditions within a narrow oxygen pressure window, phase-pure monoclinic VO<inf>2</inf>(M) thin films with high crystalline quality were achieved while suppressing the formation of over-oxidized vanadium oxide phases. Structural and chemical analyses using X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed the stabilization of the V4+ oxidation state and uniform film stoichiometry. Temperature-dependent electrical measurements revealed a pronounced and reproducible MIT characterized by an abrupt change in resistance and a clear thermal hysteresis. In-situ temperature-dependent X-ray diffraction further demonstrated a direct correlation between the monoclinic-rutile structural transformation and the electronic transition. Importantly, the MIT behavior was consistently observed across all investigated substrates, indicating robust film growth and substrate tolerance. These results provide insight into the structure-property relationships governing VO<inf>2</inf> thin films and highlight their potential for integration into thermal switch and thermally adaptive device architectures.
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Development of solution-based electrodes from nanocomposite material between PEDOT:PSS and ITO nanoparticles
(2017-01-01)
Watthanarungsarit, Kraisak
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Wirunchit, Supamas
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Rangkasikorn, Adirek
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Kayunkid, Navaphun
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Nukeaw, Jiti
Electrodes based on low-temperature preparation such as ink jet printing have been famously used in plastic electronic devices. The aim of this work is to investigate the specific properties of composite materials between nanoparticles of indium tin oxide (np-ITO) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as an alternative electrode for plastic electronic devices. The composite materials were prepared as a function of np-ITO concentration varied from 1 to 20 w/v%. The 1x1 cm2 hybrid electrodes were fabricated by drop casting method on the microscope slide. This method offers many advantages, including simple preparation, low manufacturing cost and short fabricating time. The electrical resistance of the hybrid films was measured using two-probe measurement. Moreover, the surface morphology of the composited film was explored by optical microscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results clearly suggest that mixing np-ITO with PEDOT:PSS can significantly improve conductivity of the composited system. Average value of electrical resistance measured from np-ITO, PEDOT:PSS and composite film are 87.58 kΩ, 40.33 kΩ and 393 Ω, respectively. The significant reduction of film resistance can be explained by the conducting paths made up by PEDOT:PSS to connect np-ITO domain.
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Blue emission mechanism of NPB/ZnSe hybrid structure
(2007-08-28)
Kayunkid, Navaphun
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Keawprajak, Anusit
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Jaruwanawat, Anuchit
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Nukeaw, Jiti
The electrical and optical properties of organic-inorganic hybrid light emitting diodes (HLED) have been investigated. The HLED is consisted of organic material N,N'-di(naphthalene-1-yl)-N,N'- diphenyl-benzidine (NPB) as a hole transport layer and inorganic material zinc selenide (ZnSe) as an electron transport layer and emitting layer as well. The electrical and optical properties have been characterized by current-voltage measurement and electroluminescence (EL) spectroscopy, respectively. The current of HLED decreases with increasing ZnSc thickness, while the threshold voltage increases. The EL spectrum exhibits two peaks at 457 nm and 500 nm, due to electron-hole recombination from energy gap of ZnSe and recombination from defect states in ZnSe layer, respectively. The emission mechanism is described by electric field in organic and inorganic layers. © 2007 IEEE.
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Structural Models of Poly(cyclopentadithiophene- alt -benzothiadiazole) with Branched Side Chains: Impact of a Single Fluorine Atom on the Crystal Structure and Polymorphism of a Conjugated Polymer
(2015-06-23)
Fischer, Florian S.U.
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Kayunkid, Navaphun
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Trefz, Daniel
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Ludwigs, Sabine
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Brinkmann, Martin
This study describes the impact of a single fluorine atom substitution in the conjugated backbone of poly(cyclopentadithiophene-alt-benzothiadiazole) on the structure and the polymorphism of the polymer bearing 2-ethylhexyl side chains. Controlled growth of the nonfluorinated and fluorinated polymers by solvent vapor annealing (SVA), melt-crystallization on oriented poly(tetrafluoroethylene), and higherature rubbing yield highly crystalline and/or oriented films of a thermodynamically stable polymorph called form I. The single-crystal hk0 and the oriented fiber patterns are obtained in films prepared by SVA and aligned films, respectively. Form I involves a high-symmetry packing of four chains in an orthorhombic cell (Pccn space group) with pseudohexagonal symmetry. The chains are paired into dimers with a 3.6-3.8 Å interchain π-stacking distance and a segregated mode of stacking of cyclopentadithiophene and benzothiadiazole (BT). A single H/F substitution on the BT unit modifies the orientation of the dimers in the unit cell of form I. Absorption and structural properties of this new polymorph are discussed with respect to the classical π-stacking structure obtained from solvent-additive processed films. Evidence of yet another polymorph (form II) highlights the polymorphism of these alternated donor-acceptor copolymers.

Kayunkid, Navaphun

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