Browsing by Author "Wu, Cheng-En"

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A Pentacyclic Nitrogen-Bridged Thienyl-Phenylene-Thienyl Arene for Donor-Acceptor Copolymers: Synthesis, Characterization, and Applications in Field-Effect Transistors and Polymer Solar Cells
(2012-09-01)
Tseng, Cheng-An
;
Wu, Jhong-Sian
;
Lin, Tai-Yen
;
Kao, Wei-Shun
;
Wu, Cheng-En
A pentacyclic benzodipyrrolothiophene (BDPT) unit, in which two outer thiophene rings are covalently fastened with the central phenylene ring by nitrogen bridges, was synthesized. The two pyrrole units embedded in BDPT were constructed by using one-pot palladium-catalyzed amination. The coplanar stannylated Sn-BDPT building block was copolymerized with electron-deficient thieno[3,4-c]pyrrole-4,6-dione (TPD), benzothiadiazole (BT), and dithienyl-diketopyrrolopyrrole (DPP) acceptors by Stille polymerization. The bridging nitrogen atoms make the BDPT motif highly electron-abundant and structurally coplanar, which allows for tailoring the optical and electronic properties of the resultant polymers. Strong photoinduced charge-transfer with significant band-broadening in the solid state and relatively higher oxidation potential are characteristic of the BDPT-based polymers. Poly(benzodipyrrolothiophene-alt-benzothiadiazole) (PBDPTBT) achieved the highest field-effect hole mobility of up to 0.02 cm2?V-1?s-1. The photovoltaic device using the PBDPTBT/PC71BM blend (1:3, w/w) exhibited a Voc of 0.6 V, a Jsc of 10.34 mA?cm-2, and a FF of 50?%, leading to a decent PCE of 3.08?%. Encouragingly, the device incorporating poly(benzodipyrrolothiophene-alt-thienopyrrolodione) (PBDPTTPD)/PC71BM (1:3, w/w) composite delivered a highest PCE of 3.72?%. The enhanced performance arises from the lower-lying HOMO value of PBDPTTPD to yield a higher Voc of 0.72 V.
ALM: An adaptive location management scheme for approximate location queries in wireless sensor networks
(2010-10-15)
Yeh, Lo-Yao
;
Huang, Chen-Che
;
Wu, Cheng-En
;
Huang, Jiun-Long
;
資訊工程學系
Location management is an important issue for object tracking applications of wireless sensor networks. Since locations obtained by most positioning techniques are inherently imprecise, users may send approximate location queries with precision constraints to trade for energy consumption of sensor nodes. Therefore, we propose an Adaptive Location Management scheme called ALM to process approximate location queries. ALM employs a two-tier storage architecture (i.e., centric storage node and local storage node) to facilitate approximate query resolving and to reduce the energy consumption of sensor nodes. We propose a storage node relocation and replication mechanism, which can create, remove replicas of storage nodes and adjust the positions of storage nodes according to the location queries and updates. As such, the number of forwarding location update and query messages is reduced by the proposed storage node relocation and replication mechanism, thereby conserving more energy. The experimental results show that compared with EASE (Xu et al. (2008) [18]), ALM is able to reduce the number of transmission messages and the energy consumption of sensor network, and prolong the network lifetime. (C) 2010 Elsevier B.V. All rights reserved.
ALM: An adaptive location management scheme for approximate location queries in wireless sensor networks
(2010-10-15)
Yeh, Lo-Yao
;
Huang, Chen-Che
;
Wu, Cheng-En
;
Huang, Jiun-Long
;
資訊工程學系
Location management is an important issue for object tracking applications of wireless sensor networks. Since locations obtained by most positioning techniques are inherently imprecise, users may send approximate location queries with precision constraints to trade for energy consumption of sensor nodes. Therefore, we propose an Adaptive Location Management scheme called ALM to process approximate location queries. ALM employs a two-tier storage architecture (i.e., centric storage node and local storage node) to facilitate approximate query resolving and to reduce the energy consumption of sensor nodes. We propose a storage node relocation and replication mechanism, which can create, remove replicas of storage nodes and adjust the positions of storage nodes according to the location queries and updates. As such, the number of forwarding location update and query messages is reduced by the proposed storage node relocation and replication mechanism, thereby conserving more energy. The experimental results show that compared with EASE (Xu et al. (2008) [18]), ALM is able to reduce the number of transmission messages and the energy consumption of sensor network, and prolong the network lifetime. (C) 2010 Elsevier B.V. All rights reserved.
