Browsing by Author "Yu, Chia-Ming"

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Benzooxadiazole-based donor/acceptor copolymers imparting bulk-heterojunction solar cells with high open-circuit voltages
(2013-01-08)
Jiang, Jian-Ming
;
Yang, Po-An
;
Lan, Shang-Che
;
Yu, Chia-Ming
;
Wei, Kung-Hwa
In this study we used Suzuki cross-coupling to synthesize three new donor/acceptor copolymers-PFTBO, PAF1130, and PCTBO-featuring soluble alkoxy-modified 2,1,3-benzooxadiazole (BO) moieties as acceptor units and electron-rich building blocks-dialkyl fluorene (F), alkylidene fluorene (AF), and carbazole (C), respectively-as donor units. These polymers, which we characterized using gel permeation chromatography, thermogravimetric analysis, NMR spectroscopy, UV-Vis absorption spectroscopy, and electrochemical cyclic voltammetry, exhibited good solubility, low-lying energy levels for their highest occupied molecular orbitals, excellent thermal stability, and air stability. Using these polymers, we fabricated bulk-heterojunction solar cell devices having the structure indium tin oxide/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate/polymer:[6,6]-phenyl-C-61-butyric acid methyl ester (PC61BM) (1:1, w/w)/Ca/Al. Under AM 1.5G illumination (100 mW cm(-2)), the solar cell incorporating PFTBO exhibited a high value of V-OC of 1.04 V and that based on PCTBO provided a power conversion efficiency of 4.1% without the need for any post treatment. (C) 2012 Elsevier Ltd. All rights reserved.
Conjugated random copolymers of benzodithiophene-benzooxadiazole-diketopyrrolopyrrole with full visible light absorption for bulk heterojunction solar cells
(2013)
Jiang, Jian-Ming
;
Chen, Hsiu-Cheng
;
Lin, His-Kuei
;
Yu, Chia-Ming
;
Lan, Shang-Che
We have used Stille coupling polymerization to synthesize a series of new donor-acceptor (D-A) conjugated random copolymers-PBDTT-BO-DPP-that comprise electron-rich alkylthienyl-substituted benzodithiophene (BDTT) units in conjugation with electron-deficient 2,1,3-benzooxadiazole (BO) and diketopyrrolopyrrole (DPP) moieties that have complementary light absorption behavior. These polymers exhibited excellent thermal stability with thermal degrading temperatures higher than 340 degrees C. Each of these copolymers exhibited (i) broad visible light absorption from 400 to 900 nm and (ii) a low optical band gap that is smaller than 1.4 eV and a low-lying highest occupied molecular orbital that is deeper than -5.22 eV. As a result, bulk heterojunction photovoltaic devices derived from these polymers and fullerenes provided a high short-circuit current density that is larger than 12 mA cm(-2). In particular, a photovoltaic device prepared from the PBDTT-BO-DPP (molar ratio, 1 : 0.5 : 0.5)/PC71BM (w/w, 1 : 2) blend system with 1-chloronaphthalene (1 volume%) as an additive exhibited excellent photovoltaic performance, with a value of V-oc of 0.73 V, a high short-circuit current density of 17 mA cm(-2), a fill factor of 0.55, and a promising power conversion efficiency of 6.8%, indicating that complementary light-absorption random polymer structures have great potential for increasing the photocurrent in bulk heterojunction photovoltaic devices.
KPAT: A Kernel and Protocol Analysis Tool for Embedded Networking Devices
(2014-01-01)
Wang, Ming-Hung
;
Yu, Chia-Ming
;
Lin, Chia-Liang
;
Tseng, Chien-Chao
;
Yen, Li-Hsing
Sniffer tools capture protocol data. Kernel-profiling tools track function calls and events occurring in the kernel. These two types of tools help us observe external and internal behaviors of networking protocols, respectively. We need both types of data for a comprehensive view of protocol behavior. However, none of existing tools performs these two tasks in an integrated way. We developed Kernel and Protocol Analysis Tool (KPAT). KPAT injects software probes into Linux kernel to track interested function calls and event occurrences in the kernel. Probe injection is done systematically and does not require recompiling the kernel. A module in KPAT finds the association between the tracked functions and protocol data captured by an independent sniffer. The result as an integrated log allows users to identify two-way relationship between protocol data and the execution sequence of network functions in the kernel. We successfully used KPAT to identity accurate latency of each handover phase in IEEE 802.11 wireless networks. Experimental results show that KPAT causes light overhead to the patched kernel.
Photonic crystal circular-shaped microcavity and its uniform cavity-waveguide coupling property due to presence of whispering gallery mode
(2007-07-23)
Lee, Po-Tsung
;
Lu, Tsan-Wen
;
Yu, Chia-Ming
;
Tseng, Chung-Chuan
;
光電工程學系
In this report, we investigate a photonic crystal circular- shaped microcavity ( removing seven air holes) sustaining whispering- gallery mode ( WGM) by shifting the 12 nearest air holes according to the concept of cavity- shaping in micro- disk and micro- gear lasers. The WGM modal characteristics are investigated by three- dimensional ( 3D) finite- difference time- domain ( FDTD) simulations. From well- fabricated devices and simulated results, we obtain and identify WGM single- mode lasing with low threshold and high measured quality factor. By inserting additional waveguides, we also investigate its uniform coupling behaviors in different waveguide- cavity- waveguide geometries in both FDTD simulations and experiments. (c) 2007 Optical Society of America.
The new low-band gap polymers comprising C-, Si-, or N-bridged dithiophene and alkoxy-modified 2,1,3-benzooxadiazole units for bulk heterojunction solar cells
(2012-10-01)
Jiang, Jian-Ming
;
Yang, Po-An
;
Yu, Chia-Ming
;
Lin, His-Kuei
;
Huang, Kuei-Chun
In this study, we used Stille coupling polymerization to synthesize a series of new low-band gap-conjugated polymersPCyTBO, PCySiTBO, and PCyNTBOcomprising mainly electron-rich C-, Si-, and N-bridged dithiophene units in conjugation with electron-deficient alkoxy-modified 2,1,3-benzooxadiazole moieties. The highest occupied molecular orbital energy levels of these polymers become higher as the electron-donating ability of C-, Si-, or N-bridged dithiophene units increases. These polymers also displayed excellent thermal stability and broad spectral absorptions, with PCySiTBO revealing some crystallinity. As a result, the photovoltaic device incorporating the PCySiTBO/PC71BM (1:1) blend system and 1,8-diiodooctane (2 vol %) as an additive exhibited excellent performance, under AM 1.5 G irradiation (100 mW cm-2), with a value of Voc of 0.64 V, a short-circuit current density of 13.8 mA cm-2, a fill factor of 0.57, and a promising power conversion efficiency of 5.0%. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012