期刊 2017

Chun-Jen Shih, Chih-Chien Lee, Ying-Hao Chen, Sajal Biring, Gautham Kumar, Tzu-Hung Yeh, Somaditya Sen, Shun-Wei Liu, Ken-Tsung Wong

An exciplex forming co-host system is employed to achieve highly efficient organic light- emitting diode (OLED) with good electroluminescent lifetime. The exciplex is formed at the interfacial contact of a conventional star-shaped carbazole hole-transporting material, 4, 4', 4 “-tris (N-carbazolyl)-triphenylamine (TCTA) and a novel triazine electron-transporting material, 2, 4, 6-tris [3-(1H-pyrazol-1-yl) phenyl]-1, 3, 5-triazine (3P-T2T). The excellent combination of TCTA and 3P-T2T is applied as co-host of a common green … ...Read More

Yea-Fen Jang, Tzu-Chun Lin, Jhih-Yan Guo, Chien-Ming Fan Chiang, Ming-Lun Wu, Hsin-Yi Shen, Tsung-Cheng Chen, Zu-Po Yang, Ya-Ju Lee, Hai-Ching Su, Chih-Hao Chang, Shun-Wei Liu

Abstract Solid-state light-emitting electrochemical cells (LECs) show several advantages over conventional organic light-emitting devices (OLEDs) such as simple device structure compatible with solution processes, low operation voltage and capability of utilizing inert cathode metals. However, device performance of LECs must be improved, eg enhancing light extraction, to meet the requirements for practical applications. Among the optical modes trapped in LECs, light trapped in substrate mode is easier to be extracted, eg, by simply …..Read More

Ko-Wei Chen, Li-Yen Lin, Yi-Hua Li, Ya-Ze Li, Thanh Phuc Nguyen, Sajal Biring, Shun-Wei Liu, Ken-Tsung Wong

Abstract Four new molecules with acceptor-donor-acceptor (ADA) configuration where cyclopenta [2, 1-b: 3, 4-b′] dithiophene (CPDT) as the electron-donating core connecting to cyano (CN)-substituted 2, 1, 3-benzothiaidiazole (BT) as electron-withdrawing end groups are reported. With the same acceptor CN-BT, we found that CPDT can serve as a better donor as compared to that of dithieno [3, 2-b: 2′, 3′-d] silole (DTS) to give stronger intramolecular charge transfer (ICT) character and therefore better light harvesting ability …..Read More

Jun Lin, Yang Wang, Premkumar Gnanasekaran, Yu‐Cheng Chiang, Chun‐Chieh Yang, Chih‐Hao Chang, Shih‐Hung Liu, Gene‐Hsiang Lee, Pi‐Tai Chou, Yun Chi, Shun‐Wei Liu

Abstract Bis-tridentate Ir (III) metal complexes are expected to show great potential in organic light-emitting diode (OLED) applications due to the anticipated, superb chemical and photochemical stability. Unfortunately, their exploitation has long been hampered by lack of adequate methodology and with inferior synthetic yields. This hurdle can be overcome by design of the first homoleptic, bis-tridentate Ir (III) complex [Ir (pzpyph)(pz H pyph)](1), for which the abbreviation (pzpyph) H (or pz H pyph) stands for the parent 2 …..Read More

Yuan Jay Chang, Jung-Lien Hsu, Yi-Hua Li, Sajal Biring, Tzu-Hung Yeh, Jhih-Yan Guo, Shun-Wei Liu

Abstract Fabrication of vacuum deposited small molecules organic solar cell with open- circuit voltage (V oc) exceeding 1 V is crucial in advancing the applications of organic photovoltaics (OPVs). Here, a novel carbazole-based donor-π bridge-acceptor (D-π-A) of p- type material (F-series) in combination with fullerene derivative C 60 or C 70 as n-type material for bulk-heterojunction OPVs with the structure of ITO/MoO 3 (15 nm)/F-series donor: C 60 or C 70 (40 or 80 nm)/BCP (7 nm)/Ag (120 nm) have been proposed. The …..Read More

Sajal Biring, Ya-Ze Li, Chih-Chien Lee, Arvind Pan, Gautham Kumar, Shun-Wei Liu

Abstract Pentacene based organic field effect transistors with polyvinyl phenol gate dielectric are fabricated by controlling the dielectric surface energy and grain size of the first monolayer of pentacene. In this work, we introduce a novel approach to tune the surface energy of the polymer dielectric. This is performed by baking the polymer dielectric, polyvinyl phenol, at different vacuum conditions at 160° C before the deposition of pentacene layer. After the deposition of pentacene, these devices exhibit dramatic improvement of carrier …..Read More

Jhih-Yan Guo, Yi-Hua Li, Chih-Chien Lee, Sajal Biring, Shun-Wei Liu

In this work, a novel time-of-flight (TOF) measurement was carried out by employing an ultra- thin charge generation layer (CGL) of chloroboron subphthalocyanine and C 60, which shows a highly absorption coefficient at 532 nm from Nd: YAG laser. This implies that the proposed CGL region can facilitate in generating huge number of charge carriers, ie holes or electrons in organic device under the pumping wavelength. Moreover, such CGL-TOF would significantly reduce the sample thickness to~ 100 nm compared to standard TOF …..Read More

Gautham Kumar, Sajal Biring, Yi-Nan Lin, Shun-Wei Liu, Chih-Hao Chang

Abstract We investigated an efficient organic light-emitting diodes (OLEDs) using an ultra- thin silver (Ag) anode, whereas Ag was deposited on a roughened glass substrate by laser patterning method. The thin-film property of this roughened silver anode exhibited an optical transmittance of more than 65% in visible light at 532 nm and a low electrical sheet resistance of 3.2 Ω/sq, which is superior to standard indium-tin-oxide (ITO) glass. Therefore, we report an ITO-free, exciplex-forming phosphorescent OLED showing Lambertian …..Read More

Anand Sharma, Nitesh Chourasia, Anumol Sugathan, Yogesh Kumar, Satyabrata Jit, Shun-Wei Liu, Anshu Pandey, Sajal Biring, Bhola Nath Pal