Di(4-methylphenyl)methano-C(60) Bis-Adduct for Efficient and Stable Organic Photovoltaics with Enhanced Open-Circuit Voltage
(2011-09-13)
Cheng, Yen-Ju
;
Liao, Ming-Hung
;
Chang, Chih-Yu
;
Kao, Wei-Shun
;
Wu, Cheng-En
A new class of fullerene bis-adducts di(4-methyl-phenyl)methano-C(60) bis-adduct (DMPCBA), di(4-fluorophenyl)methano-C(60) bis-adduct (DFPCBA), and diphenylmethano-C(60) bis-adduct (DPCBA) were rationally designed and easily synthesized. Compared to the lowest unoccupied molecular orbital (LUMO) energy level of PC(61)BM (-3.95 eV), the double functionalization effectively raises the LUMO energy levels of these fullerene materials to ca. -3.85 eV, regardless of the substituent groups (CH(3)-, F-, and H-) at the para-position of the phenyl rings. This phenomenon suggests that the plane of the phenyl groups is preferentially parallel to the fullerene surface, leading to poor orbital interactions with C(60) and negligible electronic effect. Importantly, such geometry sterically protects and shields the core C(60) structure from severe intermolecular aggregation, rendering it intrinsically soluble, morphologically amorphous, and thermally stable. The device based on the P3HT:DMPCBA blend exhibited an open-circuit voltage (V(oc)) of 0.87 V, a short-circuit current density (J(sc)) of 9.05 mA/cm(2), and a fill factor (FF) of 65.5%, leading to a high power conversion efficiency (PCE) of 5.2%, which is superior to that of the P3HT:PC(61)BM-based device. Most significantly, the amorphous nature of DMPCBA effectively suppresses the thermal-driven aggregation and thus stabilizes the morphology of the P3HT:DMPCBA blend. Consequently, the device retained 80% of its original PCE value against thermal heating at 160 degrees C over 20 h.
Di(4-methylphenyl)methano-C-60 Bis-Adduct for Efficient and Stable Organic Photovoltaics with Enhanced Open-Circuit Voltage
(2011-09-13)
Cheng, Yen-Ju
;
Liao, Ming-Hung
;
Chang, Chih-Yu
;
Kao, Wei-Shun
;
Wu, Cheng-En
A new class of fullerene bis-adducts di(4-methyl-phenyl)methano-C-60 bis-adduct (DMPCBA), di(4-fluorophenyl)methano-C-60 bis-adduct (DFPCBA), and diphenylmethano-C-60 bis-adduct (DPCBA) were rationally designed and easily synthesized. Compared to the lowest unoccupied molecular orbital (LUMO) energy level of PC61BM (-3.95 eV), the double functionalization effectively raises the LUMO energy levels of these fullerene materials to ca. -3.85 eV, regardless of the substituent groups (CH3-, F-, and H-) at the para-position of the phenyl rings. This phenomenon suggests that the plane of the phenyl groups is preferentially parallel to the fullerene surface, leading to poor orbital interactions with C-60 and negligible electronic effect. Importantly, such geometry sterically protects and shields the core C-60 structure from severe intermolecular aggregation, rendering it intrinsically soluble, morphologically amorphous, and thermally stable. The device based on the P3HT:DMPCBA blend exhibited an open-circuit voltage (V-oc) of 0.87 V, a short-circuit current density (J(sc)) of 9.05 mA/cm(2), and a fill factor (FF) of 65.5%, leading to a high power conversion efficiency (PCE) of 5.2%, which is superior to that of the P3HT:PC61BM-based device. Most significantly, the amorphous nature of DMPCBA effectively suppresses the thermal-driven aggregation and thus stabilizes the morphology of the P3HT:DMPCBA blend. Consequently, the device retained 80% of its original PCE value against thermal heating at 160 degrees C over 20 h.
