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We report the microstructure and thermoelectric properties of composite nanofiber webs, which were fabricated by dual-electrospinning of polyacrylonitrile (PAN) and sodium cobalt oxide (NaCo2O4) precursor solutions with different input compositions and following heat-treatment at 600–900 °C for simultaneous carbonation and calcination. The SEM and EDS mapping images revealed that PAN-derived carbon nanofibers (CNFs) and NaCo2O4-based ceramic nanofibers coexisted in the composite nanofiber webs and that their relative contents could be controlled by the input compositions. The Seebeck coefficient increased from ~26.77 to ~73.28 μV/K and from ~14.83 to ~40.56 μV/K with increasing the relative content of NaCo2O4 nanofibers in the composite nanofiber webs fabricated at 700 and 800 °C, respectively. On the other hand, the electrical conductivity of the composite nanofiber webs increased with the decrement of the relative content of NaCo2O4 nanofibers as well as the increment of the heat-treatment temperature. Owing to the opposite contributions of NaCo2O4 nanofibers and CNFs to the Seebeck coefficient, electrical conductivity and thermal conductivity, a maximum power factor of ~5.79 μW/mK2 and a figure of merit of ~0.01 were attained for CNF/NaCo2O4-based composite nanofiber webs fabricated at 45 wt% input composition of NaCo2O4 and at heat-treatment of 700 °C.

Perhydropolysilazane (PHPS), an inorganic polymer composed of Si-N and Si-H, has attracted much attention as a precursor for gate dielectrics of thin-film transistors (TFTs) due to its facile processing even at a relatively low temperature. However, an in-depth understanding of the tunable dielectric behavior of PHPS-derived dielectrics and their effects on TFT device performance is still lacking. In this study, the PHPS-derived dielectric films formed at different annealing temperatures have been used as the gate dielectric layer for solution-processed indium zinc oxide (IZO) TFTs. Notably, the IZO TFTs fabricated on PHPS annealed at 350 °C exhibit mobility as high as 118 cm

Nurses with rotating shifts, including night shifts, have suffered from low physical activity during the COVID-19 pandemic and lower sleep quality due to the disruption of their circadian rhythm. This study aimed to develop and examine the effectiveness of a mobile wellness program on daily steps, sleep quality, exercise self-efficacy, intrinsic motivation for exercise, self-rated fatigue, and wellness. A cluster randomized controlled trial design was used to examine the effectiveness of the mobile wellness program for nurses with rotating shifts. Sixty nurses from one university hospital participated and were allocated to an intervention group and a control group. The intervention group received a 12-week mobile wellness program to improve their physical activity and sleep quality, and the control group was only given a Fitbit to self-monitor their health behaviors. There were significant differences between the two groups in daily steps (p = 0.000), three components (subjective sleep quality, sleep disturbance, daytime dysfunction) of the PSQI, exercise self-efficacy, intrinsic motivation for exercise, and wellness. In conclusion, this study provides meaningful information that the mobile wellness program using Fitbit, online exercise using Zoom, online health coaching on a Korean mobile platform, and motivational text messages effectively promoted physical activity and sleep quality for nurses with rotating shifts during the COVID-19 pandemic.

Small-bundled single-walled carbon nanotube (SSWCNT) nanocomposite films with two different conjugated polymers were facilely prepared by using a micronizing mill. The influence of the difference i...

In this study, poly(vinylidene fluoride-co-hexafluoropropylene)/carbon composite films with enhanced thermoelectric performance are prepared. A hybrid filler of graphite nanoplatelets (GNPs) and single-walled carbon nanotubes (SWNTs) increase the electrical conductivity as a bridge between neighboring GNPs in the carbon hybrid films. The improved electrical conductivity is due to the purification process performed in an acid solution, which effectively removes the amorphous carbon, additives, and impurities in the carbon fillers. The Seebeck coefficient of the composite films is similarly maintained at approximately 40 μV/K owing to the intrinsic properties of the material. The calculated power factor is considerably increased to approximately 14 μW/mK2 owing to purification of the SWNTs, which is twice the value of the highest value reported value for freestanding-type thermoelectric materials based on polymer/carbon composites.

With increasing attention on flexible or wearable power-conversion devices, intensive research efforts have been devoted to flexible organic thermoelectric (TE) modules to replace the brittle inorg...

Free-standing single-walled carbon nanotube (SWCNT)/cellulose acetate composite films were fabricated by a simple bar-coating method. As a paste solvent, acetone, a low-boiling-point solvent, was u...

Carbon nanotube (CNT)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite fibers with the CNT content ranging from 10 to 50 wt% were prepared by a wet-spinning process using a common solvent/coagulation system for application to organic fiber-based thermoelectric generators. After post-treatments, such as immersion in hydrazine solutions and polyethyleneimine-infiltration, the thermoelectric properties of the CNT/PEDOT:PSS composite fibers were optimized, with p- and n-type power factors of 83.2 ± 6.4 and 113 ± 25 μW m−1 K−2, respectively. The electrical power generation capability of an organic fiber-based thermoelectric generator assembled with the p- and n-type CNT/PEDOT:PSS composite fibers was confirmed.

