Browsing by Author "Cheng, Yen-Ju"

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2-Dimensional cross-shaped tetrathienonaphthalene-based ladder-type acceptor for high-efficiency organic solar cells
(2020-06-28)
Chang, Shao-Ling
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Cao, Fong-Yi
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Huang, Kuo-Hsiu
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Lee, Wei-Liang
;
Lee, Meng-Hsun
AnNC-FICnonfullerene acceptor, using a didodecylnaphthodithiophene (NDT) embedded octacyclic ladder-type donorNC, had been described previously. In this work, a new cross-shapedTC-FICnonfullerene acceptor is designed by substitution of the NDT unit in theNCskeleton with a 2-dimensional didodecyltetrathienonaphthalene (TTN) unit. The 2-dimensionalTC pi-system with two vertically fused thiophenes strengthens the electron-donating ability, promotes pi-electron delocalization and enhances intramolecular donor-acceptor charge transfer and intermolecular pi-pi interactions. As a result,TC-FICshows more red-shifted and widened absorption compared to theNC-FICcounterpart. The PBDB-T:TC-FICdevice exhibits a higher efficiency of 11.6% which greatly outperformed the corresponding PBDB-T:NC-FICdevice with an efficiency of 7.52%. The dramatic 54% enhancement in efficiency is ascribed to the improved light-harvesting ability and enhanced charge mobilities which are benefited from the central 2-dimensionalTTNmoiety. By incorporatingPC(71)BMto improve absorption and electron transport, the ternary-blend PBDB-T : TC-FIC : PC(71)BMdevice (1 : 1 : 1 in wt%) achieves a highest PCE of 13.49% with an enhancedJ(sc)of 23.80 mA cm(-2), an FF of 64.4%, and aV(oc)of 0.88 V.
A crosslinked fullerene matrix doped with an ionic fullerene as a cathodic buffer layer toward high-performance and thermally stable polymer and organic metallohalide perovskite solar cells
(2015-01-01)
Chao, Yi-Hsiang
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Huang, Yi-You
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Chang, Jen-Yun
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Peng, Shih-Hao
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Tu, Wei-Yi
In this study, we developed a new cathodic buffer layer consisting of a cross-linked [6,6]-phenyl-C-61-butyric styryl dendron ester (C-PCBSD) matrix and an ionic FPI dopant. The incorporation of FPI can improve the electron mobility via an anion induced charge transfer (AIET) mechanism, while maintaining the solvent-resistant properties of the crosslinked layer. ZnO combined with the C-PCBSD/FPI layer can effectively and universally improve the performance of bulk-heterojunction polymer solar cells (BHJPSCs), planar heterojunction polymer solar cells (PHJPSCs), and organic metallohalide perovskite solar cells (OMPSCs). Furthermore, the insertion of the C-PCBSD/FPI layer can improve the thermal stability of the device by preventing the residual moisture in ZnO from diffusing into the CH3NH3PbI3 layer in OMPSCs.
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.
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
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Wu, Jhong-Sian
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Lin, Tai-Yen
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Kao, Wei-Shun
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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.
A Versatile Fluoro-Containing Low-Bandgap Polymer for Efficient Semitransparent and Tandem Polymer Solar Cells
(2013-10-01)
Chang, Chih-Yu
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Zuo, Lijian
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Yip, Hin-Lap
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Li, Yongxi
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Li, Chang-Zhi
The versatility of a fluoro-containing low band-gap polymer, poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7-(5-fluoro-2,1,3-benzothia-diazole)] (PCPDTFBT) in organic photovoltaics (OPVs) applications is demonstrated. High boiling point 1,3,5-trichlorobenzene (TCB) is used as a solvent to manipulate PCPDTFBT:[6,6]-phenyl-C-71-butyric acid methyl ester (PC71BM) active layer morphology to obtain high-performance single-junction devices. It promotes the crystallization of PCPDTFBT polymer, thus improving the charge-transport properties of the active layer. By combining the morphological manipulation with interfacial optimization and device engineering, the single-junction device exhibits both good air stability and high power-conversion efficiency (PCE, of 6.6%). This represents one of the highest PCE valuesfor cyclopenta[2,1-b;3,4-b']dithiophene (CPDT)-based OPVs. This polymer is also utilized for constructing semitransparent solar cells and double-junction tandem solar cells to demonstrate high PCEs of 5.0% and 8.2%, respectively.