Enhanced Performance and Stability of a Polymer Solar Cell by Incorporation of Vertically Aligned, Cross-Linked Fullerene Nanorods
(2011)
Chang, Chih-Yu
;
Wu, Cheng-En
;
Chen, Shih-Yung
;
Cui, Chaohua
;
Cheng, Yen-Ju
Photoresist 3D profile related etch process simulation and its application to full chip etch compact modeling
(2015-01-01)
Wu, Cheng-En
;
Yang, Wayne
;
Luan, Lan
;
Song, Hua
;
電子工程學系及電子研究所
The optical proximity correction (OPC) model and post-OPC verification that takes the developed photoresist (PR) 3D profile into account is needed in the advanced 2Xnm node. The etch process hotspots caused by poor resist profile may not be fully identified during the lithography inspection but will only be observed after the subsequent etch process. A complete mask correction that targets to final etch CD requires not only a lithography R3D profile model but also a etch process compact model. The drawback of existing etch model is to treat the etch CD bias as a function of visibility and pattern density which do not contain the information of resist profile. One important factor to affect the etch CD is the PR lateral erosion during the etch process due to non-vertical PR side wall angle (SWA) and anisotropy of etch plasma source. A simple example is in transferring patterns from PR layer to thin hard mask (HM) layer, which is frequently used in the double pattern (DPT) process. The PR lateral erosion contributes an extra HM etch CD bias which is deviated from PR CD defined by lithography process. This CD bias is found to have a nontrivial dependency on the PR profile and cannot be described by the pattern density or visibility. In this report, we study the etch CD variation to resist SWA under various etch conditions. Physical effects during etch process such as plasma ion reflection and source anisotropy, which modify the local etch rate, are taken into considerations in simulation. The virtual data are generated by Synopsys TCAD tool Sentaurus Topography 3D using Monte Carlo engine. A simple geometry compact model is applied first to explain the behavior of virtual data, however, it works to some extent but lacks accuracy when plasma ion reflection comes into play. A modified version is proposed, for the first time, by including the effects of plasma ion reflection and source anisotropy. The new compact model fits the nonlinear etch CD bias very well for a wide range of resist SWAs from 65 to 90 degrees, which covers the resist profile diversities in most real situations. This result offers a potential application for both resist profile aware and etch process aware mask correction model in the mask synthesis flow.