Li5AlO4, a well-known material for solid state electrolyte application, has never been considered hitherto as a gate dielectric of metal oxide thin film transistor (TFT). Here we demonstrate the salient features of Li5AlO4 as a gate dielectric outperforming the conventional inorganic dielectrics used in TFT. The high dielectric constant (k) of this insulator has been achieved by utilizing the improved capacitance contributed by the mobile lithium ion (Li+) within the dielectric film. We have synthesized this dielectric by cost …..Read More

Chih-Chien Lee, Chun-Jen Shih, Gautham Kumar, Sajal Biring, Somaditya Sen, Shun-Wei Liu

We propose a DC sputtering process to fabricate an indium-tin oxide (ITO) electrode with nano-pinhole morphology for an efficient exciplex organic light-emitting device (OLED). The ITO thin-film of 80 nm thickness sputtered at room temperature shows an optical transmittance of over 86.5% in the range of visible light and an electrical sheet resistance of 75 ohm sq− 1. A layer of di-[4-(N, N-ditolyl-amino)-phenyl] cyclohexane (HATCN) is inserted into the device to improve the hole injection efficiency by reducing the injection barrier at …..Read More

Yuan-Chih Lo, Hao-Chun Ting, Ya-Ze Li, Yi-Hua Li, Shun-Wei Liu, Kuo-Wei Huang, Ken-Tsung Wong

The synthesis, structure, and properties of three new 5, 6, 11, 12-tetraarylindeno [1, 2-b] fluorenes are reported. The highly twisted conformations between an indeno [1, 2-b] fluorene core and peripheral aryl substitutions endow these indeno [1, 2-b] fluorene derivatives with good photostability for use as electron donors for vacuum-deposited photovoltaic devices. The optimized device based on a TAInF2 donor blended with C70 a..Read More

Nasima Khatun, Parasmani Rajput, Dibyendu Bhattacharya, SN Jha, Sajal Biring, Somaditya Sen

Abstract The anatase to rutile phase transition of TiO 2 which normally occurs at 750° C, is reduced to temperatures below 600° C by vanadium doping. The structural transformation is observed by a systematic study in the temperature range from 450° C to 750° C. The introduction of vanadium in rutile lattice is found to have impact on lattice parameters and particle size. This substitution also helps to reduce the bandgap of rutile TiO 2 to 1.76 eV from 3.04 eV upon 6 at% of vanadium doping. Vanadium induces additional donor level …..Read More

Mohd Nasir, AK Bera, SM Yusuf, DK Shukla, Sunil Kumar, DM Phase, Shun-Wei Liu, Sajal Biring, Somaditya Sen

Abstract: Among multifunctional double perovskite oxides, La2NiMnO6 has recently drawn significant attention due to its rich physics and potential for device applications. The relative variation in Ni: Mn ratio strongly influences the structural, magnetic and electric properties of La2NiMnO6. In the present study, La2Ni1. 5Mn0. 5O6 with Ni: Mn= 3: 1 ratio is synthesized using sol-gel method. Modifications of the above physical properties are discussed. Rietveld analysis of X-ray diffraction data shows that La2Ni1. 5Mn0. 5O6 samples belong to a …..Read More

Tulika Srivastava, Gaurav Bajpai, Gyanendra Rathore, Sajal Biring, Somaditya Sen

Abstract: UV sensing in pure ZnO is due to oxygen adsorption/desorption process from ZnO surface. Vanadium doping improves UV sensitivity of ZnO. Enhancement in UV sensitivity in doped ZnO is attributed to trapping and de-trapping of electrons at V4+ & V5+-related defect states. An extra electron in the V4+ state is excited under UV illumination while in absence of the same a trapping happens at the V5+ state. An insight to the mechanism is obtained by an analytic study of the response phenomenon...Read More

Tulika Srivastava, Gaurav Bajpai, Nidhi Tiwari, Dibyendu Bhattacharya, SN Jha, Sunil Kumar, Sajal Biring, Somaditya Sen

Vanadium incorporation in ZnO modifies the lattice structure. The valence state of V plays an important role, controlling the oxygen content and thereby dimensions of the lattice. Both V4+ and V5+ are more electropositive than Zn2+ and reduce oxygen vacancies, resulting in lattice expansion. However, the sizes of both V4+ and V5+ are smaller than Zn2+, thereby resulting in the lattice contraction. The internal competition of increasing oxygen content and reducing effective crystal radius decides the lattice expansion and contraction. This …..Read More

Tulika Srivastava, Aswin Sadanandan, Gaurav Bajpai, Saurabh Tiwari, Ruhul Amin, Mohd Nasir, Sunil Kumar, Parasharam M Shirage, Sajal Biring, Somaditya Sen

Abstract Si addition in ZnO lattice significantly improves electrical conductivity. The extra charge of Si 4+ ion (in comparison to Zn 2+) attracts more oxygen in the lattice and reduces oxygen vacancies. Reduction of oxygen vacancies (defects) reduces strain in the lattice. Transparency of visible light (< 3.0 eV) improves due to reduction of these defects in the wide bandgap (~ 3.3 eV: UV) of ZnO. Extra charge of Si 4+ enhances carrier density in the ZnO lattice. Improved carrier density, reduced strain facilitate transport of carriers and …..Read More

Arun Kumar Yadav, Parasmani Rajput, Ohud Alshammari, Mahmud Khan, Gautham Kumar, Sunil Kumar, Parasharam M Shirage, Sajal Biring, Somaditya Sen

Abstract Recently interest in finding magnetoelectric coupling in Fe substituted PbTiO 3 is observed. Synthesis of single phase PbTi (1− x) Fe (x) O 3 is a challenge which we report for 0≤ x≤ 0.5. PbTiO 3 is a strong ferroelectric. Fe substitution at the Ti site may lead to a potential magnetoelectric multiferroic material maintaining the non-centrosymmetric lattice distortion due to elongation of Ti-O octahedral in PbTiO 3 intact. The synthesis chemistry is a determining factor on the pure phase. Valence state, size and coordination of substituting …..Read More