Small-bundled single-walled carbon nanotube (SSWCNT) nanocomposite films made with various small molecules were facilely fabricated using the micronizing mill process. Finely dispersed small molecules in the SSWCNT film can effectively reduce the in-plane thermal conductivity of the nanocomposite due to π-π interactions. Furthermore, the micronizing mill process ensures the uniform distribution of the small molecules and the SSWCNTs in the nanocomposite film without any damage or deformation of the SSWCNT structure. Moreover, the influence of the shape of the small molecules on the thermoelectric properties of SSWCNT nanocomposite was systematically investigated. The thermoelectric properties of the pyrene/SSWCNT nanocomposite were found to have been greatly improved by the planar pyrene molecules with a slightly increased electrical conductivity of 978.6 S cm−1 and a significantly decreased in-plane thermal conductivity of 13.5 W m-1 K-2. The evaluated ZT value of the pyrene/SSWCNT nanocomposite was 4.4 × 10−3 and is about 20 times higher than that of the pristine SSWCNT nanocomposite. A planar-type thermoelectric generator (TEG) consisting of 20 legs was also fabricated using this pyrene/SSWCNT nanocomposite. The TEG showed an open circuit voltage of 20 mV and a short circuit current of 350 μA, resulting in a maximum output power of 1.5 μW at ΔT = 20 °C.

High-performance thermoelectric composite fibers were prepared via simple wet-spinning of single-walled carbon nanotube (SWCNT)/poly(vinylidene fluoride) (PVDF) pastes using a common solvent/coagulation system. By improving the content and dispersion state of SWCNTs in the composite fibers, the thermoelectric performance could be effectively enhanced. With n-type doping of SWCNTs using polyethylenimine, high-performance n-type SWCNT/PVDF composite fibers could be prepared. The power factors of the p- and n-type SWCNT/PVDF composite fibers with the SWCNT content of 50 wt% were 378 ± 56 and 289 ± 98 μW m-1 K-2, respectively. The electric power generation capability of an organic thermoelectric generator with the p- and n-type composite fibers was confirmed.

In this study, we prepared a thermoelectric device with p-type organic thermoelectric hybrid film and n-type buckypaper. Both the film and buckypaper are made of a hybrid filler of graphite nanoplatelets (GNPs) and single-walled carbon nanotubes (SWNTs). The p-type thermoelectric hybrid film has a free-standing form and enhanced thermoelectric performance owing to a polyvinylidene fluoride/carbon hybrid film purified with an acid solution, which successfully eliminates amorphous carbon, additives, and impurities. The n-type thermoelectric buckypaper was made with a filtration method with GNPs and SWNTs to the membrane filter. To convert this to an n-type thermoelectric property, a polyethyleneimine solution was also added by filtration process. In addition, adding sodium dodecyl benzene sulfonate during carbon dispersion enhanced thermoelectric performance, which was confirmed by measuring the electrical conductivity and Seebeck coefficient. A thermoelectric device using silver electrodes was produced with the thermoelectric composite film and buckypaper to verify its thermoelectric voltage and generating power.

We developed an unconventional route to produce uniform and intimately interfaced nanocomposite films for their potential application in thermoelectric (TE) devices. Here, amino-terminated poly(3-hexylthiophene-2,5-diyl) (P3HT) was chemically adhered onto the surface of a functionalized double-walled carbon nanotube (DWCNT), via an amidation reaction, to form P3HT-grafted DWCNT (P3HT-g-DWCNT). As the P3HT chains are intimately and permanently tethered on the DWCNT surface, a well-defined P3HT/DWCNT interface prevents the DWCNT from aggregating by promoting the solubility of P3HT-g-DWCNT nanocomposites in organic solvent. Such characteristic changes in DWCNT by polymer grafting can improve the thermoelectric properties of DWCNT films. The covalently grafted P3HT-g-DWCNT film exhibits a significantly enhanced Seebeck coefficient of 116. 6 μV K−1, as compared to a physically mixed P3HT/DWCNT composite (69.2 μV K−1), in conjunction with a high power output in TE modules. This facile approach would open a new way to synthesize intimately connected nanocomposites made up of conductive polymers and carbon materials for high performance thermoelectrics.

