Browsing by Author "Lai, Yu-Ying"

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A new ladder-type benzodi(cyclopentadithiophene)-based donor-acceptor polymer and a modified hole-collecting PEDOT: PSS layer to achieve tandem solar cells with an open-circuit voltage of 1.62 V
(2013)
Chen, Yung-Lung
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Kao, Wei-Shun
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Tsai, Che-En
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Lai, Yu-Ying
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Cheng, Yen-Ju
We have developed a new ladder-type conjugated polymer PBDCPDT-FBT and a robust interconnecting layer (ICL) integrating a hole-collecting m-PEDOT:PSS layer with an electron-collecting ZnO layer. The inverted device using PBDCPDT-FBT exhibited a high power conversion efficiency (PCE) of 5.76% with a V-oc of 0.81 V, a J(sc) of 12.82 mA cm(-2), and a FF of 55.5%. The inverted tandem device incorporating the PBDCPDT-FBT and ICL achieves a V-oc of 1.62 V leading to a PCE of 7.08%.
A New Ladder-Type Germanium-Bridged Dithienocarbazole Arene and Its Donor-Acceptor Conjugated Copolymers: Synthesis, Molecular Properties, and photovoltaic Applications
(2014-11-11)
Jwo, Pei-Chi
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Lai, Yu-Ying
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Tsai, Che-En
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Lai, Yun-Yu
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Liang, Wei-Wei
We have developed a new germanium-bridged heptacyclic arene, dithienogermolocarbazole (DTGC), in which two outer thiophene subunits are covalently fastened to the central 2,7-carbazole core by two dibutylgermanium bridges. The germole moieties embedded in the DTGC structure were successfully constructed by one-pot nucleophilic cyclization in a high yield of 88%. Because of the relatively lower polarity of carbongermanium bonds, the DTGC unit is chemically stable under basic conditions, rendering its more versatile functionalization. Comparison of germanium-bridged DTGC with the carbon-bridged DTCC (dithienocyclopentacarbazole) and silicon-bridged DTSC (dithienosilolocarbazole) analogues reveals that the HOMO energy level of DTGC lies between those of DTCC and DTSC and so does the LUMO energy level of DTGC. Density functional theory (DFT) calculations suggest that DTSC and DTGC have more bent structures than DTCC, which plays an important role in determining their frontier orbital energies. The structural disparity could be amplified in their corresponding polymers. The DTGC unit was copolymerized with four different comonomers, including benzothiadiazole (BT), dithienylbenzothiadiazole (DTBT), difluorobenzothiadiazole (FBT), and dithienyldifluorobenzothiadiazole (DTFBT) to yield a series of new alternating donoracceptor copolymers, poly(dithienogermolo-carbazole-alt-benzothiadiazole) (PDTGCBT), poly(dithienogermolocarbazole-alt-dithienylbenzothiadiazole) (PDTGCDTBT), poly(dithienogermolocarbazole-alt-difluorobenzothiadiazole) (PDTGCFBT), and poly(dithienogermolocarbazole-alt-dithienyldifluorobenzothiadiazole) (PDTGCDTFBT). Because of the two additional thiophene rings in the repeating units on the backbone to facilitate pi-electron delocalization, PDTGCFDTBT showed a lower optical band gap than PDTGCFBT. Furthermore, PDTGCDTFBT also showed the lower-lying LUMO and HOMO energy levels than PDTGCDTBT as a result of the electron-withdrawing fluorine atoms. Consequently, the bulk heterojunction solar cell incorporating PDTGCDTFBT delivered the highest performance with V-oc of 0.84 V, Jsc of 9.87 mA/cm(2), FF of 48.8%, and PCE of 4.05%. By adding 3 vol % 1-chloronaphthalene to tailor the morphology, the solar cell using PDTGCDTFBT with higher molecular weight exhibited the improved efficiency of 4.50% with a V-oc of 0.84 V, a J(sc) of 11.19 mA/cm(2), and an FF of 47.7%.
