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NiO Nanoparticle-Modified PTAA Hole Transport Layers for High-Efficiency and Stable Large-Area Perovskite Solar Cells
(2026-06-22)
Sukgorn, Nuttaya
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Kaewprajak, Anusit
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Lapawae, Komsun
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Sinthiptharakoon, Kitiphat
;
Treetong, Alongkot
The hole transport layer (HTL) plays a central role in governing charge extraction, efficiency, and long-term stability in perovskite solar cells (PSCs). Although poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is widely used as an organic HTL, its limited hole mobility and thermal robustness restrict device durability and scalability. Here, we report a hybrid organic−inorganic HTL formed by incorporating NiO nanoparticles into PTAA to simultaneously improve charge transport and thermal stability. Comprehensive spectroscopic and electrical analyses reveal that NiO incorporation deepens the valence band position, enhances hole mobility, accelerates interfacial hole extraction, and suppresses carrier recombination in PTAA:NiO films. As a result, planar n−i−p PSCs employing PTAA:NiO (10 mg mL−1) achieve a champion power conversion efficiency (PCE) of 20.76%, outperforming pristine PTAA-based devices (19.50%) while retaining 86.5% of their initial efficiency after 6000 h under ISOS-D-1 storage conditions. Importantly, NiO incorporation also improves module-level robustness by mitigating thermally induced interfacial degradation during high-temperature encapsulation. Scalable 10 × 10 cm2 minimodules deliver a PCE of up to 14.18% and retain 85.1% of their initial performance after 5000 h. Furthermore, integrated minimodules successfully powered a standalone PM2.5 monitoring system under indoor illumination, highlighting the practical potential of hybrid-HTL PSCs for durable large-area photovoltaic and low-power Internet-of-Things applications.
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Rational concept for fully designing metal-oxynitride films through reactive gas-timing magnetron sputtering: A case study on zinc oxynitride film
(2025-08-10)
Khemasiri, Narathon
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Chananonnawathorn, Chanunthorn
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Horprathum, Mati
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Pornthreeraphat, Supanit
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Saekow, Bunpot
Amorphous metal-oxynitride films—particularly zinc oxynitride (ZnON)—are emerging as promising materials for next-generation high-speed switching electronics, due to the absence of a potential barrier above the conduction band, unlike metal-doped ZnO. However, conventional reactive magnetron sputtering often face challenges in precisely controlling in an anion ratio, N/(N + O), because of the different reactivities of nitrogen and oxygen gases. In this work, we present a strategy to precisely control both the crystal structure and N/(N + O) ratio in ZnON films using a reactive gas-timing technique. By adjusting the oxygen gas-timing sequence (t<inf>O₂</inf>), we selectively induce different crystalline phases, which are closely related to the nitridation and oxidation of the sputtered Zn atom/cluster. This technique facilitates effective N incorporation into ZnO, enabling a broad range of N/(N + O) ratios from 0.048 to 0.964 and optical band gap variations from 1.49 eV to 3.22 eV. At an optimal t<inf>O₂</inf>, an amorphous phase is formed, attributed to a balanced nitridation and oxidation rate of the sputtered Zn atom/cluster that suppresses crystallization. The resultant amorphous ZnON film exhibits a high carrier mobility of 84.81 cm²/Vs, which is 1.16-fold and 35.89-fold greater than those of the cubic and hexagonal ZnON films, respectively. Our findings highlight the effectiveness of the reactive gas-timing technique as a powerful tool for the rational design of metal-oxynitride films, paving the way for their application in advanced electronic devices.
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Physical feature exploration of nanocrystalline FeSi2 surface with argon plasma etching under varying power
(2023-12-01)
Borwornpornmetee, Nattakorn
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Sittimart, Phongsaphak
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Phatthanakun, Rungrueang
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Nakajima, Hideki
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Paosawatyanyong, Boonchoat
Nanocrystalline (NC) FeSi<inf>2</inf> films were created on Si(111) wafers via direct-current sputtering with facing targets at an ambient temperature, then the films were etched by Ar plasma generated through microwave source at different powers of 50, 100, and 150 W. The surface morphology of the as-coated NC FeSi<inf>2</inf> films showed numerous small uniform crystallites and root-mean-square roughness of 4.65 Å. The surface for each etched NC FeSi<inf>2</inf> film showed appearance of holes and slight increase in the roughness as the power increased. X-ray photoelectron spectra showed that the etching decreased the content of hydrophobic carbon and increased the presence of polar oxide group on the NC FeSi<inf>2</inf> films as the power increased. These changes should be the factor behind the shift from hydrophobic state to hydrophilic state. The contact angle of the unetched NC FeSi<inf>2</inf> film surface was 100.55°, which is hydrophobic. The NC FeSi<inf>2</inf> film's surface reached a minimum contact angle of 35.65°, which belong to hydrophilic state, when the etching power was increased to 150 W. The mechanical properties of NC FeSi<inf>2</inf> films rarely affect by Ar plasma. The change in surface state to nearly superhydrophilic after plasma etching indicate possibility to develop NC FeSi<inf>2</inf> into a self-cleaning surface coating material.