Arun Kumar Yadav, Anita Verma, Sunil Kumar, V Raghavendra Reddy, Parasharam M Shirage, Sajal Biring, Somaditya Sen

Abstract: PbTiO3 has the highest tetragonal distortion (c/a= 1.064) and highest spontaneous polarization among perovskite titanates. But, it is hazardous and hence one needs to reduce Pb content by substituting or reducing Pb content for use in applications. Pb (1-x)(K0. 5Sm0. 5) xTiO3 (0&x&0. 5) perovskite powders were synthesized by sol-gel process, where Pb2+ was replaced by a combination of K+ 10.5 Sm+ 30.5 (equivalent charge and comparable ionic radius) providing an excellent substitution model to study changes in structural and …..Read More

Saurabh Tiwari, Gaurav Bajpai, Tulika Srivastava, Srashti Viswakarma, Parasharam Shirage, Somaditya Sen, Sajal Biring

Abstract CeO 2, a strong cubic fluorite structured ceramic, with well-defined optical and mechanical properties may be modified by proper substitution. Ni substitution in Ce 1− x Ni x O 2 (0≤ x≤ 0.08) nanoparticles, hints at strain generation in the lattice bringing in changes in structural properties. The strain introduces changes in the electronic, optical and mechanical properties. The origin of strain is discussed using structural, optoelectronic, vibrational and mechanical studies discussing the elastic and plastic behavior of the …..Read More

SC Chuang CM Hsieh, YL Yu, CP Chen

Organic–inorganic lead halide perovskite solar cells (PSCs) offer a promising low-cost manufactural solar technology as they are compatible with large-scale and low-temperature (< 100° C) solution processes. Through the optimization of perovskite active layer and phenyl-C61-butyric acid methyl ester (PC61BM) layer thickness, the normal cells showed 9.7% power conversion efficiency (PCE). Compared with the corresponding normal devices, we observed an improvement in PCE from 9.7% to 11.3% and 10.2% for the devices …..Read More

CP Chen YY Yu, YJ Ting, CL Chung, TW Tsai

Abstract In this study, chemical treatment (CT; oxidation–reduction method) and physical treatment (HP; hot-pressing methods) were applied to improve the performance of silver nanowire (AgNW)-derived electrodes on a glass or flexible polyethylene terephthalate (PET) substrate. The four-point probe method, UV-Vis spectroscopy and scanning electron microscopy (SEM) were used to measure the properties of AgNW electrodes and compare them with those of indium tin oxide (ITO) electrodes for exploring the possibility of using …..Read More

Yu-Lung Weng, Yi-Chan Li, Chih-Ping Chen, Yuan Jay Chang

Abstract Six novel small molecules containing phenothiazine as the core moiety of p-type materials were synthesized in combination with PC 61 BM or PC 71 BM as n-type materials for bulk heterojunction organic photovoltaic (OPV) cells. Phenothiazine was used as donor building blocks to construct acceptor–donor–acceptor (A–D–A) and A–D–D–A small molecule. We investigated the relationship between the molecular structures, optoelectronic and thermal properties, and their blend film morphologies for OPV applications. We …..Read More

Ying-Chieh Chao, Shih-Chieh Yeh, Hsiang-Lin Hsu, Bing-Huang Jiang, Kuo-Hua Sun, Chin-Ti Chen, Chih-Ping Chen, Ru-Jong Jeng

Abstract In this study, we synthesized two emeraldicene (EMD)-based conjugated polymers, PBTEMD and PFEMD, through polymerization of 4, 7-di (thien-2-yl) benzo [c][1, 2, 5] thiadiazole and 9, 9-bis (2-ethylhexyl)-9H-fluorene, respectively. We then blended these EMD-derived polymers (as electron-donating materials) with [6, 6]-phenyl-C 71-butyric acid methyl ester (PC 71 BM) in the active layers of polymer solar cells (PSCs) and investigate their optoelectronic properties and related photovoltaic performance. To best of our …..Read More

Yang-Yen Yu, Tzung-Wei Tsai, Chun-Chen Yang, Chih-Ping Chen

Most efficient organic photovoltaic (OPV) devices are fabricated using halogenated solvents, which are hazardous and environmentally unfriendly. From an industrial perspective, green solvents are necessary for the roll-to-roll production of OPV modules. In this study, we fabricated nonfullerene (NF) OPV devices that are based on the blend films of PTB7-Th and 3, 9-bis (2-methylene-(3-(1, 1-dicyanomethylene)-indanone)-5, 5, 11, 11-tetrakis (4-hexylphenyl)-dithieno [2, 3-d: 2′, 3′-d′]-s-indaceno [1, 2-b: 5, 6-b′]-dithiophene (ITIC …..Read More

Yang-Yen Yu, Chien-Hsun Chen, Chu-Chen Chueh, Chun-Ying Chiang, Jang-Hsing Hsieh, Chih-Ping Chen, Wen-Chang Chen

In this study, a new hybrid electrode featuring a high gauge factor of> 30, decent stretchability (100% of the original conductivity can be retained after 50 cycles of stretching under a 20% strain without prestrain treatment), high transmittance (> 70%) across 400–900 nm, and a good sheet resistance (< 50 Ω sq–1) was successfully exploited. These superior properties were revealed to originate from the reversible phase separation endowed by the nanogranular-like morphology formed in Ag. Owing to such discrete nanomorphology, the …..Read More

Ching-Chih Chang, Bing-Huang Jiang, Yi-Chan Li, Chih-Ping Chen, Chien-Hong Cheng

Abstract Varying the structures of conjugated side chains can be an efficient approach toward tailoring the optoelectronic properties of conjugated polymers. In this study, we synthesized four indacenodithiophene (IDT)-based side chain conjugated donor–acceptor alternating polymers. We introduced four different acceptor units (difluorobenzothiadizole: PIDTHT-FBT; difluoroquinoxaline: PIDTHT-QF; dicyanoquinoxaline: PIDTHT-QCN; diketopyrrolopyrrole: PIDTHT-DPP) to study the effects of the conjugated side chains on …..Read More