A New Pentacyclic Indacenodiselenophene Arene and Its Donor-Acceptor Copolymers for Solution-Processable Polymer Solar Cells and Transistors: Synthesis, Characterization, and Investigation of Alkyl/Alkoxy Side-Chain Effect
(2013-10-08)
Chang, Huan-Hsuan
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Tsai, Che-En
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Lai, Yu-Ying
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Liang, Wei-Wei
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Hsu, So-Lin
A pentacyclic indacenodiselenophene (IDS) arene was synthesized via intramolecular Friedel-Craft cyclization of the selenophene moieties. This IDS framework was used as a model system to investigate the alkyl/alkoxy side-chain effect by preparing IDS-OCH8 and IDS-C-6, where the side chains on the sp(3) carbon in the cyclopentadienyl ring are 4-octyloxyphenyl groups and 4-hexylphenyl groups, respectively. The SnIDS-OCH8 and Sn-IDS-C-6 monomers were copolymerized with 4,7dibromo-2,1,3-benzothiadiazole (BT), 4,7-diiodo-5,6-difluoro-2,1,3-benzothiadiazole (FBT) and 1,3-dibromothieno[3,4-dpyrrole-4,6-dione (TPD) acceptor monomers by Stil le polycondensation to afford five new IDS-based donor acceptor alternating copolymers, PIDSBT-OCH8, PIDSBTC6) PIDSFBT-OCH8, PIDSFBT-C-6, and PIDSTPD-C-6. Despite the fact that the octyloxy and hexyl side chains play a negligible role in the optical and electrochemical properties of the resulting polymers, the solar cell performance is highly associated with the side chains of the polymers. Under similar device fabrication conditions, the PIDSBT-C-6 and PIDSFBT-C-6-based devices showed much improved efficiencies than the corresponding PIDSBT-OCH8, and PIDSFBT-OCH8-based devices (2.6% and 1.9% vs 3.8% and 3.9%). The improvement is mainly the result of much enhanced J(sc) values. Consistently, PIDSBT-C-6 and PIDSFBT-C-6 exhibited much higher FET hole mobilites than the corresponding PIDSBT-OCH8, and PIDSFBT-OCH8. These results clearly revealed that the 4-hexylphenyl group is a more suitable side chain than the 4-octyloxyphenyl group in the IDS system, and the side-chain dependent mobility of the polymers is the dominating factor to determine the photocurrents and efficiencies of PSCs. PIDSBT-C-6 exhibited a high hole mobility of 0.08 cm(2) V-1 s(-1) and PIDSTPD-C-6:PC71BM (1:4 in wt %)-based solar cell with 5 v% chloronaphthalene (CN) delivered a V-oc of 0.92 V, a J(sc) of 9.77 mA/cm(2), an FF of 51%, and a highest PCE of 4.6%. This work not only discloses a new selenophene-containing ladder-type IDS structure and its copolymers but also provides useful insights into the allcyl/alkoxy side-chain effect for future design of conjugated polymers.
A New sp2-sp2 Dialkylethylene-Bridged Heptacyclic Ladder-Type Arene for High Efficiency Polymer Solar Cells
(2013-04-01)
Wu, Jhong-Sian
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Lai, Yu-Ying
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Cheng, Yen-Ju
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Chang, Chih-Yu
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Wang, Chien-Lung
A new dithienobenzo-carbazole (DTBC) heptacyclic arene using sp2-sp2 dialkylethylene moiety as the bridge was successfully synthesized by Suzuki-Miyaura cross-coupling reaction. This facile benzoannulation planarizes the conjugated framework with the concomitant introduction of four octyl substituents, making the newly designed copolymer PDTBCDTBT exhibit solution processability, superior absorption ability, lower-lying HOMO energy level, and crystalline nature. The solar cell using PDTBCDTBT has produced a high efficiency of 6.2%, which outperforms the corresponding sp3-hybridized C-bridged, Si-bridged and N-bridged analogous polymers.