1
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Tailoring the structural and optical properties of fabricated TiO2 thin films by O2 duty cycle in reactive gas-timing magnetron sputtering
(2023-08-01)
Chittinan, Donyawan
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Buranasiri, Prathan
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Lertvanithphol, Tossaporn
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Eiamchai, Pitak
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Tantiwanichapan, Khwanchai
Titanium dioxide (TiO<inf>2</inf>) thin films were deposited on silicon (100) and glass substrates via conventional reactive sputtering and reactive gas-timing (RGT) sputtering techniques. The duty cycle of supplied O<inf>2</inf> gas determined its effect on the properties of the TiO<inf>2</inf> films through spectroscopic ellipsometry (SE). With the best triple-layer model for SE fitting, the films' structure and optical properties were analyzed and compared. The high-resolution transmission electron microscope (HR-TEM) showed good agreement with the structure of the SE model, while the grazing-incidence X-ray diffraction (GIXRD) confirmed the crystallinity of the films. The results showed that the duty cycle was a crucial factor in the deposition rate and crystalline phase of the TiO<inf>2</inf> films. The optical reflectance (%R) spectra were measured by a UV-VIS-NIR spectrophotometer, representing anti-reflection properties at a specific wavelength related to the duty cycle. Moreover, the omnidirectional optical transmittance (Omni-T) profiles were also determined. The results showed that the transmittances (%T) of TiO<inf>2</inf> film near those specific wavelengths were enhanced over the bare glass substrate at a wide angle. In addition, photoelectron spectroscopy (PES) was used to confirm the chemical states and atomic compositions.
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Fabrication and Characterization of Ag–Ta Thin Films by Co-Magnetron Sputtering as Alternative Layer for High Reflection of NIR Radiation
(2023-01-01)
Phae-Ngam, Wuttichai
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Rattana, Tanattha
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Kamoldilok, Surachart
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Kohmun, Kanokporn
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Nakajima, Hideki
Silver–tantalum (Ag–Ta) thin films were fabricated by magnetron co-sputtering on silicon (Si) wafer (100) and glass slide substrates at room temperature. The Ag–Ta thin films were prepared at various deposition times of 5, 10, 20 and 30 s and the physical, structural and optical properties of the Ag–Ta thin films were investigated. It was determined that the thicknesses of the films were 7, 9, 17 and 33 nm, respectively. The results revealed that an increase in the film thickness leads to a monotonic increase in FCC and BCC phase of Ag and Ta, respectively. The work function and stoichiometric of the Ag–Ta thin films were investigated by ultraviolet and X-ray photoemission spectroscopies (UPS and XPS), respectively. The potential of Ag–Ta thin films to be used as low-emission coating was investigated using a spectrophotometer. A UV–VIS–NIR spectrophotometer was used to measure the spectral reflectance in the wavelength range from 300 to 2000 nm. The results showed that the Ag–Ta thin film deposited for 30 s exhibited higher reflectance in NIR region than those of 5, 10, 20 and 30 s. It demonstrated an average reflectance of about 80% and slightly decreased to 75% after being kept in the air atmosphere for 28 days. It can be likewise proposed as an alternative thin film with high reflectance of NIR radiation single layer to develop industrial low-emission coating for cost-effective, clean, and easy adaptation to a large area coating.
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Phase evolution in annealed Ni-doped WO3 nanorod films prepared via a glancing angle deposition technique for enhanced photoelectrochemical performance
(2022-05-15)
Wattanawikkam, Chakkaphan
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Bootchanont, Atipong
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Porjai, Porramain
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Jetjamnong, Chanthawut
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Kowong, Rattanachai
Ni-doped WO<inf>3</inf> nanorod films were fabricated via a reactive magnetron cosputtering with a glancing angle deposition technique. The crystal structure and surface morphology were observed using grazing incident X-ray diffraction and field emission Scanning Electron Microscopy, respectively. The chemical compositions and oxidation state of each element were investigated by X-ray photoemission spectroscopy. The local structure and phase evolution were investigated via X-ray absorption spectroscopy. The local structure of Ni atoms in WO<inf>3</inf> nanorod films is characterized as a NiWO<inf>4</inf> nanocluster in the WO<inf>3</inf> matrix, which is supported by calculated spectra. The phase information obtained after annealing demonstrates that short-length order in amorphous transitions to crystallinity. The phase information of the local structures were acquired and discussed as well as the effect on the annealing process. The coupling of amorphous WO<inf>3</inf>, crystalline WO<inf>3</inf>, and amorphous NiWO<inf>4</inf> exhibits high photoelectrochemical activity of the sample annealed at 400 °C, which was observed with a large current density (2.35 μA/cm2) at 1.20 V vs. Ag/AgCl under visible light irradiation, which is greater than that of the unmodified WO<inf>3</inf> photoelectrode (1.38 μA/cm2).