Chien-Tien Chen, Fang-Yuan Tsai, Chun-Ying Chiang, Chih-Ping Chen

A spiro core appended with trithiophene arms and α-cyanoacrylate end groups was used for the first time in bulk heterojunction solar cell applications. The resulting device performance was evaluated by its blending with PC61BM, leading to a short-circuit current density (J sc) of 3.55 mA cm–2 which was 2.4 and 6.6 times better than those of the open form and nonspiro core analogs. The 1, 8-diiodooctane solvent additive suppressed its microcrystalline self-aggregation, leading to a well-defined blend film morphology with …..Read More

Chih-Ping Chen, Chun-Ying Chiang, Yang-Yen Yu, Yu-Sheng Hsiao, Wen-Chang Chen

Abstract Electronic skins and smart textiles are emerging applications integrating wearable displays, smart sensing systems, health-care monitors, and stretchable power systems. Although various deformable optoelectronic devices have been demonstrated, high-performance stretchable photovoltaic (PV) devices remain a significant challenge in device engineering and materials optimization. In this paper, we demonstrate how a ubiquitous material—3 M™ tape—can be used as a transparent substrate for highly efficient …..Read More

Jong‐Hong Lu, Yi‐Hung Lin, Bing‐Huang Jiang, Chun‐Hung Yeh, Jui‐Chih Kao, Chih‐Ping Chen

Abstract High-performance colored aesthetic semitransparent organic photovoltaics (OPVs) featuring a silver/indium tin oxide/silver (Ag/ITO/Ag) microcavity structure are prepared. By precisely controlling the thickness of the ITO layer, OPV devices exhibiting high transparency and a wide and high-purity color gamut are obtained: blue (B), green (G), yellow-green (YG), yellow (Y), orange (O), and red (R). The power conversion efficiencies (PCEs) of the G, YG, and Y color devices are greater than 8%(AM 1.5 G irradiation, 100 …..Read More

Bing-Huang Jiang, Ya-Juan Peng, Chih-Ping Chen

In this study, we have found that interfacial layers (IFLs) based on Jeffamines (industrial polyetheramine derivatives) can improve the performance of organic photovoltaics (OPVs). We evaluated four different Jeffamines (average molecular weight: 2000 g mol− 1)—M2005, M2070, D2000, and ED2003—having either a monoamine or diamine structure and various ratios of propylene oxide (PO) and ethylene oxide (EO) for their suitability as IF materials for OPV applications. The presence of the Jeffamine altered the work function of ZnO and …..Read More

Hoang Chinh Nguyen, Shih-Hsiang Liang, Thien Thanh Doan, Chia-Hung Su, Pei-Cheng Yang

Abstract Black soldier fly larvae (BSFL), oleaginous insects, can assimilate several organic wastes for fat accumulation, thus serving as a promising feedstock for biodiesel production. In this study, the transesterification of BSFL fat and methanol was catalyzed using lipases to produce environmentally friendly biodiesel. Different commercial lipases were evaluated for their catalytic activity in the reaction. Among the examined biocatalysts, Novozym 435, an immobilized enzyme, showed the highest activity level. Response surface methodology was subsequently used to optimize the lipase-catalyzed reaction and to develop a reliable empirical model for prediction. A maximum biodiesel yield of 96.18% was obtained at a temperature of 26 C, methanol: fat molar ratio of 6.33, enzyme loading of 20%, and reaction time of 9.48 h. Under the optimal reaction conditions and enzyme regeneration process …..Read More

Hoang Chinh Nguyen, Szu-Pei Wu, Chia-Hung Su, Tzann-Shun Hwang

Résumé Description du sujet. Les phosphatases alcalines (APases) sont fréquemment employées comme marqueurs non radioactifs pour la détection spécifique de protéines ou d'ADN cibles en médecine clinique et en biologie moléculaire. Toutefois, leur application en biotechnologie industrielle nécessite une bonne stabilité tant thermique que de conservation. Nos recherches préliminaires ont montré que l'APase de Thermus sp. NTU- 237 (TsAPase) est thermostable et présente une haute activité. Il est donc intéressant d'établir les conditions optimales de son emploi. Objectifs. Caractériser l'APase de la souche thermophile Thermus sp. NTU-237 et évaluer ses potentialités d'application. Méthode. Le gène de l'APase de Thermus sp. NTU-237 a été cloné pour être exprimé dans Escherichia coli. Cela a permis l'étude des effets sur l'activité enzymatique TsAPase, de la …..Read More

Fu Ming Wang, Sylvia Ayu Pradanawati, Nan-Hung Yeh, Shih-Chang Chang, Ya-Tang Yang, Shih-Han Huang, Ping-Ling Lin, Jyh-Fu Lee, Hwo-Shuenn Sheu, Meng-Lin Lu, Chung-Kai Chang, Alagar Ramar, Chia-Hung Su

Electric vehicles (EVs) are poised to dominate the next generation of transportation, but meeting the power requirements of EVs with lithium ion batteries is challenging because electrolytes containing LiPF6 and carbonates do not perform well at high temperatures and voltages. However, lithium benzimidazole salt is a promising electrolyte additive that can stabilize LiPF6 through a Lewis acid–base reaction. The imidazole ring is not eligible for high-voltage applications owing to its resonance structure, but in this research, electron- withdrawing (− CF3) and electron-donating (− CH3) substitutions on imidazole rings were investigated. According to the calculation results, the CF3 substitution facilitates a high electron cloud density on imidazole ring structures to resist the electron releases from bezimidazole in oxidation reactions. In addition, through CF3 substitution, electrons are …..Read More

Chia-Hung Su, Govindarajan Venkat Kumar, Shritama Adhikary, Palaniyandi Velusamy, Kannaiyan Pandian, Periasamy Anbu