Angular-Shaped 4,10-Dialkylanthradiselenophene and Its Donor-Acceptor Conjugated Polymers: Synthesis, Physical, Transistor, and Photovoltaic Properties
(2015-10-13)
Lai, Yu-Ying
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Chang, Huan-Hsuan
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Lai, Yun-Yu
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Liang, Wei-Wei
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Tsai, Che-En
An angular-shaped and isomerically pure 4,10-di(2-octyl)dodecylanthradiselenophene (aADS) was successfully developed. The expedient synthesis to form the framework of aADS with two lateral side chains regioseleclively at its 4,10-positions is via a base-induced propargyl-allenyl isomerization/6 pi-electrocyclization/aromatization protocol. This pentacyclic distannylated aADS unit was then copolymerized with dithienyldiketopyrrolopyrrole (DPP) and dithienyl-5,6-difluoro-2,1,3-benzothiadiazole (DTFBT) acceptors with different alkyl side chains to afford four donor-acceptor copolymers: PaADSDPP, PaADSDTFBT-C-4, PaADSDTFBT-C-8, and PaADSDTFBT-C8C12. UV-vis spectroscopy and cyclic voltammetry revealed that PaADSDPP has the narrowest energy band gap, and PaADSDTFBT-C8C12 has larger band gap than PaADSDTFBT-C-4 and PaADSDTFBT-C-8. Two layer ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) calculations were implemented to investigate the disparity in optical, electrochemical, and device properties between these polymers. Both experimental and theoretical data suggest that the aliphatic side chains play a significant role in determining the physical, transistor, and photovoltaic properties of the polymers. PaADSDTFBT-C-4 and PaADSDTFBT-C-8 exhibited organic-field-effect-transistor hole mobilities of 2.7 x 10(-2) and 1.0 x 10(-2) cm(2) V-1 s(-1), greatly outperforming that of PaADSDTFBT-C8C12 with a mobility of 5.4 X 10(-6) cm(2) V-1 s(-1). Polymer solar cells were fabricated on the basis of ITO/PEDOT:PSS/polymer:PC71BM/Ca/Al configuration. The efficiency decreased as the increase of bulkiness of the aliphatic side chains installed on DTFBT units (4.4% for PaADSDTFBT-C-4, 3.5% for PaADSDTFBT-C-8, 0.3% for PaADSDTFBT-C8C12). Atomic force microscopy images reveal that the degree of aggregation for the polymer:fullerene blends is influenced significantly by the bulkiness of aliphatic side chain installed on DTFBT. Noticeable aggregation was found for the PaADSDTFBT-C8C12:PC71BM blend. These results are in good agreement with the computational results elucidating that the intermolecular interactions between the polymers and PC71BM are sterically hindered by the bulky 2-octyldodecyl groups. This work not only presents a promising selenophene-based aADS building block but also provides insights into the side-chain engineering for donor-acceptor conjugated copolymers.
Angular-Shaped 4,9-Dialkyl - and -Naphthodithiophene-Based Donor-Acceptor Copolymers: Investigation of Isomeric Structural Effects on Molecular Properties and Performance of Field-Effect Transistors and Photovoltaics
(2015-10-14)
Cheng, Sheng-Wen
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Chiou, De-Yang
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Tsai, Che-En
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Liang, Wei-Wei
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Lai, Yu-Ying
Two angular-shaped 4,9-didodecyl -aNDT and 4,9-didodecyl -aNDT isomeric structures have been regiospecifically designed and synthesized. The distannylated -aNDT and -aNDT monomers are copolymerized with the Br-DTNT monomer by the Stille coupling to furnish two isomeric copolymers, PNDTDTNT and PNDTDTNT, respectively. The geometric shape and coplanarity of the isomeric -aNDT and -aNDT segments in the polymers play a decisive role in determining their macroscopic device performance. Theoretical calculations show that PNDTDTNT possesses more linear polymeric backbone and higher coplanarity than PNDTDTNT. The less curved conjugated main chain facilitates stronger intermolecular - interactions, resulting in more redshifted absorption spectra of PNDTDTNT in both solution and thin film compared to the PNDTDTNT counterpart. 2D wide-angle X-ray diffraction analysis reveals that PNDTDTNT has more ordered -stacking and lamellar stacking than PNDTDTNT as a result of the lesser curvature of the PNDTDTNT backbone. Consistently, PNDTDTNT exhibits a greater field effect transistor hole mobility of 0.214 cm(2) V-1 s(-1) than PNDTDTNT with a mobility of 0.038 cm(2) V-1 s(-1). More significantly, the solar cell device incorporating the PNDTDTNT:PC71BM blend delivers a superior power conversion efficiency (PCE) of 8.01% that outperforms the PNDTDTNT:PC71BM-based device with a moderate PCE of 3.6%.