Synthesis, Photophysical and Photovoltaic Properties of Conjugated Polymers Containing Fused Donor-Acceptor Dithienopyrrolobenzothiadiazole and Dithienopyrroloquinoxaline Arenes
(2012-03-27)
Cheng, Yen-Ju
;
Ho, Yu-Ju
;
Chen, Chiu-Hsiang
;
Kao, Wei-Shun
;
Wu, Cheng-En
We have developed two nitrogen-bridged pentacyclic donor-acceptor dithienopyrrolobenzothiadiazole (DTPBT) and dithienopyrroloquinoxaline (DTPQX) arenes where the two outer electron-rich thiophene moieties are covalently fastened with the central electron-deficient benzothiadiazole and quinoxaline cores by two nitrogen bridges. These rigid and coplanar DTPBT and DTPQX building blocks were copolymerized with fluorene (F), carbazole (C) and cyclopentadithiophene (CPDT) units via Suzuki or Stifle coupling polymerization to afford six new alternating copolymers PFDTPBT, PCDTPBT, PCPDTDTPBT, PFDTPQX, PCDTPQX and PCPDTDTPQX, respectively. The nitrogen bridges not only planarize the structure to induce stronger intermolecular pi-pi interaction but also play an important role in determining the electronic and photophysical properties of the polymers. The device based on PFDTPQX/PC71BM (1:4, w/w) exhibited a open-circuit voltage (V-oc) of 0.72 V, a short-circuit current (J(sc)) of 8.62 mA/cm(2) and a FF of 0.55 leading to a decent power conversion efficiency (PCE) of 3.40% due to the lower-lying HOMO energy level, and the highest hole-mobility of PFDTPQX
Tuning visible-wavelength spectrum of white-light super-continuum via etalon transmission in lamellar ZnO micro/nanoparticle-stacked structures
(2019-10-01)
Hu, Po-Sheng
;
Chen, Guan-Lin
;
Wu, Cheng-En
;
光電系統研究所
;
影像與生醫光電研究所
Multi-layered micro/nanostructures enable the fine-tuning of spectral bandwidth induced by coherent interference of multi-scattering and refraction bounded by a motive of Fabry Perot etalon. In this paper a ZnO micro/nanostructured thin film device is grown on a 21 nm silver film-sputtered sapphire substrates (0001) and attempted to be complied as a transmission-mode white-light spectrum tuning device. In details, the growth of the structures as a function of temporal duration and the effects of deposition of a 21 nm silver film atop sapphire substrates to the structural and optical properties of ZnO structures are investigated. Results of SEM imaging reveals that the insertion of the silver film enables synthesis of round ZnO particles at micro or nanoscales depending on the duration of growth time as opposed to the floral pattern associated with plain sapphire substrates. Characterizing material crystallization by XRD spectra found one dominant and two minor peaks along the planes of crystallization (002), and (100) and (101), correspondingly. Also, the characteristic PL peak at 380 nm was confirmed when excited at 325 nm, and the intensity decreases as the duration of growth time increases. Finally, growth duration-dependent modulation of peak wavelength and spectral bandwidth of the continuum laser was demonstrated.
Zno Micro/Nanostructures Grown on Sapphire Substrates Using Low-Temperature Vapor-Trapped Thermal Chemical Vapor Deposition: Structural and Optical Properties
(2018-01-01)
Hu, Po-Sheng
;
Wu, Cheng-En
;
Chen, Guan-Lin
;
光電系統研究所
;
影像與生醫光電研究所
In this research, the Zn(C5H7O2)(2)center dot xH(2)O-based growth of ZnO micro/nanostructures in a low temperature, vapor-trapped chemical vapor deposition system was attempted to optimize structural and optical properties for potential biomedical applications. By trapping in-flow gas molecules and Zinc vapor inside a chamber tube by partially obstructing a chamber outlet, a high pressure condition can be achieved, and this experimental setup has the advantages of ease of synthesis, being a low temperature process, and cost effectiveness. Empirically, the growth process proceeded under a chamber condition of an atmospheric pressure of 730 torr, a controlled volume flow rate of input gas, N-2/O-2, of 500/500 Standard Cubic Centimeters per Minute (SCCM), and a designated oven temperature of 500 degrees C. Specifically, the dependence of structural and optical properties of the structures on growth duration and spatially dependent temperature were investigated utilizing scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and ultraviolet-visible transmission spectroscopy. The experimental results indicate that the grown thin film observed with hexagonal structures and higher structural uniformity enables more prominent structural and optical signatures. XRD spectra present the dominant peaks along crystal planes of (002) and (101) as the main direction of crystallization. In addition, while the structures excited with laser wavelength of 325 nm emit a signature radiation around 380 nm, an ultraviolet lamp with a wavelength of 254 nm revealed distinctive photoluminescence peaks at 363.96 nm and 403.52 nm, elucidating different degrees of structural correlation as functions of growth duration and the spatial gradient of temperature. Transmittance spectra of the structures illustrate typical variation in the wavelength range of 200 nm to 400 nm, and its structural correlation is less significant when compared with PL.