Browsing by Author "Chu, Chih-Wei"

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1-(3-Methoxycarbonyl)propyl-2-selenyl-[6,6]-methanofullerene as a n-Type Material for Organic Solar Cells
(2011-07-01)
Chuang, Shih-Ching
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Chiu, Chih-Wei
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Chien, Shang-Chieh
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Chu, Chih-Wei
;
Chen, Fang-Chung
Demand for green and renewable energy is stimulating research into future materials for energy production. Thin films of materials possessing both electron accepting and donating functions play a unique role in solar energy technology because of their lightweight, flexibility, and economical, low-temperature, and large-area fabrication. A [60]fullerene derivative,[6,6]-2-selenyl-C(61)-butyric acid methyl ester (SeCBM), has been synthesized in three steps, namely through Friedel-Crafts acylation of selenophene, hydrazone formation and Bamford-Steven reaction. Organic photovoltaic device incorporating SeCBM and the conducting polymer P3HT exhibited an average power conversion efficiency of 3.26% and a champion efficiency as high as 3.81% under AM 1.5G irradiation. (C) 2011 Elsevier B.V. All rights reserved.
2-Alkyl-5-thienyl-Substituted Benzo[1,2-b:4,5-b ']dithiophene-Based Donor Molecules for Solution-Processed Organic Solar Cells
(2013-10-09)
Patra, Dhananjaya
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Huang, Tzu-Yen
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Chiang, Chao-Cheng
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Maturana, Ramon Orlando Valencia
;
Pao, Chun-Wei
In this study, we have strategically designed and convergently synthesized two novel, symmetrical, and linear A-D-A-type pi-conjugated donor molecules (TBDTCNR, TBDTCN), each containing a planar electron-rich 2-octylthiene-5-yl-substituted benzodithiophene (TBDT) unit as the core, flanked by octylthiophene units and end-capped with electron-deficient cyanoacetate (CNR) or dicyanovinyl (CN) units. We thoroughly characterized both of these materials and investigated the effects of the end groups (CNR, CN) on their optical, electrochemical, morphological, and photovoltaic properties. We then fabricated solution-processed bulk heterojunction organic solar cells incorporating TBDTCNR and TBDTCN. Among our tested devices, the one containing TBDTCNR and [6,6]-phenyl-C-61-butyric acid methyl ester in a 1:0.40 ratio (w/w) exhibited the highest power conversion efficiency (5.42%) with a short-circuit current density (J(sc)) of 9.08 mA cm(-2), an open circuit voltage (V-oc) of 0.90 V, and an impressive fill factor (FF) of 0.66 under AM 1.5G irradiation (100 mW cm(-2)). The FFs of these solution-processed small-molecule organic solar cells (SMOSCs) are outstanding when compared with those recently reported for benzodithiophene (BDT)-based SMOSCs, because of the high crystallinity and excellent stacking properties of the TBDT-based compounds.
A cascade energy band structure enhances the carrier energy in organic vertical-type triodes
(2013-09-01)
Cheng, Shiau-Shin
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Ramesh, Mohan
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Chen, Guan-Yuan
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Fung, Chun-Lin
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Chen, Li-Ming
Organic vertical-type triodes (OVTs) based on the cascade energy band structure as emitter layer are studied. The electric characteristics were dramatically enhanced while incorporating the cascade energy under current driving and voltage driving modes. The improvement is attributed to that injection carriers can obtain higher energy through a stepwise energy level. When the device has a layered structure of F16CuPC (10 nm)/PTCDI (10 nm)/pentacene (100 nm) in emitter, it exhibits a common-base transport factor of 0.99 and a common-emitter current gain of 225 under current driving mode and exhibits a high current modulation-exceeding -520 mu A for a low collector voltage of -5 V and a base voltage of -5 V and the current on/off ratio of 10(3) under voltage driving mode. Furthermore, we realized first organic current mirror that exhibited out/in current ratio of 0.75 and output resistance of 10(5) Omega by using the OVTs. (C) 2013 Published by Elsevier B.V.