Applications of functional fullerene materials in polymer solar cells
(2014-06-01)
Lai, Yu-Ying
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Cheng, Yen-Ju
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Hsu, Chain-Shu
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應用化學系
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Department of Applied Chemistry
Bulk heterojunction (BHJ) polymer solar cells (PSCs) on the basis of polymer: fullerene blends have delivered numerous impressive results in the last decade and thus have drawn much attention of the scientific and industrial communities. However, BHJ PSCs often suffer from several intrinsic problems, such as the low open-circuit voltage (V-oc), energetically-unfavorable and chemically-incompatible interfaces, and morphological phase separation of the polymer: fullerene blend driven by thermal treatment, hindering further advancement. In this review, we summarize the recent progress on applications of fullerene-based materials in the BHJ PSCs. Bis-adduct fullerenes possessing high-lying LUMO energy levels can substitute for mono-substituted fullerenes and higher Voc values can thus be achieved. Incorporation of an n-type fullerene interlayer between inorganic and organic active layers in either inverted or conventional PSCs can help in minimization of charge recombination losses at the interface and improvement of charge transfer from the active layer to the inorganic layer, thus resulting in superior PCEs. The optimal active-layer morphology can be maintained through several approaches, such as in situ polymerization of cross-linkable fullerenes, suppression of large-scale PC61BM aggregation by a polyethylene glycol-functionalized fullerene, supramolecular pentafluorophenyl-fullerene stabilization, and light-induced oligomerization of fullerenes. The morphological phase separation of the active-layer materials can thus be minimized. The research of employing fullerene materials will continue playing a critical role in BHJ PSCs. With further investigation and advancement in this field, it is expected that the ultimate goal of commercialization can be realized.
Bispentafluorophenyl-Containing Additive: Enhancing Efficiency and Morphological Stability of Polymer Solar Cells via Hand-Grabbing-Like Supramolecular Pentafluorophenyl-Fullerene Interactions
(2017-12-20)
Hung, Kai-En
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Tsai, Che-En
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Chang, Shao-Ling
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Lai, Yu-Ying
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Jeng, U-Ser
A new class of additive materials bis(pentafluorophenyl) diesters (BFEs) where the two pentafluorophenyl (C6F5) moieties are attached at the both ends of a linear aliphatic chain with tunable tether lengths (BFS, BF7, and BF13) were designed and synthesized. In the presence of BF7 to restrict the migration of fullerehe by hand-grabbing-like supramolecular interactions induced between the C6F5 groups and the surface of fullerene, the P3HT:PC61BM:BF7 device showed stable device characteristiCs after thermal heating at 150 degrees C for 25, 'IL The morphologies Of the active layers were systematically investigated by optical microscopy, grazing-incidence small-angle X-ray scattering (GISAXS), and atomic force microscopy. The tether length between the two C6F5 groups plays a pivotal role in controlling the intermolecular attractions. BF13 with a long and flexible tether might form a BF13-fullerene sandwich complex that fails to prevent fullerene's movement and aggregation, while BF5 with too short tether length decreases the possibility of interactions between the C6F5 groups and the fullerenes. BF7 with the optimal tether length has the best ability to stabilize the morphology. In sharp contrast, the nonfluorinated BP7 analogue without C6F5-C-60 physical interactions does not have the capability of morphological stabilization, unambiguously revealing the necessity of the C6F5 group. Most importantly, the function of BF7 can be also applied to the high-performance PffBT4BT-20D:PC71BM system, which exhibited an original PCE of 8.80%. After thermal heating at 85 degrees C for 200 h, the efficiency of the Pffi3T4BT-20D:PC71BM:BF7 device only decreased slightly to 7.73%, maintaining 88% of its original efficiency. To the best of our knowledge, this is the first time that the thermabdriven morphological evolution of the high-performance PffBT4BT-20D polymer has been investigated, and its morphological stability in the inverted device can be successfully preserved by the incorporation of BF7. This research also demonstrates that BF7 is not only effective with PC61BM but also to PC71BM.