This study demonstrates a post-treatment method for enhancing the thermoelectric power factor of carbon nanotube (CNT)/conjugated polymer nanocomposite films. For the fabrication of the nanocomposite films a mixture of P3HT (50 wt%) and few-walled CNT (50 wt%) in o-dichlorobenzene (oDCB), or a mixture of PEDOT:PSS (50 wt%) and few-walled CNT (50 wt%) in distilled deionized (DDI) water was used. The uniaxial hot-pressing treatment of the as-prepared nanocomposite films resulted in their densification and increased the electrical conductivity and power factor. It was found that the thermoelectric power factor of the CNT/P3HT and CNT/PEDOT:PSS nanocomposite films increased from 150 ± 9 to 217 ± 30 μW m−1K−2, and from 371 ± 44 to 572 ± 92 μW m−1K−2, respectively, after hot-pressing. We fabricated organic thermoelectric generators using the hot-pressed CNT/conjugated polymer nanocomposites and evaluated their capabilities of electrical power generation. The maximum power outputs of the hot-pressed CNT/P3HT and CNT/PEDOT:PSS OTEGs were 46.0 and 36.3 nW, respectively, under a temperature difference of 10 K.

The electrical conductivity and doping stability of poly(3-hexylthiophene) (P3HT) in ambient air are significantly improved using a gold chloride dopant, where the coexistence of AuCl4− and Au nanoparticles contributes to high electrical conductivity and doping stability at the same time. The uniformly formed Au nanoparticles induce a facile charge transfer in a thin film of AuCl3-doped P3HT as examined by the crystallography and transmission electron microscopy. P3HT doped with AuCl3 exhibits a high electrical conductivity of 207 S cm−1, a Seebeck coefficient of 73.9 μV K−1, and an optimized power factor of 110 μW m−1 K−2. Importantly, AuCl3-doped P3HT shows excellent air stability. After exposure to the ambient condition for 300 h, the optimized power factor of the AuCl3-doped P3HT maintains over 80% of the initial, whereas that of the FeCl3-doped P3HT decreases to only 20% of the original. Finally, a flexible and organic thermoelectric generator (OTEG) is fabricated using the AuCl3-doped P3HT by slot-die coating. The OTEG shows a relatively high open-circuit voltage (Voc) of 7.96 mV and a short-circuit current (Isc) of 0.93 μA, resulting in a power density of 18.5 nW cm−2 at a temperature gradient of 10 °C.

The thermoelectric properties of telluride nanorods coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (Te-PEDOT:PSS) were enhanced by the addition of a small amount of a nanocarbon material such as graphene nanoparticles (GNPs) or small bundled single-walled carbon nanotubes (SSWNTs). In order to apply the nanocarbon composite material to the printing process, soluble Te-PEDOT:PSS was mixed with a small amount of nanocarbon without degrading the thermoelectric performances. The thermoelectric properties of the Te-PEDOT:PSS nanocomposites were greatly improved, especially when a rather small amount of SSWNTs was added to Te-PEDOT:PSS owing to the structural and electrical properties of the SSNWTs. The power factor of Te-PEDOT:PSS films mixed with 0.3 wt% of SSWNTs was optimized to be 206 μW m−1 K−2, with a Seebeck coefficient of 118 μV K−1 and electrical conductivity of 139 S cm−1. The fabricated thermoelectric generator (TEG) with SSWNT-mixed Te-PEDOT:PSS by spray printing showed output power of 126 nW, which is 18 times higher than that of GNP-mixed Te-PEDOT:PSS. Using the SSWNT-mixed Te-PEDOT:PSS solution, a lightweight, flexible, and highly efficient TEG was fabricated by an all-printing process, and it could generate a small amount of electricity with heat from the human body.

The development of n-type polymers and composites to pair with their p-type counterparts in current flexible thermoelectric (TE) generators is crucial to reach the full potential of these devices. However, this development has lagged behind because of difficulties associated with n-type doping of organic semiconductors. Our study focused on the doping characteristics of directly spun carbon nanotube (CNT) webs using various n-type dopants in combination with thermal desorption of oxygen from the CNT web surface for more effective n-type doping. Annealing of the CNT web followed by treatment with 2 mg mL−1 benzyl viologen (BV) resulted in a maximum power factor of 3103 μW m−1 K−2, which was superior to that of a BV-treated pristine CNT web without thermal annealing (1901 μW m−1 K−2). This value is the highest among organic TE materials and similar to that of the most promising inorganic material, Bi2Te3 at room temperature. In addition to the effect of BV dopants on the electrical properties, the thermal diffusion property of the BV-doped CNT web was analyzed using the finite element method. The dopant coating on the CNT bundle efficiently suppressed the phonon transfer along the CNT web direction, which led to a reduction of the thermal conductivity of the CNT web. As a counterpart for the n-type CNT web, p-type TE materials with a thermal power of 2252 μW m−1 K−2 were also prepared using molecular dopants of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane. Finally, a p–n junction-type TE module with an unprecedented power density of 1.18 mW cm−2 was fabricated based on the development of these competitive n-type TE materials.