Abstract There is a vital need for the production of clean, hygienic, and antibacterial textile fabric for use as hospital clothing, surgical scrubs and linens to protect against nosocomial pathogens. In the present study, cotton fabrics were treated with sodium alginate-capped silver nanoparticles and were tested for antibacterial activity against nosocomial pathogens. The sodium alginate-capped silver nanoparticles were synthesized under various experimental conditions by using varying sodium alginate concentrations (0.5–2%), volumes of reducing agent aniline (50, 100, 150 μL), and durations of heat treatment (30–240 s). The synthesized nanoparticles were characterized using ultraviolet-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Furthermore, the antibacterial efficacy of sodium alginate-capped silver nanoparticles …..Read More

Chia Hung Su, Palaniyandi Velusamy, Govindarajan Venkat Kumar, Shritama Adhikary, Kannaiyan Pandian, Periyasamy Anbu

Abstract In the present study, a simple method to impregnate silver nanoparticles (AgNPs) into carboxymethyl cellulose (CMC) and sodium alginate (SA) is reported for the first time. Single step synthesis of carboxymethyl cellulose (CMC) and sodium alginate (SA) biopolymer protected silver nanoparticles (AgNPs) using aniline as a reducing agent under reflux conditions was investigated. The synthesized nanoparticles were characterized by UV– Vis spectrophotometry, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The FESEM results of CMC@ AgNPs and SA@ AgNPs showed the formation of spherical nanoparticles sized 30– 60 nm. Testing of the antibiofilm efficacy of the polymer protected AgNPs against different bacterial strains such as Klebsiella pneumoniae MTCC 4032 and Streptococcus …..Read More

Thi My Huong Dinh, Chia Hung Su

Tóm tắt: Nhiên liệu sinh học là một nguồn nhiên liệu tái tạo, được sản xuất thông qua quá trình chuyển ester hóa dầu thực vật, mỡ động vật, hay quá trình este hóa axit béo và ancol mạch ngắn (metanol, etanol, propanol and butanol) với sự có mặt của các loại xúc tác axit, bazo vô cơ hoặc enzyme. Nghiên cứu ảnh hưởng của các điều kiện tiến hành quá trình este hóa axit béo với methanol để sản xuất dầu sinh học bằng chất xúc tác là enzyme lỏng với chất siêu hấp thụ (SAP) nhằm mục đích xác định các giá trị tối ưu của các yếu tố ảnh hưởng đến quá trình phản ứng bao gồm nhiệt độ, tỉ lệ mol chất phản ứng, hàm lượng chất xúc tác và SAP. Kết quả nghiên cứu cho thấy rằng ở nhiệt độ 45ºC, tỉ lệ mol giữa axit béo và methanol là 1: 3, hàm lượng xúc tác và SAP đã sử dụng là 10% khối lượng acid thì hiệu suất phản ứng đạt giá trị cao nhất gần 90% sau 6 giờ phản ứng...Read More

Hoang Chinh Nguyen, Szu-Pei Wu, Chia-Hung Su, Tzann-Shun Hwang

(1) Ton Duc Thang University. Faculty of Applied Sciences. 19 Nguyen Huu Tho St. Tan Phong Ward. Dist. 7. Ho Chi Minh City 700000 (Vietnam). (2) Yuanpei University. Department of Biotechnology and Pharmaceutical Technology. 306 Yuanpei St. Xiangshan, Hsinchu City 30015 (Taiwan). (3) Ming Chi University of Technology. Graduate School of Biochemical Engineering. 84 Gungjuan Rd. Taishan, Taipei 24301 (Taiwan). Email: chsu@mail.mcut.edu.tw (4) Chinese Culture University. Graduate Institute of Biotechnology. 55 Hwa-Kang Rd. Yang-Ming-Shan. Taipei 11114 (Taiwan). E-mail: hzx@faculty.pccu.edu.tw … Description of the subject. Alkaline phosphatases (APases) are commonly used as nonradioactive markers for detecting specific proteins or DNA targets in clinical medicine and molecular biology. However, their applications in the biotechnology industry require thermostability and storage stability. Our preliminary study revealed that …..Read More

Cheng-Shane Chu, Zhi-Ren Su

This paper presents a ratiometric optical broad range pH sensor that comprises an optical fiber coated at one end with CdSe/ZnS quantum dots (QDs) and Oxazine 170 perchlorate (O170) embedded in ethyl cellulose (EC) matrix. The feasibility of coating an optical fiber with the sensing film to fabricate a ratiometric fiber optic broad range pH sensor is investigated. Using an LED with a central wavelength 405 nm as an excitation light source, the CdSe/ZnS QDs shows that the fluorescence intensity at 575 nm decreases with increasing pH and O170 shows the fluorescence intensity at 655 nm increases with increasing pH. The ratio of fluorescence intensities at 575 nm and 655 nm has a linear relationship with pH value in the 1.6-13.2 range. The ratiometric sensing approach presented in this study has the advantage of suppressing spurious fluctuations in the …..Read More

Cheng-Shane Chu, Yen-Fu Chen

A simple, low cost technique to fabricate a ratiometric optical fiber ammonia (NH 3) sensor has been presented. The ratiometric optical fiber ammonia sensor was based on the ammonia induced absorbance change of sensing material Oxazine 170 perchlorate (O170) in ethyl cellulose (EC) with the luminescence intensity of 7-amino-4-trifluoromethyl coumarin (AFC). The observed luminescence intensity from AFC at 487 nm decreased with increasing the ammonia concentration. The sensitivity of optical ammonia sensor is quantified in terms of the ratio I 0/I 100, where I 0 and I 100 represent the detected luminescence intensities in nitrogen and 1000 ppm ammonia concentration, respectively. The experimental result shows that the sensitivity of the ratiometric optical fiber ammonia sensor is estimated to be 1.44. The sensitive optical ammonia sensor based on fluorescence intensity changes of …..Read More

Cheng-Shane Chu, Meng-Wei Hsieh

A new optical carbon dioxide sensor based on the colormetric change of pH indicator a- naphtholphthalein with the internal reference fluorescent CIS/ZnS quantum dots (QDs) was developed. The luminescence intensity of CIS/ZnS QDs increased with increasing carbon dioxide concentration. The sensing films consisting of a-naphtholphthalein in polyIBM and CIS/ZnS QDs in polystyrene layer. The sensitivity of optical carbon dioxide sensor is quantified in terms of the ration I 100/I 0, where I 100 and I 0 represent the detected luminescence intensities in pure carbon dioxide and pure nitrogen environments, respectively. The experimental result reveals that the new optical carbon dioxide sensor has sensitivity of I 100/I 0= 13.4...Read More