Correlation between ferroelectricity and nitrogen incorporation of undoped hafnium dioxide thin films
(2020-06-01)
Luo, Jun-Dao
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Yeh, Yun-Tien
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Lai, Yu-Ying
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Wu, Chia-Feng
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Chung, Hao-Tung
The ferroelectric characteristics of undoped hafnium oxide (HfO2) in titanium nitride (TiN)/HfO2/TiN stacks exhibited improved remanent polarization by controlling the nitrogen gas flow during TiN deposition in this work. Electrical measurements revealed that samples with a higher N-2/(Ar + N-2) ratio obtained a higher remanent polarization of approximately 10 mu C/cm(2) at 2.5 V but exhibited a larger leakage current and less reliability. Among all the samples, the sample with a N-2/(Ar + N-2) ratio of 33% exhibited a relatively high remanent polarization of 12 mu C/cm(2) and excellent endurance over 10(8) cycles. Through X-ray photoelectron spectroscopy (XPS) analysis, it was observed that increasing the N-2 gas flow during TiN electrode deposition contributed to excessive N-diffusion, leading to the creation of more oxygen vacancies and subsequently to device failure. Therefore, controlling the appropriate N-2 gas flow during TiN deposition is crucial to enhance the ferroelectric characteristics of undoped HfO2. The results of this study may be applicable to future work on nonvolatile memory applications.
Formation of Nanostructured Fullerene Interlayer through Accelerated Self-Assembly and Cross-Linking of Trichlorosilane Moieties Leading to Enhanced Efficiency of Photovoltaic Cells
(2013-06-25)
Liang, Wei-Wei
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Chang, Chih-Yu
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Lai, Yu-Ying
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Cheng, Sheng-Wen
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Chang, Huan-Hsuan
A new cross-linkable fullerene material, bis(2-(trichlorosilyl)propyl)-malonate C-60 (TSMC), functionalized with two trichlorosilane groups, was easily synthesized by Pt-catalyzed olefin hydrosilylation. By making use of facile hydrolysis of the trichlorosilyl moieties, TSMC can be spontaneously self-assembled and cross-linked on the TiOx surface by a simple spin-coating processing without the aid of photoirradiation or post-thermal treatments. The rapid formation of self-assembled and crosslinked TSMC (SA-C-TSMC) effectively passivates the residual hydroxyl groups on the TiOx surface. More significantly, the solvent-resistant TSMC network features a nanostructured surface to provide extra charge-generating interfacial area and straight electron transport pathways. The device (ITO/TiOx/SA-C-TSMC/P3HT:PC61BM (1:1, w/w)/PEDOT:PSS/Ag) with this C-60 interlayer exhibited an efficiency of 3.9% which greatly outperformed the device without this layer. Furthermore, the strategy can also be effectively applied to the device (ITO/TiOx/PDITTDTBT:PC71BM(1:4, w/w)/MoOx/Ag) incorporating a conjugated polymer, poly(diindenothiophene-alt-dithienylbenzothiadizole) copolymer (PDITTDTBT). This device delivered a high efficiency of 5.8% which represents a 35% enhancement over the device without SA-C-TSMC. This new generation of trichlorosilane-based fullerene offers an easy and accelerated processing technique to produce efficient and cost-effective inverted solar cells.
Influences of the Non-Covalent Interaction Strength on Reaching High Solid-State Order and Device Performance of a Low Bandgap Polymer with Axisymmetrical Structural Units
(2013-05-07)
Jheng, Jyun-Fong
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Lai, Yu-Ying
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Wu, Jhong-Sian
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Chao, Yi-Hsiang
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Wang, Chien-Lung
A high organic field-effect transistor mobility (0.29 cm(2)V(-1)s(-1)) and bulk-heterojunction polymer solar cell performance (PCE of 6.82%) have been achieved in a low bandgap alternating copolymer consisting of axisymmetrical structural units, 5,6-difluorobenzo-2,1,3-thiadiazole. Introducing the fluorine substituents enhanced intermolecular interaction and improved the solid-state order, which consequently resulted in the highest device performances among the 2,1,3-thiadiazole-quarterthiophene based alternating copolymers.