A counter electrode based on hollow spherical particles of polyaniline for a dye-sensitized solar cell
(2012)
Huang, Kuan-Chieh
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Hu, Chih-Wei
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Tseng, Chen-Ya
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Liu, Chen-Yu
;
Yeh, Min-Hsin
Hollow spherical polyaniline (hsPANI) particles are synthesized and deposited on an ITO/glass substrate to prepare a counter electrode (designated as hsPANI-CE) for a dye-sensitized solar cell (DSSC). The structure and crystallization of the hsPANI particles are characterized by using high resolution transmission electron microscopy (HR-TEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectra. A power-conversion efficiency (h) of 6.84% is obtained for the DSSC with the hsPANI-CE, while it is 6.02% in the case of the DSSC with a CE based on pristine PANI (designated as PANI-CE). Such enhancement is attributed to the hsPANI film having a larger active surface area (A) of 0.191 cm(2), compared to that of the PANI film (A = 0.126 cm(2)), both values being estimated by a rotating disk electrode (RDE). Cyclic voltammetric (CV) curves have evidenced that the electro-catalytic ability of the hsPANI-CE for the reduction of tri-iodide (I-3(-)) ions is higher than that of the PANI-CE. As a reference, the DSSC with a Pt-sputtered CE gives an h of 7.17%. Electrochemical impedance spectroscopic (EIS) spectra are used to substantiate the photovoltaic behaviors. The results suggest that the film consisting of hsPANI particles can be a potential catalytic layer for the replacement of Pt in the CE of a DSSC.
A dual-functional additive improves the performance of molecular bulk heterojunction photovoltaic cells
(2014)
Farahat, Mahmoud E.
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Wei, Hung-Yu
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Ibrahem, Mohammed Aziz
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Boopathi, Karunakara Moorthy
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Wei, Kung-Hwa
In this paper we report a simple and effective approach towards improving the performance of molecular bulk heterojunction (BHJ) photovoltaics through incorporation of a new, nonvolatile processing additive; (3-chloropropyl) trimethoxysilane (CP3MS). A small amount of the additive CP3MS combined with post-annealing treatment significantly enhanced the power conversion efficiency (PCE) of dialkylated diketopyrrolopyrrole chromophore (SMDPPEH)-based molecular BHJ solar cells. The PCE increased from 2.75% for a device prepared without the additive or annealing to 4.55% for a device containing 0.1% CP3MS that had been subjected to post-annealing treatment at 100 degrees C for 10 min. CP3MS performed an interesting dual function when incorporated as an additive in molecular BHJ devices. The first was that it controlled the morphology: the addition of 0.1% CP3MS to the SMDPPEH: PC61BM blend was sufficient to improve the film's crystallinity and morphology. The second function was the spontaneous migration of the CP3MS molecules from the bulk to the interface between the active layer and the Al cathode, forming an ultrathin interlayer that acted as a buffer layer suppressing charge recombination and enhancing charge transport at the interface. Analyses using atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, together with examinations of device performance, confirmed the dual-functional nature of CP3MS as an additive. CP3MS also showed its promising ability to enhance the performance of different blend systems. The performance of benzodithiophene (BDT)-based molecular solar cells enhanced from 3.05% without additive to 3.8% with the incorporation of 0.1% CP3MS.
A high performance electrochemical sensor for acetaminophen based on a rGO-PEDOT nanotube composite modified electrode
(2014)
Huang, Tzu-Yen
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Kung, Chung-Wei
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Wei, Hung-Yu
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Boopathi, Karunakara Moorthy
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Chu, Chih-Wei
In this study, we perform an electrochemical sensing using a conductive composite film containing reduced graphene oxide (rGO) and poly(3,4-ethylenedioxythiophene) nanotubes (PEDOT NTs) as an electrode modifier on a glassy carbon electrode (GCE). Scanning electron microscopy suggests that the rGO covers the surface of GCE uniformly and the PEDOT NTs act as a conducting bridge to connect the isolated rGO sheets. By combining these two materials, the conductivity and the surface coverage of the film can be enhanced, which is beneficial for electrochemical sensing. The rGO-PEDOT NT composite modified electrode is applied for an effective sensor to analyze acetaminophen. The obtained electrochemical activity is much higher than those obtained by the rGO-and PEDOT NT-modified electrodes; the higher electrochemical activity may be attributed to the higher conductivity and greater coverage of the rGO-PEDOT NT composite film on the GCE. Furthermore, interference tests indicate that the rGO-PEDOT NT composite modified electrode exhibits high selectivity toward the analyte. This novel method for combining the rGO and PEDOT NTs establishes a new class of carbon material-based electrodes for electrochemical sensors.
