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Repeated disordered structure for radiative cooling application via scalable stamping method from designed CaCO3 templates
(2026-07-01)
Kaewmanee, Taweesak
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Sakata, Patawee
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Gridtayawong, Pharit
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Rueangsawang, Worawut
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Ponghiransmith, Chattrarat
Radiative cooling via micro-patterned surfaces provides energy-efficient solution for thermal regulation by enhancing selective thermal emission within the atmospheric transparency window (8–13 μm). This study investigates the effects of microstructural patterning through a low-cost and scalable stamping technique. The patterning templates were uniquely produced by the removal of randomly-distributed CaCO<inf>3</inf> polymorphs—calcite and vaterite with specific sizes. The novel calcite-imprinted structures exhibit superior mid-infrared emissivity (>0.96) and maintain consistent temperature reduction across varying weather conditions, outperforming vaterite-based films. However, the cooling performance of unmodified patterns is limited by solar absorption. To address this, TiO<inf>2</inf> (rutile phase) is incorporated into a polymer matrix before being stamped to enhance solar reflectivity. Moreover, hydrophobic aerogels could be inserted between micropattern gaps to facilitate self-cleaning functionality. A composite film containing 3 wt% TiO<inf>2</inf> with the calcite micro-patterning and hydrophobic aerogel achieves a temperature drop of 4.8 °C, compared to 1.2 °C of pristine patterns relative to that of a clear film. For real-world applicability, the optimized patterning strategies were further validated on fiber cement rooftile surfaces, yielding best temperature reductions of 2.5 °C compared to pattern-free coating under a tropical climate. The calculated net cooling power of 3 wt% TiO<inf>2</inf> patterned film with aerogel is 26.9 W/m2. This novel passive-cooling stamping strategy is low-cost, scalable, and suitable for large-area deployment, reducing the energy burden of active cooling technologies.
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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
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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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Titanate Nanosheets/Cellulose Composite Showing Improved Crystallinity and Decreased Water Wettability by Gamma-Irradiation
(2025-11-25)
Tariwong, Yaowaluk
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Pulphol, Phieraya
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Sangtawesin, Tanagorn
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Seriwattanachai, Chaowaphat
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Kanjanaboos, Pongsakorn
While molecularly thin nanosheets have been increasingly studied as functional coatings, their use as a hydrophobic and γ-irradiation-tolerant component in biologically derived matrices is to be demonstrated. Herein, simple dip-coating was employed to fabricate titanate nanosheets/cellulose composites, which were subjected to γ-irradiation up to 50 kGy. Their surface chemistry was evaluated by water contact angle (WCA) measurements and X-ray photoelectron spectroscopy (XPS). Upon irradiation, the WCA of all samples nonmonotonically increased in three stages from ∼29 to 50° (noncoated) and ∼46 to 80° (composite, optimized at ∼1.2 wt %Ti loading, or 0.2 mg·cm–2). The titanium content and the 4+ valence did not change with the dose, suggesting the radiolytic stability. The dual surface modification occurs while cellulose fiber morphology and nanoscale mechanical properties are preserved. The increased WCA at the cellulose-part is explained by the γ-irradiation-induced crystallization according to the increased crystallinity index and improved thermal stability. At the other component, nanosheet coating results in increased surface roughness and diminished water–surface interactions. The latter is deduced from DSC measurements of water evaporation from pristine and 50 kGy-irradiated Cs<inf>0.7</inf>Ti<inf>1.825</inf>O<inf>4</inf>layered crystal-a nanosheet precursor. Our work suggests further exploration of nanosheets with diverse structures and compositions as coatings or fillers, which could find applications in γ-irradiation-sterilized barrier films.
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Highly Flexible Tribovoltaic Nanogenerator Based-on P-N Junction Interface: Comparative Study on Output Dependency Dominated by Photovoltaic Effect in Freestanding-Mode
(2023-10-18)
Sriphan, Saichon
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Worathat, Supakarn
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Pharino, Utchawadee
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Chanlek, Narong
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Pakawanit, Phakkhananan
The emergence of tribovoltaic nanogenerators (TVNGs) paves the way for developing a new kind of semiconductor-based energy harvester that overcomes the restriction of low output current in a conventional approach. The traditional TVNG generally depends on the frictional pair between two rigid semiconductors (or metal-semiconductor), limiting the practicability of flexible and portable electronics. Recent developments require the fundamental understanding of charge generation in diverse operating modes and structures. Here, a flexible TVNG based on the p-Cu<inf>2</inf>O/n-g-C<inf>3</inf>N<inf>4</inf> interface is presented. Operating in a freestanding mode, the proposed TVNG can generate a stable signal in any optical conditions including UV illumination, dark, and ambient. Under UV illumination, the electrical outputs of the TVNG reach 0.43 V and 2.1 µA cm−2, which are significantly larger than those obtained from dark and ambient conditions. The results demonstrate the coupling effect of three phenomena: tribovoltaic, photovoltaic, and triboelectric effects, and the unique mechanism to the observed signal is proposed. Additionally, the TVNG shows the practical feasibility of energy harvesting with capacitor charging and charge-boosting circuits. This study showcases the unique concept with potential for developing a novel flexible nanogenerator in many aspects, including material, structure, and fundamental mechanism.