Interface Engineering to Enhance the Efficiency of Conventional Polymer Solar Cells by Alcohol-/Water-Soluble C-60 Materials Doped with Alkali Carbonates
(2013-06-12)
Lai, Yu-Ying
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Shih, Ping-I
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Li, Yi-Peng
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Tsai, Che-En
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Wu, Jhong-Sian
Two new C-60-based n-type materials, EGMC-OH and EGMC-COOH, functionalized with hydrophilic triethylene glycol groups (TEGs), have been synthesized and employed in conventional polymer solar cells. With the assistance of the TEG-based surfactant, EGMC-OH and EGMC COOH can be dissolved in highly polar solvents to implement the polar/nonpolar orthogonal solvent strategy, forming an electron modification layer (EML) without eroding the basis of ITO/PEDOT:PSS/P3HT:PC61M/EML/Ca/Al configuration with the insertion of the EGMC OH and EGMC COOH EML between the active layer and the electrode have thus been successfully realized by cost-effective solution processing techniques. Moreover, the electron conductivity of the EML can be improved by incorporating alkali carbonates into the EGMC-COOH EML. Compared to the pristine device with a PCE of 3.61%, the devices modified by the Li2CO3-doped EGMC-COOH EML achieved a highest PCE of 4.29%. Furthermore, we demonstrated that the formation of the EGMC-COOH EML can be utilized as a general approach in the fabrication of highly efficient multilayer conventional devices. With the incorporation of the EGMC-COOH doped with 40 wt % Li2CO3, the PCDCTBT-C8:PC17BM-based device exhibited a superior PCE of 4.51%, which outperformed the corresponding nonmodified device with a PCE of 3.63%.
Morphological Stabilization by Supramolecular Perfl uorophenyl-C-60 Interactions Leading to Effi cient and Thermally Stable Organic Photovoltaics
(2014-03-01)
Liao, Ming-Hung
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Tsai, Che-En
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Lai, Yu-Ying
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Cao, Fong-Yi
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Wu, Jhong-Sian
A new PC61BM-based fullerene, [6,6]-phenyl-C-61 butyric acid pentafluorophenyl ester (PC61BPF) is designed and synthesized. This new n-type material can replace PC61BM to form a P3HT:PC61BPF binary blend or serve as an additive to form a P3HT:PC61BM:PC61BPF ternary blend. Supramolecular attraction between the pentafluorophenyl group of PC61BPF and the C-60 cores of PC61BPF/PC61BM can effectively suppress the PC61BPF/PC61BM materials from severe aggregation. By doping only 8.3 wt% PC61BPF, device PC(61)BP(F)651 exhibits a PCE of 3.88% and decreases slightly to 3.68% after heating for 25 h, preserving 95% of its original value. When PC61BP with non-fluorinated phenyl group is used to substitute PC61BPF, the stabilizing ability disappears completely. The efficiencies of PC(61)BP651 and PC(61)BP321 devices significantly decay to 0.44% and 0.11%, respectively, after 25 h isothermal heating. Most significantly, this strategy is demonstrated to be effective for a blend system incorporating a low band-gap polymer. By adding only 10 wt% PC61BPF, the PDTBCDTB:PC71BM-based device exhibits thermally stable morphology and device characteristics. These findings demonstrate that smart utilization of supramolecular interactions is an effective and practical strategy to control morphological evolution.
Reducing Regioisomers of Fullerene-Bisadducts by Tether-Directed Remote Functionalization: Investigation of Electronically and Sterically Isomeric Effects on Bulk-Heterojunction Solar Cells
(2014-01-22)
Liao, Ming-Hung
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Lai, Yin-Yu
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Lai, Yu-Ying
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Chen, Yen-Ting
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Tsai, Che-En
C-60 bis-adduct containing a mixture of regio-isomers with different LUMO energy levels and steric geometries could greatly affect the morphological and bulk properties. To investigate the regio-isomer effect on solar cell performance, we have successfully designed and synthesized a regio-selective 4-acetatephenyl-4'-methylphenylmethano C-60 bis-adduct (S-APM-CBA) by "tether-directed remote functionalization" strategy and a random 4-acetatephenyl-4'-methylphenylmethano C-60 bis-adduct denoted as R-APM-CBA by traditional cyclopropanation. The dramatic reduction in the number of regio-isomers in S-APM-CBA is confirmed by the H-1 NMR and HPLC measurements and theoretical calculation. Compared to the R-APM-CBA-based device with a J(sc) of 6.63 mA/cm(2), an FF of 44.3% and a PCE of 2.46%, the device using S-APM-CBA yielded a much lower J(sc) of 1.48 mA/cm(2), an FF of 32.2%, and a PCE of 0.38%. Consistently, the electron-only device using S-AMP-CBA exhibited lower electron mobility than the R-AMP-CBA-based device. These results imply that the electronic shallow-trap effect ascribed to the LUMO energy variations turned out to be insignificant in the AMP-CBA system. The lower efficiency and mobility of S-AMP-CBA might due to the assumption that the most probable trans-4-III isomer in S-AMP-CBA prevents the intermolecular facial contact of fullerenes, thereby hindering the electron transporting. Furthermore, the nanomorphology of S-AMP-CBA and R-AMP-CBA active layers could be different because of their different three-dimensional structures. This research demonstrated that steric effect of regio-isomers in a given C-60 bis-adduct is more crucial than electronic shallow-trap effect.