In this study, a stretchable and elastic thermoelectric (TE) generator with high durability is fabricated and various TE properties are measured and calculated while the compressive pressure is applied to the TE generator. For the elastic TE generator, porous TE sponges are prepared by coating a sponge with single-walled carbon nanotube ink; their TE properties are then systematically measured depending on external strain on the sponge. The TE properties of the porous TE sponge, such as electrical conductivity, power factor, and zT value, increase when compressive strain is increased from 0 to 80% via a controlled change in pore size and density. In addition, p- and n-type TE sponges for the TE sponge generator are prepared easily by simple molecular doping. The maximum output power of the TE sponge generator with 8 p-n pairs is dramatically increased from 0.17 to 2.09 μW at a temperature difference of 55 K under compressive strain of 0 to 80%. These experimental results correspond well with the output power calculated as a function of strain. This elastic and compressive TE material has the potential to be applied in various new TE applications, especially for stretchable and flexible heat sources.

To utilize human heat energy as a permanent power source, we demonstrate, for the first time, an intrinsically highly foldable and stretchable thermoelectric generator that is based upon chemically exfoliated 1T-transition metal dichalcogenide (TMDC) nanosheets (NSs) for self-powered wearable electronics. The power factors of WS2 (n-type) and NbSe2 (p-type) NS films were evaluated to be 5–7 μ K−2 m−1 and 26–34 μW K−2 m−1, respectively, near room temperature. With these films, parallel-connected thermoelectric generators that were fabricated were able to constantly produce up to 38 nW of output power at Δ60 K. The thermoelectric device stably sustained its performance, even after 100 bending cycles and after 100 stretching cycles (50% strain). By direct observation, we found that the film is highly stretched by partial tearing and folding but still maintains an electrical percolation pathway. The morphology then is quickly recovered by a plug-in contact between the torn parts as the external strain is released. Finally, we demonstrate the electric power generation from a prototype wearable thermoelectric generator that was woven into a wristband fitted on a real human body.

Solution-processable telluride-based heterostructures coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (Te-Bi2Te3/PEDOT:PSS) were synthesized through a solution-phase reaction at low temperatures. The water-based synthesis yieldedPSS-coated Te-Bi2Te3 nano-barbell structures with a high Seebeck coefficient that can be stably dispersed in water. These hybrid solutions were deposited onto a substrate by the spray-printing method to prepare thermoelectric generators. The thermoelectric properties of the Te-Bi2Te3/PEDOT:PSS hybrid films were significantly enhanced by a simple acid treatment due to the increased electrical conductivity, and the power factor of those materials can be effectively tuned over a wide range depending on the acid concentration of the treatment. The power factors of the synthesized Te-Bi2Te3/PEDOT:PSS hybrids were optimized to 60.05 μW m(-1) K(-2) with a Seebeck coefficient of 93.63 μV K(-1) and an electrical conductivity of 69.99 S cm(-1). The flexible thermoelectric generator fabricated by spray-printing Te-Bi2Te3/PEDOT:PSS hybrid solutions showed an open-circuit voltage of 1.54 mV with six legs at ΔT = 10 °C. This approach presents the potential for realizing printing-processable hybrid thermoelectric materials for application in flexible thermoelectric generators.

This study investigates a post treatment method for improving the thermoelectric properties of carbon nanotube (CNT)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) nanocomposite films. Ethylene glycol (EG) treatment is performed by immersing the as-prepared CNT/PEDOT:PSS nanocomposite films in EG for 1 h followed by annealing at 140 °C for 10 min. Non-complexed PSS chains could be effectively removed using the EG treatment, resulting in a decrease in inter-bundle distances in the nanocomposite films. This drastically increases the electrical conductivity of the PEDOT:PSS matrix. EG-treated nanocomposite films with 20 wt% CNTs exhibited the highest power factor of 151 ± 34 μW m−1 K−2 among all the prepared samples. Our results indicate that the EG treatment is a promising method for fabricating cost-effective, high-performance thermoelectric CNT/PEDOT:PSS nanocomposite films. We fabricated an organic thermoelectric generator using EG-treated CNT/PEDOT:PSS nanocomposite patterns and evaluated its electric power generation capabilities.

The influence of processing conditions, such as ink concentration and coating method, on the thermoelectric properties of SWCNT/P3HT nanocomposite films was investigated systematically. Using simple wire-bar-coating, SWCNT/P3HT nanocomposite films with high thermoelectric performance could be obtained without additional P3HT doping. The wire-bar-coated SWCNT/P3HT nanocomposite films exhibited power factors of up to 105 μW m(-1) K(-2) at room temperature. The SWCNT bundles with diameters in the range of 6-23 nm formed an interconnected network in the wire-bar-coated nanocomposite films. Network formation in these nanocomposite films was expected to be strongly related to the development of electrical pathways due to inter-SWCNT bundle connections. This study suggests that the thermoelectric performance of SWCNT/P3HT nanocomposite films could be optimized by controlling their processing conditions and morphology.