A new supramolecular film formed from a silsesquioxane derivative for application in proton exchange membranes
(2012-01-14)
Cheng, Chih-Chia
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Yen, Ying-Chieh
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Ko, Fu-Hsiang
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Chu, Chih-Wei
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Fan, Shih-Kang
A new polyhedral oligomeric silsesquioxane ionomer (HO-doped PUSS-C11-Py) has been investigated. This new ionomer is able to self-assemble through macromers by quadruple hydrogen bonding interactions into a physically crosslinked polymer-like material that can be easily fabricated into films with micro-phase separation. This HCl-doped POSS-C11-Py membrane exhibits higher proton conductivity than a typical Nafion membrane at high temperature, which is extremely rare for a non-sulfonic acid system. This newly developed material may provide an alternative route toward design and fabrication of a new type of proton exchange membranes.
A novel ball milling technique for room temperature processing of TiO2 nanoparticles employed as the electron transport layer in perovskite solar cells and modules
(2018-04-28)
Singh, Mriganka
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Chiang, Chien-Hung
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Boopathi, Karunakara Moorthy
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Hanmandlu, Chintam
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Li, Gang
Anatase titanium dioxide (an-TiO2) is often used as the electron transporting material (ETM) in planar-heterojunction perovskite solar cells (PSCs) because of its excellent semiconductor characteristics, outstanding optical transmittance, and suitable band structure. Herein, we report an inexpensive method for mass-scale production of TiO2 ETMs at room temperature (RT similar to 30 degrees C), involving the grinding of large clumps of an-TiO2 to form a suspension of TiO2 nanoparticles (NPs) in isopropyl alcohol for meso-superstructured PSCs. This process does not involve any chemical synthesis; it is a purely physical process. The lowest unoccupied molecular orbital (LUMO) of ground an-TiO2 NPs, estimated using ultraviolet photoelectron spectroscopy (UPS), was ca. 4.06 eV, which is a salient feature for the active layer. A regular perovskite solar cell (PSC) based on a CH3NH3PbI3 absorber and ground an-TiO2 ETL exhibited a champion power conversion efficiency (PCE) of 17.43% with an active area of 0.1 cm(2). The same ground an-TiO2 NPs were used to fabricate a large-area (designated area: 25.2 cm(2)) PSC and a PCE of 14.19% was achieved. PSC devices incorporating the ground an-TiO2 NP ETLs exhibited an attractive long-term device stability, with the PCE retaining approximately 85% of the initial values after 80 days.
A Strategic Buffer Layer of Polythiophene Enhances the Efficiency of Bulk Heterojunction Solar Cells
(2010-05-01)
Wei, Hung-Yu
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Huang, Jen-Hsien
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Ho, Kuo-Chuan
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Chu, Chih-Wei
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光電工程學系
We have developed polymer solar cells featuring a buffer layer of polythiophene (PT) sandwiched between the active layer and the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer. We attribute the improvement in power conversion efficiency of these polymer solar cells, relative to that of those based on poly(3-hexylthiophene):[6,6]-phenyl-C(61)-butyric acid methyl ester (P3HT:PCBM), to a reduction in the degree of carrier recombination at the junction interface. Because the conductivity and the energy level of PT can be tuned simply by applying a bias to it in an electrolytic solution, we also investigated the effect of the energy level on the devices' performances. The power conversion efficiency of a solar cell containing a PT buffer layer reached 4.18% under AM 1.5 G irradiation (100 mW/cm(2)).