Cheng-Shane Chu, Jhih-Jheng Syu

An optical sensor for the dual sensing of oxygen (O_2) and carbon dioxide (CO_2) based on sensing films coated on filter paper is proposed. Ethyl cellulose (EC) doped with platinum (II) meso-tetrakis (pentafluorophenyl) porphyrin (PtTFPP) and 7-amino-4-trifluoromethyl coumarin serve as the oxygen sensing material and reference blue emission dye for the pH indicator, respectively. The CO_2 sensing layer includes the pH-sensitive fluorescent indicator 1-hydroxy-3, 6, 8-pyrenetrisulfonic acid trisodium salt immobilized within the EC. The O_2-and CO_2-sensitive materials can both be excited with a 405 nm LED, and the two emission wavelengths can be detected separately. The experimental result reveals that the optical O_2 and CO_2 sensors have sensitivities of I_N_2/I_100% O_2= 22.8 and I_N_2/I_100% CO_2= 3.6, respectively. The response times of the optical O_2 sensor …..Read More

Ming-Hung Chen

Abstract This paper is concerned with the design and implementation of the closed-loop controller with current sensors for brushless DC motor drives to yield good speed regulation, low current harmonic and stable output speed. The design of the controller is conducted by digitizing the mathematical model of brushless DC motors. The regulation and limitation of control parameters are also studied. The saliency of brushless DC motor yields larger quadrature-axis inductance than that of the direct-axis. This results in reluctance torque accordingly. By appropriately adjusting the direct-axis current, the reluctance torque can be controlled to achieve high-efficiency operation. The proposed control strategy will not only yield optimal efficiency but also result in the immunity of performance to the variation of machine parameters. A predicted current estimator is proposed to function under …..Read More

Hung-Ing Chen, Jui-Ju Hsiao, Chia-Hui Fang, Joe-Air Jiang, Jen-Cheng Wang, Ya-Fen Wu, Tzer-En Nee

Abstract The characteristics of the photocarrier transfer process in ZnO nanostructures fabricated on silicon substrates by the hydrothermal method are studied using temperature- dependent photoluminescence (PL) measurements. The luminescence shows distinct features arising from the dynamics of the excited carriers which occur as a consequence of the different size distributions of the ZnO nanostructures. It is found that the temperature- dependent photoluminescence phenomena can be attributed to the carrier-thermalization processes that occur in the ZnO nanostructures. The photogenerated carrier redistribution leads to a blueshift in the emission energy of the radiative transitions in the ZnO nanostructures. The random configuration of the photogenerated carriers in the ZnO nanostructures can be qualitatively understood in terms of the transition enthalpy and the …..Read More

Yi Chen, Wei-You Chen, Hung-Pin Hsu, Jiunn-Chyi Lee, Ya-Fen Wu

Abstract In this work, the hydrothermally grown ZnO nanostructures were successfully prepared on indium tin oxide glass using different aqueous solution molarities. The effect of solution molarity on the structual and optical properties of ZnO nanostructures were studied by X-ray diffraction and temperature-dependent photoluminescence (PL) measurements. The PL intensity ratio of the ultraviolet emission to the visible emission is also calculated. It is found that the crystal quality and the optical properties are improved by raising the solution molarity, but too higher solution molarity should lead to the disorder of ZnO structures, and deteriorate the crystal quality...Read More

Ya-Fen Wu, Jiunn-Chyi Lee

Abstract: We introduced multiquantum-barrier (MQB) nanostructures into the barrier layers of InGaN/GaN multiquantum-well (MQW) heterostructures to improve the operation characteristics of the light-emitting devices. The electroluminescence (EL) spectra were examined over a broad range of temperatures for the samples. We observed inhibited carrier leakage for the sample with the MQB nanostructures. Greater inhomogeneity of nanocrystallite size and a stronger localization effect were also observed for the sample. To interpret this phenomenon, high-resolution X-ray diffraction curves were measured and analyzed using the Warren–Averbach model. External quantum efficiency as a function of temperature was also evaluated. The calculation results correspond with the inference the EL measurements provided. We determined that the performance of the light-emitting …..Read More

Bing-Yuh Lu, Ming-Kwen Tsai, Jhen-Chen Wang, Meng-Lun Hsueh, Huey-Dong Wu, Jin-Shin Lai, Ya-Fen Wu, Tzer-En Nee

Abstract: The sound of the siren of the ambulance is for the safety of the road transportation, but interferes the auscultation of the lung and heart sounds. The system implementation is included by (1) ACER Aspire 17 notebook as a server in right side;(2) HwaWei Amazing A6 smart mobile as a hot point in the middle; and (3) ACER Aspire 5 notebook as a client which the settings include IP address of host computer, and client, read and, write privileges of the data sockets, and running of NI data socket manager, and data socket server. Therefore, the parameters in the real-time DAS are verified as the better ones to prepare for the services on the ambulance...Read More

Ya Fen Wu, Jiunn Chyi Lee

Quaternary AlInGaN/AlInGaN multiquantum-well (MQW) structures were grown by metal- organic vapour-phase epitaxy (MOVPE). The influence of QW pairs and QW barrier width on the optical properties of the samples is investigated by means of temperature and incident- power dependent photoluminescence (PL) measurements. The PL emission peaks redshift and the PL peak intensities increase as the number of QW pairs increases. On the other side, a blueshift of the PL peak energy and reduction of the PL peak intensity are observed for the sample with thinner barrier width. These results are explained by carrier localization effect. The S-shaped temperature-dependence of the PL peak energies indicates the existence of localized states induced by the potential fluctuations. The estimated degree of localization effect is found to be enhanced for the sample with more QW pairs and thicker …..Read More