The influence of film thickness and crystallinity of poly(3-hexylthiophene) (P3HT) on the thermoelectric properties of doped P3HT films was systematically investigated. To obtain excellent thermoelectric properties, highly crystalline P3HT films were prepared by simple wire-bar-coating. The P3HT films doped with a ferric chloride exhibited power factors of up to 35.0 μW m−1 K−2 at room temperature. This study suggests that it could be possible to optimize the thermoelectric properties of the conjugated polymer films by controlling the film thickness and polymer structure. Further, the processing method and conjugated polymers selected for thermoelectric applications should be considered carefully because they determine the final characteristics of the films produced.

This study investigates a coating method for doping a single-walled carbon nanotube (SWCNT)/poly(3-hexylthiophene) (P3HT) hybrid film. In the hybrid film, P3HT chains were very highly doped by simple spin-coating of a FeCl3/nitromethane solution. Hybrid films doped by spin-coating exhibited power factors of 267 ± 38 µW m−1 K−2, which is an improvement over that of hybrid films doped by conventional immersion, 103 ± 24 µW m−1 K−2. The excellent thermoelectric performance is originated from the dramatically increased electrical conductivity by the sufficient doping of P3HT in the hybrid films.

This study demonstrates the fabrication of high-performance thermoelectric carbon nanotube/poly(3-hexylthiophene) (CNT/P3HT) nanocomposite films and flexible CNT/P3HT organic thermoelectric generators (OTEGs) by spray-printing. The spray-printed few-walled CNT/P3HT nanocomposite films exhibited excellent thermoelectric properties. The Seebeck coefficient, electrical conductivity, and power factor of the nanocomposite films were 97 ± 11 μV K−1, 345 ± 88 S cm−1, and 325 ± 101 μW m−1 K−2, respectively, at room temperature. We fabricated flexible OTEGs solely from p-type CNT/P3HT nanocomposite patterns spray-printed on a polyimide substrate, and confirmed their electric power generation capabilities.

We studied the thermoelectric properties of a diketopyrrolopyrrole-based semiconductor (PDPP3T) via a precisely tuned doping process using Iron (III) chloride. In particular, the doping states of PDPP3T film were linearly controlled depending on the dopant concentration. The outstanding Seebeck coefficient of PDPP3T assisted the excellent power factors (PFs) over 200 μW m−1K−2 at the broad range of doping concentration (3–8 mM) and the maximum PF reached up to 276 μW m−1K−2, which is much higher than that of poly(3-hexylthiophene), 56 μW m−1K−2. The high-mobility of PDPP3T was beneficial to enhance the electrical conductivity and the low level of total dopant volume was important to maintain high Seebeck coefficients. In addition, the low bandgap PDPP3T polymer effiectively shifted its absorption into near infra-red area and became more colorless after doping, which is great advantage to realize transparent electronic devices. Our results give importance guidance to develop thermoelectric semiconducting polymers and we suggest that the use of low bandgap and high-mobility polymers, and the accurate control of the doping levels are key factors for obtaining the high thermoelectric PF.

The fabrication of an active-matrix liquid-crystal display by using printing processes offers the potential to reduce the number of photolithography steps and the manufacturing costs. In this study, we prepare the indium-zinc-oxide (IZO) thin-film transistors (TFTs) by using non-vacuum processes such as inkjet printing. The self-assembled monolayers of hexadecanethiol (HDT) on the surface of the oxide semiconductor prior to the inkjet printing of Ag were employed to modify the electric barrier between the IZO and the printed Ag. The field-effect mobility of the IZO TFTs with 0.5-mM HDT treatments and with the inkjet-printed Ag electrodes that were investigated by using their current-voltage characteristics was approximately 0.36 cm2/Vs.

We prepared a poly(imide-benzoxazole) gate insulator for solution-processed flexible metal oxide thin-film transistors (TFTs). The electrical insulating property of the poly(imide-benzoxazole) gate insulator is maintained up to at least 350 °C. The 350 °C-annealed indium-zinc oxide (IZO) TFT with the poly(imide-bezoxazole) gate insulator showed excellent TFT performance with the field-effect mobility of 9.2 cm2 V−1 s−1 and the on/off current ratio of 1.5 × 106. A flexible IZO TFT with the poly(imide-bezoxazole) gate insulator was also fabricated directly on a flexible Kapton substrate. The flexible IZO TFT with the poly(imide-bezoxazole) gate insulator could be operated during bending. Before bending, the mobility and on/off current ratio were 4.1 cm2 V−1 s−1 and 4.7 × 105, respectively. During bending with a radius of 10 mm, the mobility was maintained and the on/off current ratio was slightly decreased to 3.2 × 105.