Regio- and stereo-selective [4+4] photodimerization of angular-shaped dialkyltetracenedithiophene
(2019-01-11)
Hsu, Tze-Gang
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Chou, Hsiao-Chieh
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Liang, Ming-Ju
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Lai, Yu-Ying
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Cheng, Yen-Ju
Angular-shaped dialkyltetracenedithiophenes (aTDTs) undergo [4+4] photodimerization in solution to form a butterfly-shaped skeleton. This reaction proceeds in a regio- and stereo-selective manner, forming only a single planosymmetric syn-[2,2]-daTDT out of six possible products. The photocycloaddition of aTDTs can take place topochemically in the thin-film state while maintaining regio- and stereo-selectivity. Stronger aliphatic dispersion forces and - interactions play important roles in forming the eclipsed dimeric complex that leads to the syn-[2,2]-daTDT isomer.
Self-assembled tri-, tetra- and penta-ethylene glycols as easy, expedited and universal interfacial cathode-modifiers for inverted polymer solar cells
(2016-06-14)
Cao, Fong-Yi
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Lai, Yu-Ying
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Chen, Yung-Lung
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Cheng, Yen-Ju
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應用化學系
Non-conjugated triethylene glycol (3-EG), tetraethylene glycol (4-EG) and pentaethylene glycol (5-EG) are presented as new cathode modification materials to achieve high-performance inverted-PCSs. By spin-coating from a non-chlorinated solvent, these small molecules can self-assemble on ITO via surface coordination and hydrogen bonding to form an ultra-thin layer. Theoretical simulations reveal that the coordination of oxygen atoms in the EG molecules to indium moieties on the ITO surface is the major mechanism in inducing interfacial dipoles, thereby reducing the work function (W-F) of ITO for efficient electron collection. Based on the PBDTTT-EFT:PC71BM blend, the bulk heterojunction device using the 5-EG layer exhibited a higher short-circuit current density (J(sc)) of 15.27 mA cm(-2), fill factor (FF) of 0.69, and power conversion efficiency (PCE) of 8.46%, which are better than those of the corresponding devices using either inorganic ZnO or non-conjugated poly(ethylene oxide) (PEO) as the cathode buffer layer. More importantly, this simple and expedited strategy is also demonstrated to be universally applicable to various p-type conjugated polymers. The EG oligomers with well-defined chemical structures have the advantages of easy availability, simple processability and good device reproducibility, which are crucial keys for future commercialization using large-scale roll-to-roll production.
Side-chain modulation of dithienofluorene-based copolymers to achieve high field-effect mobilities
(2017-04-01)
Lee, Chia-Hao
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Lai, Yu-Ying
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Hsu, Jhih-Yang
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Huang, Po-Kai
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Cheng, Yen-Ju
A ladder-type dithieno[3,2-b: 6,7-b'] fluorene (DTF), where the central fluorene is fused with two outer thiophene rings at its 2,3- and 6,7-junctions, is developed. The pentacyclic DTF monomers were polymerized with dithienodiketopyrrolopyrrole (DPP) acceptors to afford three alternating donor-acceptor copolymers PDTFDPP16, PDTFDPP20, and PDTFDPP32 incorporating different aliphatic side chains (R-1 group at DTF; R-2 group at the DPP moieties). The side-chain variations in the polymers play a significant role in determining not only the intrinsic molecular properties but also the intermolecular packing. As evidenced by the 2-dimensional GIXS measurements, PDTFDPP16 with octyl (R-1) and 2-ethylhexyl (R-2) side chains tends to align in an edge-on pi-stacking orientation, whereas PDTFDPP20 using 2-butyloctyl (R-1) and 2-ethylhexyl (R-2) adopts a predominately face-on orientation. PDTFDPP32 with the bulkiest 2-butyloctyl (R-1) and 2-octyldodecyl (R-2) side chains shows a less ordered amorphous character. The OFET device using PDTFDPP20 with a face-on orientation determined by GIXS measurements achieved a high hole-mobility of up to 5 cm(2) V-1 s(-1). The high rigidity and coplanarity of the DTF motifs play an important role in facilitating intramolecular 1-dimensional charge transport within the polymer backbones. The implementation of main-chain coplanarity and side-chain engineering strategies in this research provides in-depth insights into structure-property relationships for guiding development of high-mobility OFET polymers.