Tzu-Hung Yeh, Chih-Chien Lee, Chun-Jen Shih, Gautham Kumar, Sajal Biring, Shun-Wei Liu

We report a highly efficient transparent and inverted organic light-emitting diode (OLED) with a vacuum-deposited MoO 3 (5 nm)/Ag (12 nm)/WO 3 (40 nm)(MAW) multilayered electrode having a low sheet resistance of 4.2 Ω/sq, an average transmittance of 88% at a wavelength of 500–550 nm, and a smooth morphology with a root-mean-square roughness of 0.339 nm. The inverted phosphorescent OLED with MAW anode exhibits a total (sum of the bottom and top emissions) maximum power efficiency of 62.1 lm/W and an external quantum efficiency of 20.1%. In addition, the transparent device can achieve almost equal bottom-to-top emission ratio of 1: 1.1 and a total transmittance of> 80% in the visible-light range. The better device performance arises from the transparent MAW electrode acting as a capping layer to modulate the bottom/top emission direction and the optical properties of the device...Read More

Tulika Srivastava, Gaurav Bajpai, Shun Wei Liu, Sajal Biring, Somaditya Sen

Abstract Effect of different wavelengths (350, 380, 390, 400, 450, 550 & 650 nm) of light on surface conductivity of sol-gel synthesized Zn 1− x Si x O material has been observed. Enhancement in conductivity at all wavelengths of light had been attributed to enhanced charge carrier concentration with silicon doping. Reduction in sensitivity for UV and visible light wavelength indicates reduction of surface defects and deep level traps with Si 4+ incorporation. Enhanced photo stability with Si 4+ doping makes it an appropriate material for transparent electrodes used in various display and electronic devices...Read More

Anita Verma, Arun Kumar Yadav, Sunil Kumar, Velaga Srihari, Parasmani Rajput, V Raghavendra Reddy, Ravindra Jangir, Himanshu K Poshwal, Shun Wei Liu, Sajal Biring, Somaditya Sen

A detailed study was carried out to investigate the effects of poling on structure, vibrational, dielectric, and ferroelectric properties of donor-doped (V5+ at Ti4+-site) lead-free Na0. 47Bi0. 47Ba0. 06Ti (1-x) VxO3,(x= 0, 0.01, and 0.03) ceramics fabricated via a modified sol- gel method. Rietveld refinement of synchrotron radiation source powder x-ray diffraction data showed that unpoled samples are in rhombohedral R3c phase whereas poled samples showed a mix rhombohedral R3c and tetragonal P4mm phases at ambient temperature, due to a long-range order established in lattice system after poling. V+ 5 doping increases the rhombohedral distortion in unpoled and poled samples while it reduces the tetragonality in poled samples. Vibrational study revealed that unpoled samples have more lattice disorder compared to poled samples. X-ray absorption near edge spectroscopy measurement …..Read More

Anita Verma, Arun Kumar Yadav, Nasima Khatun, Sunil Kumar, Ravindra Jangir, Velaga Srihari, V Raghavendra Reddy, Shun Wei Liu, Sajal Biring, Somaditya Sen

The structural, dielectric and ferroelectric properties of lead-free (Na0. 5-xKxBi0. 5-xLax) TiO3 powders synthesized by sol-gel self-combustion method were investigated. Rietveld refinement of Synchrotron x-ray diffraction data confirms pure single phase rhombohedral crystal structure with R3c space group for all the compositions and anti-phase octahedral tilting angle decreased with increase in composition x. Homogeneity and elemental proportions were confirmed by Energy dispersive x-ray spectrometry. The temperature- dependent dielectric study has shown two diffuse type of dielectric anomaly for all the samples, due to A-site disorder in the lattice, which has been assigned to two-has transitions: ferroelectric to anti-ferroelectric and anti-ferroelectric to the paraelectric phase transition. The transition temperature of these phase transitions is found to decrease as a …..Read More

Shun-Wei Liu, Sajal Biring, Ya-Ze Li, Ken-Tsung Wong

A novel up‐conversion device for NIR image sensing is proposed by integrating the OLED, OPV, and transparent electrodes. The proposed device captures NIR light reflected from the object and forms a real‐time image at the visible wavelengths on the OLED display with the image quality of> 600 dpi...Read More

Tulika Srivastava, Gaurav Bajpai, Gyanendra Rathore, Shun Wei Liu, Sajal Biring, Somaditya Sen

The UV sensing in pure ZnO is due to oxygen adsorption/desorption process from the ZnO surface. Vanadium doping improves the UV sensitivity of ZnO. The enhancement in UV sensitivity in vanadium-substituted ZnO is attributed to trapping and de-trapping of electrons at V4+ and V5+-related defect states. The V4+ state has an extra electron than the V5+ state. A V4+ to V5+ transformation happens with excitation of this electron to the conduction band, while a reverse trapping process liberates a visible light. An analytic study of response phenomenon reveals this trapping and de-trapping process...Read More

Arun Kumar Yadav, Anita Verma, Sunil Kumar, Velaga Srihari, AK Sinha, V Raghavendra Reddy, Shun Wei Liu, Sajal Biring, Somaditya Sen

The phase purity and crystal structure of Pb (1-x) LaxTi (1-x) AlxO3 (0≤ x≤ 0.25) samples (synthesized via the sol-gel process) were confirmed using synchrotron x-ray powder diffraction (XRD)(wavelength, λ= 0.44573 Å). Rietveld analyses of powder x-ray diffraction data confirmed the tetragonal structure for compositions with x≤ 0.18 and cubic structure for the sample with x= 0.25. Temperature-dependent XRD was performed to investigate the structural change from tetragonal to cubic structure phase transition. Raman spectroscopy at room temperature also confirmed this phase transition with compositions. Field emission scanning electron microscopy (FESEM) provided information about the surface morphology while an energy dispersive x-ray spectrometer attached with FESEM confirmed the chemical compositions of samples. Temperature and frequency dependent dielectric studies …..Read More

Tulika Srivastava, Gaurav Bajpai, Gyanendra Rathore, Prashant Mishra, Shun Wei Liu, Sajal Biring, Somaditya Sen