A ternary cascade structure enhances the efficiency of polymer solar cells
(2010)
Huang, Jen-Hsien
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Velusamy, Marappan
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Ho, Kuo-Chuan
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Lin, Jiann-Tsuen
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Chu, Chih-Wei
In this study, a novel solution-processed small molecule (TQTFA) for use as an electron donor has been incorporated into organic solar cells based on poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C71-butyric acid methyl (PC[70]BM). The combination of TQTFA with P3HT and PC[70]BM allows not only a broad absorption but also tuning of the inter energy level leading to a higher short-circuit current (J(SC)) and open-circuit voltage (V(OC)). The best performing devices exhibited a power conversion efficiency of 4.50%. The efficiency is increased by almost 15% when compared to the one without TQTFA.
Achieving efficient poly(3,4-ethylenedioxythiophene)-based supercapacitors by controlling the polymerization kinetics
(2011-08-01)
Huang, Jen-Hsien
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Chu, Chih-Wei
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光電工程學系
;
Department of Photonics
In this study, we have prepared a series of poly(3,4-ethylenedioxythiophene) (PEDOT) with various molecular weight by using an inhibitor, imidazole (Im). The X-ray diffraction (XRD) results show that the PEDOT with larger molecular weight enhances the polymer chain ordering and stacking which leads to higher conductivity. With increasing the amount of Im, the conductivity of PEDOT can be increased from 4.01 S cm(-1) (Im = 0.0 M) to 153.6S cm(-1) (Im = 1.8 M). Comparisons of the cyclic voltammetry (CV), it enables correlation between the conductivity and specific capacitance, which is important for understanding the electrochemical capacitive behavior of conjugated polymer for pseudo-capacitor application. The PEDOT prepared with 1.8M Im shows a specific capacitance of 124 F g(-1), which is 2.2 times larger than the one without Im (57 F g(-1)). (C) 2011 Elsevier Ltd. All rights reserved.
Ambipolar transport behavior in In(2)O(3)/pentacene hybrid heterostructure and their complementary circuits
(2008-07-21)
Dhananjay
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Ou, Chun-Wei
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Yang, Chuan-Yi
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Wu, Meng-Chyi
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Chu, Chih-Wei
In this Letter, ambipolar transport properties of a bilayer of In(2)O(3) and a pentacene heterostructure have been realized. While In(2)O(3) thin film transistors exhibited a n-channel behavior, pentacene presumed p-channel characteristics on bare SiO(2)/p-Si substrates. However, when a bilayer of In(2)O(3)/pentacene was realized on the gate dielectrics, the hybrid structure exhibited both n- and p-channel conductions, depicting an ambipolar transistor behavior. When two identical ambipolar transistors were integrated to establish an inverter structure, a voltage gain of 10 was obtained. The results indicate that these heterostructures can be utilized for the complementary circuits. (C) 2008 American Institute of Physics.
Annealing effect of polymer bulk heterojunction solar cells based on polyfluorene and fullerene blend
(2009-02-01)
Huang, Jen-Hsien
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Yang, Chuan-Yi
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Ho, Zhong-Yo
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Kekuda, Dhananjay
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Wu, Meng-Chyi
Control of blend morphology at the nanoscale and high charge mobility is essential for polymer photovoltaic devices in terms of their power conversion efficiencies (PCE). In the case of bulk heterojunctions solar cells, both blend morphology and charge mobility are influenced by thermal treatment. In this manuscript, we study the effects of annealing temperature on polymer PV devices with blends of poly[9,9'-dioctyl-fluorene-co-bithiophene] (F8T2) and [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM). The morphological changes of blended films were observed upon thermal annealing temperature near and above glass transition temperature (130 degrees C). Such microstructural transformations resulted in modified charge transport pathways and therefore greately influenced the device performance. The highest PCE of 2.14% with an open-circuit voltage (V(OC)) of 0.99 V and a short-circuit current (J(SC)) of 4.24 mA/cm(2) was achieved by device annealing at 70 degrees C for 20 min. (C) 2008 Elsevier B.V. All rights reserved.