Indium zinc oxide (IZO) thin films were fabricated via self-combustion of In and Zn salts coordinated with fuel and oxidizer ligands. The intense heat generated from the exothermic reaction compensated for the energy required for oxide formation and reduced the temperature required to anneal the oxide films. Thermal analysis of the fuel and oxidizer precursors confirmed the generation of exothermic heat at a relatively low annealing temperature. With the aid of the internal energy that evolved as heat from the combustion reaction, the formation of the metal–oxygen–metal lattice and the removal of organic ligands could be easily accomplished with lower amounts of externally supplied energy. IZO thin-film transistors (TFTs), obtained from this combustive In–Zn pair at a low annealing temperature of 350 °C, showed a significantly enhanced field-effect mobility of 13.8 cm2 V−1 s−1 and a high on/off current ratio of 1.06 × 108. Inkjet printing of the combustive precursors yielded TFTs with a high field-effect mobility of 5.3 cm2 V−1 s−1 and an on/off ratio of 106. The high performance, good device uniformity, and high yield of TFTs fabricated by our self-combustion method demonstrate the potential of the proposed system to facilitate the processing of flexible printed electronics.

We report the fabrication of high-performance metal oxide thin-film transistors (TFTs) with AlOx gate dielectrics using combustion chemistry in a solution process to provide energy to convert oxide precursors into oxides at low temperatures. Our self-combustion system utilizing two Al precursors as a fuel and an oxidizer is systematically compared with conventional combustive Al precursors with urea in terms of combustion efficiency and dielectric properties. AlOx gate dielectric layers are spin-coated from a solution of combustive AlOx precursors in 2-methoxyethanol and annealed at 250 °C. In this process, organic compounds can be introduced to improve the resulting layer morphology. The thermal behaviors of the self-combustive AlOx precursors are investigated and compared with those of noncombustive AlOx precursors and combustive urea–AlOx precursors to evaluate the generation of exothermic heat at a relatively low annealing temperature. The AlOx dielectrics prepared from self-combustive precursors have uniform and smooth surfaces, low leakage current densities, and high dielectric constants above 8.7. They also exhibit excellent insulating properties and no breakdown at high electric fields. Furthermore, the ZnO TFTs prepared to confirm the operation of the AlOx gate dielectrics show a good mobility of 24.7 cm2 V−1 s−1 and an on/off ratio of 105. It is believed that the AlOx dielectrics prepared using the self-combustion reaction at a low temperature can form a good interface facilitating the growth of desirable ZnO crystal structures, which leads to a considerable improvement in ZnO TFT performance.

We suggest the fabrication of foldable thermoelectric (TE) materials by embedding conducting polymers into Au-doped CNT webs. The CNT bundles, which are interconnected by a direct spinning method to form 3D networks without interfacial contact resistance, provide both high electrical conductivity and high carrier mobility. The ZT value of the spun CNT web is significantly enhanced through two simple processes. Decorating the porous CNT webs with Au nanoparticles increases the electrical conductivity, resulting in an optimal ZT of 0.163, which represents a more than 2-fold improvement compared to the ZT of pristine CNT webs (0.079). After decoration, polyaniline (PANI) is integrated into the Au-doped CNT webs both to improve the Seebeck coefficient by an energy-filtering effect and to decrease the thermal conductivity by the phonon-scattering effect. This leads to a ZT of 0.203, which is one of the highest ZT values reported for organic TE materials. Moreover, Au-doped CNT/PANI web is ultralightweight, free-standing, thermally stable, and mechanically robust, which makes it a viable candidate for a hybrid TE conversion device for wearable electronics. When a 20 K temperature gradient is applied to the TE module consisting of seven p-n couples, 1.74 μW of power is generated.

Highly conductive indium zinc oxide (IZO) thin films were successfully fabricated via a self-combustion reaction for application in solution-processed thermoelectric devices. Self-combustion efficiently facilitates the conversion of soluble precursors into metal oxides by lowering the required annealing temperature of oxide films, which leads to considerable enhancement of the electrical conductivity of IZO thin films. Such enhanced electrical conductivity induced by exothermic heat from a combustion reaction consequently yields high performance IZO thermoelectric films. In addition, the effect of the composition ratio of In to Zn precursors on the electrical and thermoelectric properties of the IZO thin films was investigated. IZO thin films with a composition ratio of In:Zn = 6:2 at the low annealing temperature of 350 °C showed an enhanced electrical conductivity, Seebeck coefficient, and power factor of 327 S cm(-1), 50.6 μV K(-1), and 83.8 μW m(-1) K(-2), respectively. Moreover, the IZO thin film prepared at an even lower temperature of 300 °C retained a large power factor of 78.7 μW m(-1) K(-2) with an electrical conductivity of 168 S cm(-1). Using the combustive IZO precursor, a thermoelectric generator consisting of 15 legs was fabricated by a printing process. The thermoelectric array generated a thermoelectric voltage of 4.95 mV at a low temperature difference (5 °C). We suggest that the highly conductive IZO thin films by self-combustion may be utilized for fabricating n-type flexible printed thermoelectric devices.