ZnO is co-doped with Na+ and Si4+ in the ratio 2: 1. The ratio was intentionally chosen so that net valence state of dopant theoretically matches that of host. This is to avoid dependence in the amount of oxygen vacancies/interstitials arising out of cationic valence state of the dopant. With such a combination, modifications in structural and optical properties do not depend on excess or deficit of the dopant charge state. For lower doping, Na+ ions behave as interstitial sites which enhance strain, lattice disorder and thereby creating defects. Formation of interstitial defects leads to reduction in bandgap energy and produce orange-red luminescence. For higher doping, Na+ starts substituting at Zn2+ site which helps in reducing strain and lattice disorder and thereby increases bandgap. Inspite of presence of Si4+ with higher charge, there is a gradual increase in oxygen vacancies due …..Read More

Arun Kumar Yadav, Anita Verma, Birender Singh, Deepu Kumar, Sunil Kumar, Velaga Srihari, Himanshu K Poshwal, Pradeep Kumar, Shun-Wei Liu, Sajal Biring, Somaditya Sen

Structural, vibrational and dielectric properties of (Pb1-xBix)(Ti1-xMnx) O3 (PBTM)(0 x 0.50) polycrystalline ceramics have been examined as a function of temperature. Synchrotron- based powder x-ray diffraction was employed to confirm phase purity and crystal structure of samples. Tetragonality (c/a ratio) of the PBTM system exhibit an increase 1.065, 1.066 for x= 0.06 and 0.09 compositions respectively, compare to 1.064 for x= 0 sample. Curie point was found~ 763 K and 773 K for x= 0.06 and 0.09 samples respectively. Though, tetragonality start to decreasing from samples with x 0.18, Curie point of the samples started decreasing for x 0.12. Temperature-dependent x-ray diffraction reveals the structural change from tetragonal to cubic structure. Unit cell volume was found to decrease with increasing temperature; indicate these materials are negative thermal expansion type until phase …..Read More

A Venkateswararao, Shun-Wei Liu, Ken-Tsung Wong

In organic solar cells (OSCs), the electron donor (D) and electron acceptor (A) blended active layer is the most crucial component for governing the power conversion efficiency (PCE). Various efficient donor materials with wide structural variations have been developed to couple with high-electron mobility fullerene-based acceptors, giving PCEs beyond 12%. However, fullerene-embedded OSCs encounter great challenges of low flexibility for structural modifications, poor absorption and blend morphological stability. The demand for alternative acceptors drives current OSC research towards non-fullerene acceptors (NFAs). Tailor-made NFAs of polymer or small molecule (SM) can typically exhibit tunable optical and electrochemical properties, high solubility, air stability, and favorable intermolecular interactions leading to compact packing and good nano-phase segregation in the active …..Read More

Chun-Jen Shih, Chih-Chien Lee, Ying-Hao Chen, Sajal Biring, Gautham Kumar, Tzu-Hung Yeh, Somaditya Sen, Shun-Wei Liu, Ken-Tsung Wong

An exciplex forming cohost system is employed to achieve a highly efficient organic light- emitting diode (OLED) with good electroluminescent lifetime. The exciplex is formed at the interfacial contact of a conventional star-shaped carbazole hole-transporting material, 4, 4′, 4 ″-tris (N-carbazolyl)-triphenylamine (TCTA), and a triazine electron-transporting material, 2, 4, 6-tris [3-(1 H-pyrazol-1-yl) phenyl]-1, 3, 5-triazine (3P-T2T). The excellent combination of TCTA and 3P-T2T is applied as the cohost of a common green phosphorescent emitter with almost zero energy loss. When Ir (ppy) 2 (acac) is dispersed in such exciplex cohost system, OLED device with maximum external quantum efficiency of 29.6%, the ultrahigh power efficiency of 147.3 lm/W, and current efficiency of 107 cd/A were successfully achieved. More importantly, the OLED device showed a low-efficiency roll-off and an …..Read More

Anand Sharma, Nitesh K Chourasia, Anumol Sugathan, Yogesh Kumar, Satyabrata Jit, Shun-Wei Liu, Anshu Pandey, Sajal Biring, Bhola N Pal

Li5AlO4, a well-known material for solid state electrolyte application, has never been considered hitherto as a gate dielectric of metal oxide thin film transistors (TFTs). Here we demonstrate the salient features of Li5AlO4 as a gate dielectric outperforming the conventional inorganic dielectrics used in TFTs. The high dielectric constant (k) of this insulator has been achieved by utilizing the improved capacitance contributed by mobile lithium ions (Li+) within the dielectric film. We have synthesized this dielectric via a cost- effective sol–gel method followed by a low-temperature annealing process yielding three phases such as amorphous-Li5AlO4 (a-Li5AlO4), α-Li5AlO4, and β-Li5AlO4 under different annealing conditions. Optimized TFTs fabricated with all of these three phases of Li5AlO4 on top of a highly doped silicon (p++-Si) wafer and a solution processed semiconducting …..Read More

Ko-Wei Chen, Li-Yen Lin, Yi-Hua Li, Ya-Ze Li, Thanh Phuc Nguyen, Sajal Biring, Shun-Wei Liu, Ken-Tsung Wong

Four new molecules with acceptor-donor-acceptor (ADA) configuration where cyclopenta [2, 1-b: 3, 4-b′] dithiophene (CPDT) as the electron-donating core connecting to cyano (CN)- substituted 2, 1, 3-benzothiaidiazole (BT) as electron-withdrawing end groups are reported. With the same acceptor CN-BT, we found that CPDT can serve as a better donor as compared to that of dithieno [3, 2-b: 2′, 3′-d] silole (DTS) to give stronger intramolecular charge transfer (ICT) character and therefore better light harvesting ability. The number and orientation of F-substitution on the BT ring, giving a clear structure-property relationship, can subtly manipulate the physical characteristics. These ADA type molecules were employed as electron donor in conjunction with C 70 as the electron acceptor in vacuum-deposited bulk heterojunction (BHJ) small-molecule organic solar cells (SMOSCs). Among them, the …..Read More