Synthesis and field-effect transistor properties of a diseleno[3,2-b:2 \',3 \'-d]silole-based donor-acceptor copolymer: investigation of chalcogen effect
(2016)
Pao, Yu-Chieh
;
Yang, Cheng-Tai
;
Lai, Yu-Ying
;
Huang, Wen-Chia
;
Hsu, Chain-Shu
We have designed and synthesized a tricyclic diseleno[3,2-b:2\',3\'-d]silole (DSS) wherein the 3,3\'-position of a biselenophene is bridged by a dioctylsilyl moiety. The distannylated DSS was copolymerized with a diketopyrrolopyrrole (DPP) acceptor to form a donor-acceptor copolymer PDSSDPP. The thiophene-based dithieno[3,2-b:2\',3\'-d]silole (DTS) monomer and its corresponding copolymer PDTSDPP are also prepared as references for investigation of the chalcogen effect. Compared to PDTSDPP, PDSSDPP exhibits a more red-shifted absorption spectrum, a higher-lying HOMO energy level, and closer interchain packing associated with the more polarizable Se atom to induce stronger intermolecular interactions. The selenophene-based PDSSDPP shows a mobility of 2.47 x 10(-2) cm(2) V-1 s(-1), which is nearly one order magnitude higher than the thiophene-based PDTSDPP with a mobility of 3.89 x 10(-3) cm(2) V-1 s(-1). This result suggests that the DSS unit and its polymers are promising for OFET applications.
Synthesis and Isomeric Effects of Ladder-Type Alkylated Terbenzodithiophene Derivatives
(2016-03-18)
Chen, Yung-Lung
;
Hsu, Jhih-Yang
;
Lin, Fang-Yu
;
Lai, Yu-Ying
;
Chou, Hsiao-Chieh
A new class of heptacyclic ladder-type terbenzodithiophene (TBDT) structures merging three fused benzodithophenes was developed. Two TBDT conjugated isomers, named as syn-TBDT and anti-TBDT, where the two thienyl rings in the outmost BDT units are in the syn- and anti-fashion, are designed. Two decyl groups are introduced to their 6,13 and 7,14-positions to form four isomeric 6,13-syn-TBDT, 7,14-syn-TBDT, 6,13-anti-TBDT, and 7,14-anti-TBDT structures which are constructed by the DBU-induced 6-benzannulation involving propargyl-allenyl isomerization of the dieneyne moieties in the corresponding precursors followed by 6 pi-electro-cyclization/aromatization, while isomeric TD-syn-TBDT and TD-anti-TBDT with four decyl groups substituted at 6,7,13,14-positions are synthesized via palladium-catalyzed dialkylacetylene insertion/C-H arylation of the corresponding iodobiaryl precursors. The intrinsic properties can be modulated by molecular manipulation of the main-chain and side-chain isomeric structures. anti-TBDT derivatives exhibit higher melting points, larger bandgaps, stronger intermolecular interactions, and higher mobility than the corresponding syn-TBDT analogues. These molecules can be further utilized as building blocks to make various TBDT-based materials for optoelectronic applications.
Synthesis and Molecular Properties of Four Isomeric Dialkylated Angular-Shaped Naphthodithiophenes
(2013-10-18)
Cheng, Sheng-Wen
;
Chiou, De-Yang
;
Lai, Yu-Ying
;
Yu, Ruo-Han
;
Lee, Chia-Hao
A new strategy to synthesize 4,9- and 5,10-dialkylated alpha-aNDTs as well as 4,9- and 5,10-dialkylated beta-aNDTs is described. Four isomeric precursors with different dithienyl-ene-diyne arrangements undergo base-induced double 6 pi-cyclization to construct the central naphthalene cores, leading to the formation of the regiospecific products. These 2,7-distannylated dialkylated aNDT-based monomers can be used for Stille cross-coupling to produce promising conjugated materials for various optoelectronic applications.