Anomalous p-channel amorphous oxide transistors based on tin oxide and their complementary circuits
(2008-03-24)
Ou, Chun-Wei
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Ho, Zhong Yo
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Chuang, You-Che
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Cheng, Shiau-Shin
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Wu, Meng-Chyi
In this article, we report the fabrication of SnO(2) thin film transistors (TFTs) fabricated by reactive evaporation. Different from the previous reports, the fabricated TFTs exhibit p-type conductivity in its undoped form. The postdeposition annealing temperature was tuned to achieve p-channel SnO(2) TFTs. The on/ off ratio and the field-effect mobility were similar to 10(3) and 0.011 cm(2)/V s, respectively. To demonstrate inverter circuit, two devices with different threshold voltages were combined and an output gain of 2.8 was achieved. The realization of p-channel oxide TFTs would open up new challenges in the area of transparent electronics. (C) 2008 American Institute of Physics.
Applications of novel dithienothiophene- and 2,7-carbazole-based conjugated polymers with surface-modified ZnO nanoparticles for organic photovoltaic cells
(2011-05-31)
Fang, Hsiao-Ping
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Chiang, I-Hung
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Chu, Chih-Wei
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Yang, Chang-Chung
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Lin, Hong-Cheu
Two kinds of novel conjugated polymers containing 2,7-carbazole, thiophene, and fused-dithienothiophene rings as backbones bearing acid-protected and benzoic acid pendants (PC1 and PC2, respectively) were utilized for organic solar cell applications. The absorption spectra of these polymers (in both solutions and solid films) showed an absorption range at 300-580 nm. Furthermore, ZnO nanoparticles were synthesized and surface-modified with pyridyl surfactants (ZnOpy) to be ca. 3-4 nm. The pyridyl surfactants of ZnOpy nanoparticles (as electron acceptors to partially replace expensive electron acceptor PCBM) not only induce supramolecular interactions with benzoic acid pendants of polymer PC2 via H-bonds, but also enhance the homogeneous dispersions of ZnOpy nanoparticles in polymer PC2. Thus, the ternary systems of PC1-N2/ZnOpy/PCBM in weight ratios of 1:0.05:1 and 1:0.1:1 were investigated in bulk heterojunction polymer solar cells (PSCs). Under the standard illumination of AM 1.5, 100 mW/cm(2), the best power conversion efficiency (PCE) of the PSC cell containing a polymer blend of PC2/ZnOpy/PCBM = 1:0.05:1 reached PCE = 0.55%, with J(sc) = 2.11 mA/cm(2), V(oc) = 0.88 V, and FF = 29.4%. (C) 2011 Elsevier B.V. All rights reserved.
Asymmetric Benzotrithiophene-Based Hole Transporting Materials Provide High-Efficiency Perovskite Solar Cells
(2020-07-01)
Budiawan, Widhya
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Lai, Kuan-Wen
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Karuppuswamy, Priyadharsini
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Jadhav, Tushar Sanjay
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Lu, Yen-An
In this study, we synthesized a series of small-molecule benzotrithiophenes (BTTs) and used them as hole transporting materials (HTMs) in perovskite solar cells (PSCs). The asymmetric benzo[2,1-b:-3,4-b':5,6-b"]trithiophene unit was used as the central core to which were appended various donor groups, namely, carbazole (BTT-CB), thieno thiophene (BTT-FT), triphenylamine (BTT-TPA), and bithiophene (BTT-TT). The extended aromatic core in the asymmetric BTT provided full planarity, thereby favoring intermolecular pi-stacking and charge transport. The physical, optical, and electrical properties of these small-molecule HTMs are reported herein. BTT-TT displayed good crystallinity and superior hole mobility, when compared with those of the other three HTMs, and formed smooth and uniform surfaces when covering the perovskite active layer. Accordingly, among the devices prepared in this study, a PSC incorporating BTT-TT as the HTM achieved the highest power conversion efficiency (18.58%). Moreover, this BTT-TT-containing device exhibited good stability after storage for more than 700 h. Thus, asymmetric BTTs are promising candidate materials for use as small-molecule HTMs in PSCs.