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Structural, optical, and electrical properties of cellulose/titanate nanosheets composite with enhanced protection against gamma irradiation
(2023-10-01)
Maluangnont, Tosapol
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Kwamman, Tanagorn
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Pulphol, Phieraya
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Pongampai, Satana
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Charoonsuk, Thitirat
Two-dimensional (2D) materials have emerged as a promising functional filler in nanocomposites due to their unique anisotropy and resilience to harsh conditions. We report herein the use of Ti<inf>0.91</inf>O<inf>2</inf> nanosheets as a protective component against γ-irradiation to cellulose paper. The titanate nanosheets were prepared via a sequence of solid-state synthesis of lepidocrocite-type Cs<inf>0.7</inf>Ti<inf>1.825</inf>O<inf>4</inf>, proton exchange to H<inf>0.7</inf>Ti<inf>1.825</inf>O<inf>4</inf>·H<inf>2</inf>O, and exfoliation with tetrabutylammonium hydroxide. The nanosheets were incorporated into the commercial cellulose filter paper by a simple dip coating up to 0.6 mg cm−2, equivalent to 10 wt% TiO<inf>2</inf>. The nanosheets distribution was demonstrated by energy dispersive X-ray (EDX) mapping, synchrotron radiation X-ray tomographic microscopy (SRXTM), and atomic force microscopy (AFM). It is found that γ-irradiation (up to 50 kGy) destroyed the cellulose Iβ crystallinity of uncoated paper, but this is less pronounced in the cellulose/titanate nanosheets composite. This was also confirmed by the lack of a 235 nm-absorption characteristics of irradiation-induced decomposition product(s) in nanosheets-containing papers, which also exhibit UVA shielding property. The coated samples remained white while the uncoated ones were darkened with γ-irradiation. In addition, the nanosheets-coated papers showed dielectric permittivity, loss tangent, and AC conductivity which were invariant of the γ-dose, unlike those from the uncoated ones. Our work demonstrates the use of lead-free Ti<inf>0.91</inf>O<inf>2</inf> nanosheets as a γ-shielding component to slow down/prevent structural, optical, and electrical properties damages in cellulose paper, which could extend to other nature-derived materials.
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Intermediate matching layer for light-induced performance and removable clip-on applications of four-terminal perovskite/silicon heterojunction tandem solar cells
(2023-05-01)
Sanglee, Kanyanee
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Sakunkaewkasem, Siwakorn
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Piromjit, Channarong
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Nukunudompanich, Methawee
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Kanjanaboos, Pongsakorn
Perovskite/silicon tandem solar cells are one of the most efficient ways to improve the performance of the photovoltaic industry and should be viewed as a promising path in the photovoltaic field. The silicon photovoltaic modules have a lifespan of over 20 years, while the low device stability of perovskite solar cells (PSCs) remains a significant commercialization barrier. An air gap acts as an optical spacer layer for four terminal (4T) perovskite/silicon tandem cells, resulting in a loss of efficiency. Using polydimethylsiloxane (PDMS) as an intermediate matching layer (IML) and a clip-on design made of a PDMS-based material sandwiched between polyvinyl chloride (PVC) layers with the configuration of PVC/IML/PVC, this research not only achieved efficiency improvement of four-contact tandem solar cells but also greatly simplified disassembly of individual cells. The 4T perovskite/silicon heterojunction tandem cells with a clip-on design achieved the highest efficiency of 23.49% for the active area of 1 cm2, while the fully tandem configuration without a clip-on layer only exhibited a PCE of 22.83%. The clip-on technology has the potential to boost the current density of silicon heterojunction solar cells from 15.01 mA/cm2 (for the filtered bottom cell with an air gap) up to 16.51 mA/cm2 (for the filtered bottom cell with a clip-on). Therefore, this state-of-the-art allows for the removal of PSCs with a shorter lifespan while adhering two photovoltaic cells together securely and effectively.

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