*, **Department of Architecture & Ocean Space, Korea Maritime University, Busan 606-791, Korea †Department of Oceanic Architectural Eng., Graduate School, Korea Maritime University, Busan 606-791, Korea요 약 :최근 해상을 비롯한 수상공간에 다양한 플로팅 건축물이 계획되거나 설치되고 있다. 그러나 관련 법제도의 미비로 인하여 플로팅 건축물의 설계 및 건설 혹은 관리운영에서 많은 문제점이 발생되고 있으며 이는 플로팅 건축물의 활성화를 저해하는 중요한 요인이 되고 있다. 따라서 본 연구에서는 플로팅 건축물에 대한 국내 법제도 적용 사례 및 해외 관련 법제도 사례 조사를 실시하여 우리나라에서 플로팅 건축물의 법제도 개선을 위한 기초자료와 개선방향을 제시하였다. 연구결과 플로팅 건축물은 선박이 아닌 건물로서 법적 지위를 확보하며 플로팅 건축물 설치 특별구역을 설정하여 건물의 대지를 조성하고 별도 기술기준을 적용하며 건축인허가 및 등기 절차를 활용할 수 있도록 법제도 개선이 필요하다.핵심용어 : 플로팅 건축물, 건축법, 법제도개선, 사례연구, 국내외사례 Abstract : Recently many different floating buildings are planed and constructed in the sea, river, etc. for active use of water spaces. But many problems are occurred in the process of floating building design, construction and management due to the inadequate legal system. This incomplete legal system has become one of the critical factors which are hampering the invigoration of floating buildings. Therefore this study is to suggest preliminary data and improvement directions through a case study with domestic and foreign examples of appropriate laws and law applications concerning floating buildings. As the results of this study the laws related to floating building have to be revised in the directions of qualifying legally floating building as 'building' but not 'ship', designating 'special zone' for floating building site, and applying the established 'building licensing procedure' to floating building also. Key words :floating building, building law, legal system improvement, case study, domestic and foreign examples * 대표저자: 종신회원, hansk@hhu.ac.kr 051)410-4581 ** 연회원, mklee@hhu.ac.kr 051)410-4584 †교신저자: 연회원, hun0707@hhu.ac.kr 051)410-4995 (주) 이 논문은 2011년 한국항해항만학회 추계학술대회에서 “플로팅 건축물 법제도 사례 연구”로 발표된 것을 발전시켜 정리한 것임.

The systematic criteria and rational standard for site selection of marine recreational floating architecture are in urgently need in respect of structural safety, use of facilities, economics of construction and management, relationship with surrounding areas or cities and impact on marine environment. Nevertheless, at present, there is not any study nor guideline for site selection of marine recreational floating architecture which is now being planned and elected at many places of a body of water such as river or coastal area all over the country. Therefore this study is to propose a systematic process and a rational criteria and guideline for site selection of marine recreational floating architecture. Especially the results are suggested in forms of diagrams and tables in order to be utilized so easily by related local governments and individual enterprises.

This study is on the spatial composition of accommodation area in accommodation barge. The accommodation barge which is used as living facilities for offshore plants` workers can be classified into Accommodation Work Barge, Accommodation Pipe Lay Barge and Multi-purpose Accommodation Barge. We study on the spatial composition of accommodation area in Accommodation Work Barge, most frequently used, through analyzing G.A drawings of the barges. The spatial composition has great influences into the convenience and amenity for workers` daily life in the accommodation area of accommodation barge. The spatial composition of accommodation area shows many characteristics not in horizontal arrangement on any deck but in vertical space arrangement on layers of decks. The particular types of vertical space composition can be classified into `Centralized Type` and `Dispersive Type`. These two types will be the basis of space planning for new accommodation barge.

This study examined the anode material properties of indium tin oxide (ITO) films deposited by pulsed DC magnetron sputtering as well as the device performance in organic light emitting diodes (OLEDs). The surface and electrical properties of the deposited ITO films were examined at various substrate temperatures. Increasing the substrate temperature enhanced the electrical properties of all deposited ITO films. The ITO film deposited at 400 °C showed the best properties, such as a low resistivity of 2.03 × 10−4 Ω cm and high carrier concentration of 7.95 × 1020 cm−3. X-ray photoelectron spectroscopy (XPS) of the deposited ITO films revealed a relatively lower surface work function than the commercial ITO (C-ITO) films. The OLED device with an ITO anode film deposited at 400 °C showed excellent brightness of 26,702.13 cd/m2 at 12.8 V, which was better than that of the OLED with a C-ITO anode.