1
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Synchrotron-based NEXAFS analysis of thermal-treated diamond-like carbon films
(2020-10-01)
Chunjaemsri, Thanun
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Chanlek, Narong
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Sukkha, Usa
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Nakajima, Hideki
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Rujirawat, Saroj
Diamond-like carbon (DLC) film properties are known to vary with important factors such as the ratio of sp3 to sp2 hybridization, film thickness, and contaminations. In this work, the carbon bonding contents in DLC thin films, thermal-treated with various temperatures between room temperature to 250 °C, were studies by near-edge X-ray absorption fine structure (NEXAFS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. From NEXAFS measurements, the sp3/sp2 ratios of DLC films were found to be unaffected by the thermal treatments. The results indicate that thermal treatment below 250 °C does not affect the carbon bonding contents in DLC thin film.
2
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XPS Study of the In/CdTe Interface Modified by Nanosecond Laser Irradiation
(2019-01-01)
Zelenska, Kateryna
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Gnatyuk, Volodymyr
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Nakajima, Hideki
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Mekprasart, Wanichaya
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Pecharapa, Wisanu
The X-ray photoelectron spectroscopy (XPS) with 650 eV synchro-tron radiation was employed to study the In/CdTe diode detector structures formed by laser-induced doping and subjected to multiple Ar-ion etching from the In-coated side. The dependences of the peak areas in the high-resolution Cd 3d and In 3d XPS spectra on the etching number demonstrated the presence of Cd atoms in the In film and In dopant atoms in the CdTe near the In/CdTe inter-face. This was attributed to ultrafast mutual diffusion under laser action. The XPS results were direct evidence of incorporation of In dopant atoms into the surface region of the CdTe crystal and penetration of Cd atoms into the In film.
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Laser Doped Layer in CdTe Diode Detectors Revealed by Synchrotron XPS
(2018-11-01)
Zelenska, Kateryna
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Gnatyuk, Volodymyr
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Nakajima, Hideki
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Pecharapa, Wisanu
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Aoki, Toru
The X-ray photoelectron spectroscopy (XPS) with 650 eV synchrotron radiation was applied to study the modified surface layers in the CdTe diode-type X/γ-ray detectors fabricated by the laser-induced doping techniques. Semi-insulating (111)-oriented p-like CdTe single crystals, pre-coated with an In dopant film, were irradiated by nanosecond pulses of a YAG:Nd laser (λ = 1064 nm). The activation of the In/CdTe interface and doping were carried out by laser irradiation of the metalized samples from the In side or through the semiconductor which was transparent for such wavelength. In the first case, laser-induced doping was attributed to the generation of laser-stimulated stress and shock waves which incorporated In atoms into the CdTe surface region. In the second case, it was possible to directly affect the In/CdTe interface because laser radiation was strongly absorbed by a thin layer of the deposited In dopant film and the CdTe was dissolved in molten In. The distribution of In and Cd atoms with the depth and atomic bonding in the In/CdTe interface were analyzed based on the high resolution In 3d and Cd 3d peaks in the XPS spectra of the formed In/CdTe diode structures subjected to Ar-ion sputtering. The stoichiometry and transformation of electronic structure in the modified CdTe layer were analyzed. Rectification properties of the created In/CdTe/Au diodes were due to the formation of an In enriched submicron layer as result of laser-induced solid-phase or liquid-phase doping that depended on irradiation of the In/CdTe structure from the metalized or semiconductor side, respectively. The created In/CdTe/Au diodes have been promising for X/γ-ray detector application.
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Synchrotron radiation x-ray photoelectron spectroscopic study of CdTe-in structures formed by laser-induced doping technique
(2018-09-05)
Zelenska, Kateryna
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Gnatyuk, Volodymyr
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Mekprasart, Wanichaya
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Pecharapa, Wisanu
;
Nakajima, Hideki
Laser-based doping technique was used in the fabrication of M-p-n structured In/CdTe/Au diodes which are sensitive to X- and γ-rays. CdTe is transparent for infrared radiation that allows irradiating the CdTe-In structures in two different ways: from metal side or through the semiconductor. The obtained In/CdTe/Au diodes were tested by electrical measurements and demonstrated low leakage current and high forward current. The distribution of In and Cd atoms with the depth in the irradiated In-CdTe structures was studied by X-ray photoelectron spectroscopy (XPS) using synchrotron radiation as the excitation light. The excitation energy was 650 eV. The In film, deposited on the CdTe crystal, was sputtered by 3 keV Ar ions during 2 hours between spectra measurements. Total time of sputtering was 10 hours. The XPS spectra for non-irradiated sample, irradiated from the In film side and through the CdTe crystal by 10 infrared laser pulses with power density of 2.5 MW/cm2 were studied. Photoelectron peaks of Cd 3d and In 3d were analyzed. The evidences of laser-induced evaporation of the In film, stress-wave-induced mass transfer, freezing of non-equilibrium defects and subsequent dissolution of CdTe in the laser-molten thin layer of In film are discussed.

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