Balanced carrier transport in organic solar cells employing embedded indium-tin-oxide nanoelectrodes
(2011-02-14)
Hsu, Min-Hsiang
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Yu, Peichen
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Huang, Jen-Hsien
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Chang, Chia-Hua
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Wu, Chien-Wei
In this paper, we present evidence of balanced electron and hole transport in polymer-fullerene based solar cells by means of embedded indium-tin-oxide nanoelectrodes. Enabled by a controllable electrochemical deposition, the individual nanoelectrodes are uniformly enclosed by a poly (3,4-ethylenedioxythiophene) hole-conducting layer, allowing a relatively short route for holes to reach the anode and hence increasing the effective hole mobility. Consequently, the power conversion efficiency and photogenerated current are maximized with a deposition condition of 50 mu C, where the ratio of the electron to hole mobility is nearly unity. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556565]
Balanced carrier transport in organic solar cells employing embedded indium-tin-oxide nanoelectrodes (vol 98, 073308, 2011)
(2011-03-14)
Hsu, Min-Hsiang
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Yu, Peichen
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Huang, Jen-Hsien
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Chang, Chia-Hua
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Wu, Chien-Wei
Balancing the ambipolar conduction for pentacene thin film transistors through bifunctional electrodes
(2008-06-23)
Yang, Chuan-Yi
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Dhananjay
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Cheng, Shiau-Shin
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Ou, Chun-Wei
;
Chuang, You-Che
We report an effective way to equilibrate hole and electron transport in ambipolar pentacene thin film transistors (TFTs). It was achieved by inserting an ultra thin lithium fluoride (LiF) layer at the electrode/organic interface to form a bifunctional source/drain electrode. It can be observed that the presence of ultrathin LiF layer will facilitate the injection of electrons from source/drain electrodes to organic semiconductor, resulting in a significant enhancement of the n-channel conduction, without sacrificing p-channel conduction for ambipolar pentacene TFTs. These factors make them potential candidates for the organic complementary circuits and inverter circuits of these ambipolar TFTs are also demonstrated. (c) 2008 American Institute of Physics.
Bioinspired assembly of functional block-copolymer nanotemplates
(2013)
Lin, I. -Hong
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Cheng, Chih-Chia
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Chuang, Wei-Tsung
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Chen, Jem-Kun
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Jeng, U. -Ser
A new concept on bioinspired assembly of functional diblock copolymers, capable of forming different microstructures through nucleobase-induced supramolecular interactions, has been explored. In this paper, a new series of uracil-functionalized poly(epsilon-caprolactone)-b-(4-vinylbenzyl uracil)s (PCL-b-PVBU) have been prepared which exhibit a high self-complementary ability in solution and solid states owing to the formation of uracil-uracil pairs by induced hierarchical self-assembly. The ordered morphologies of PCL-b-PVBU diblock copolymers changed from a lamellar, hexagonally packed cylinder to a sphere with respect to the content of the hydrogen bond segment. Moreover, we further show that the PCL segment could be easily extracted by enzymatic degradation, leading to a cylinder porous structure of long-range order, which gives a facile method for the fabrication of uracil-functionalized nanotemplates. In addition, bio-complementary PCL-b-PVBU/9-hexadecyladenine (AC16) hierarchical supramolecular complexes formed through strong cooperative hydrogen bonding between the uracil group of PVBU and the adenine group of A-C16. When the mixing ratios of PCL-b-PVBU/AC16 differ from the stoichiometric ratio, these complexes self-assemble into well-ordered lamellar and hexagonal structures; the changing morphology at different AC16 loadings reveals that the molecular structures of the PCL-b-PVBU/AC16 complexes are readily tailored.