This study examined the anode material properties of Ga-doped zinc oxide (GZO) thin films deposited by pulsed DC magnetron sputtering along with the device performance of organic light emitting diodes (OLEDs) using GZO as the anode. The structure and electrical properties of the deposited films were examined as a function of the substrate temperature. The electrical properties of the GZO film deposited at 200 °C showed the best properties, such as a low resistivity, high mobility and high work function of 5.3 × 10− 4Ω cm, 9.9 cm2/Vs and 4.37 eV, respectively. The OLED characteristics with the GZO film deposited under the optimum conditions showed good brightness > 10,000 cd/m2. These results suggest that GZO films can be used as the anode in OLEDs, and a lower deposition temperature of 200 °C is suitable for flexible devices.

Transparent conductive 5 at.% Ga -doped ZnO (GZO) thin films are deposited on a glass substrate by an asymmetrical bipolar-pulsed DC magnetron sputtering at various substrate temperatures. All the GZO films have nanocrystalline structure and compact surface morphology. A highly c-axis oriented GZO film was grown perpendicular to the substrate at the 200C. The measured work function of GZO film deposited at 200°C shows slightly lower value of 4.37 eV than a commercial ITO film of 4.6 eV. The GZO film showed the lowest sheet resistance of 35 Ω/□, a carrier concentration of 1.2 ×1021 cm -3, a mobility of 9.9 cm2/Vs, and high optical transmittance of over 85% in the visible range. It indicates that the GZO films at 200°C can be promising as an alternative to ITO thin film for transparent electrode applications.

Antireflection (AR) nanostructures are fabricated on a glass substrate using hybrid nano-patterning lithography (H-NPL) consisting of nanosphere lithography (NSL) and UV-nanoimprint lithography (UV-NIL). The shape and diameter of the AR nanostructures were controlled by fabricating Si masters with different RIE conditions. The shapes of the AR nanostructures were a pillar-type and a corn-type. The diameters of the AR nanostructures were about 350 and 250nm, respectively. AR nanostructures were successfully nanoimprinted on glass in accordance with Si master prepared by NSL. The pillar-type AR nanostructure with diameter of 350nm exhibited the transmittance of over 98% in the wavelength range from 1100 to 2200nm. From the results, the fabricated AR nanostructures demonstrate the possibility to improve the efficiency of optoelectronic devices such as a photo-detector and an IR-LED.

We synthesized vertically aligned ZnO nanowires on SiO 2 wafer using the Au, ZnO and Au/ZnO seed layers through the physical vapor deposition process. The growth direction of ZnO nanowire was controlled by using the three different seed layers. From the XRD results, we observed the highest intensity of the (002) peak on the Au/ZnO seed layer among the three seed layers. The SEM images show that all of the ZnO nanowires have an average diameter of about 100 ~ 200 nm and a length of about 5 μm, and the nanowires grown on the Au/ZnO seed layer are oriented the most perpendicularly to the substrate surface. From the PL analysis, we observed that the intensity of broad emissions at 400–600 nm relating the green emission for the ZnO nanowires on the Au/ZnO seed layer was much weaker than that for the ZnO nanowires on the ZnO seed layer. The experiment results indicate that the selection of seed layers is important to grow nanowires vertically for the application of nanoscale devices.

The thermoelectric properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and tellurium-PEDOT:PSS (Te-PEDOT:PSS) hybrid composites were enhanced via simple chemical treatment. The performance of thermoelectric materials is determined by their electrical conductivity, thermal conductivity and Seebeck coefficient. Significant enhancement of the electrical conductivity of PEDOT:PSS and Te-PEDOT:PSS hybrid composites from 787.99 and 11.01 to 4839.92 and 334.68 S cm−1, respectively was achieved by simple chemical treatment with H2SO4. The power factor of the developed materials could be effectively tuned over a very wide range depending on the concentration of the H2SO4 solution used in the chemical treatment. The power factors of the developed thermoelectric materials were optimized to 51.85 and 284 μW m−1 K−2, respectively, which represent an increase of four orders of magnitude relative to the corresponding parameters of the untreated thermoelectric materials. Using the Te-PEDOT:PSS hybrid composites, a flexible thermoelectric generator that could be embedded in textiles was fabricated by a printing process. This thermoelectric array generates a thermoelectric voltage of 2 mV using human body heat.

We have investigated the microstructure, electrical and magnetic properties of the ZnCoO thin films, which were prepared by the asymmetrical bipolar-pulsed DC magnetron sputtering as a function of substrate temperature. The structural properties of ZnCoO films were characterized with a high resolution XRD. The XRD patterns of the ZnCoO films showed a strong (0 0 2) preferential orientation. The average crystallite size was 23–35 nm, which was estimated from full width at half maximum of XRD results. The electrical resistivity of the films were measured by the van der Pauw method through Hall measurement and showed below 10−1 Ω cm above 300 °C. The magnetic properties of the ZnCoO films were analyzed by the alternating gradient magnetometer at room temperature. All of the films were exhibited the ferromagnetic nature. The high conductivity and room temperature ferromagnetism of the ZnCoO films above 300 °C suggested that the possibility for the application to diluted magnetic semiconductors.