Alternating and Diblock Donor-Acceptor Conjugated Polymers Based on Diindeno[1,2-b:2 ',1 '-d]thiophene Structure: Synthesis, Characterization, and Photovoltaic Applications
(2010)
Chen, Chiu-Hsiang
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Cheng, Yen-Ju
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Dubosc, Martin
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Hsieh, Chao-Hsiang
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Chu, Cheng-Che
Pentacyclic diindeno[1,2':2',1'-d]thiophene (DIDT) unit is a rigid and coplanar conjugated molecule. To the best of our knowledge, this attractive molecule has never been incorporated into a polymer and thus its application in polymer solar cells has never been explored. For the first time, we report the detailed synthesis of the tetra-alkylated DIDT molecule leading to its dibromo-and diboronic ester derivatives, which are the key monomers for preparation of DIDT-based polymers. Two donor-acceptor alternating polymers, poly(diindenothiophene-alt-benzothiadiazole) PDIDTBT and poly-(diindenothiophene-alt-dithienylbenzothiadiazole) PDIDTDTBT, were synthesized by using Suzuki polymerization. Copolymer PTDIDTTBT was also prepared by using Stille polymerization. Although PTDIDTTBT is prepared through a manner of random polymerization, we found that the different reactivities of the dibromo-monomers lead to the resulting polymer having a block copolymer arrangement. With the higher structural regularity, PTDIDTTBT, symbolized as (thiophene-alt-DIDT)(0.5)-block-(thiophene-alt-BT)(0.5), shows the higher degree of crystallization, stronger pi-pi stacking, and broader absorption spectrum in the solid state, as compared to its alternating PDIDTDTBT analogue. Bulk heterojunction photovoltaic cells based on ITO/PEDOT:PSS/polymer:PC(71)BM/Ca/Al configuration were fabricated and characterized. PDIDTDTBT/PC(71)BM and PTDIDTTBT/PC(71)BM systems exhibited promising power-conversion efficiencies (PCEs) of 1.65% and 2.00%, respectively. Owing to the complementary absorption spectra, as well as the compatible structures of PDIDTDTBT and PTDIDTTBT, the PCE of the device based on the ternary blend PDIDTDTBT/PTDIDTTBT/PC(71)BM was further improved to 2.40%.
Alternating Copolymers Incorporating Cyclopenta[2,1-b:3,4-b ']dithiophene Unit and Organic Dyes for Photovoltaic Applications
(2011-04-15)
Cheng, Yen-Ju
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Hung, Lung-Chang
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Cao, Fong-Yi
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Kao, Wei-Shun
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Chang, Chih-Yu
We have synthesized six p-type copolymers, CPDT-co-TPADCN, CPDT-co-TPADTA, CPDT-co-TPATCN, CPDT-coDFADCN, CPDT-co-DFADTA, and CPDT-co-DFATCN, consisting of a cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) unit and an organic dye in an alternating arrangement. Triphenylamine (TPA) or difluorenylphenyl amine (DFA) units serve as the electron donors, whereas dicyanovinyl (DCN), 1,3-diethyl-2-thiobarbituric acid, or tricyanovinyl (TCN) units act as the electron acceptors in the dyes. The target polymers were prepared via Stille coupling, followed by postfunctionalization to introduce the electron acceptors to the side chains. Because of the strongest withdrawing ability of TCN acceptor to induce efficient intramolecular charge transfer, CPDT-co-TPATCN and CPDT-co-DFATCN exhibit the broader absorption spectra covering from 400 to 900 nm and the narrower optical band gaps of 1.34 eV. However, the CPDT-co-TPATCN:PC(71)BM and CPDT-co-DFATCN:PC(71)BM based solar cells showed the power conversion efficiencies (PCEs) of 0.22 and 0.31%, respectively, due to the inefficient exciton dissociation. The DFA-based polymers possess deeper-lying HOMO energy levels than the TPA-based polymer analogues, leading to the higher V(oc) values and better efficiencies. The device based on CPDT-co-DFADTA:PC(71)BM blend achieved the best PCE of 1.38% with a V(oc) of 0.7 V, a J(sc) of 4.57 mA/cm(2), and a fill factor of 0.43. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49:1791-1801, 2011
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%.
Angular-Shaped 4,9-Dialkylnaphthodithiophene-Based Donor-Acceptor Copolymers for Efficient Polymer Solar Cells and High-Mobility Field-Effect Transistors
(2015-04-14)
Cheng, Sheng-Wen
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Tsai, Che-En
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Liang, Wei-Wei
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Chen, Yung-Lung
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Cao, Fong-Yi
Although the tetracyclic angular-shaped naphthodithiophenes (aNDTs) derivatives are an emergent building block for constructing promising semiconductor conjugated polymers, the absence of aliphatic side chains as solubilizing groups on the aNDTs greatly restricted their further application toward polymer synthesis. To create a new class of aNDT-based polymers for widespread applications in solution-processable OFETs and PSCs, side-chain engineering of the aNDT-based structures plays a pivotal role in improving solubility and optimizing electronic/steric properties associated with the resultant solar cell characteristics. In this research, we developed an efficient and straightforward methodology to construct the angular naphthodithophene core with regiospecific introduction of two aliphatic chains at its 4,9-positions via a base-induced double 6p-cyclization. For the first time, the corresponding 2,7-distannylated-4,9-dialkylated aNDT monomers were polymerized with FBT and DPP acceptors to make two new PaNDTDTFBT and PaNDTDPP donor-acceptor copolymers. The photovoltaic devices based on the PaNDTDTFBT:PC71BM blend not only showed a promising PCE of 6.52% with conventional configuration but also achieved a higher PCE of 6.86% with inverted configuration. Moreover, PaNDTDPP with strong intermolecular interaction achieved a high FET hole mobility of 0.202 cm(2) V-1 s(-1).
Angular-Shaped 4,9-Dialkylnaphthodithiophene-Based Octacyclic Ladder-Type Non-Fullerene Acceptors for High Efficiency Ternary-Blend Organic Photovoltaics
(2018-08-14)
Cao, Fong-Yi
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Huang, Wen-Chia
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Chang, Shao-Ling
;
Cheng, Yen-Ju
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應用化學系
An angular-shaped 4,9-didodecylnaphthodithiophene-based octacyclic ladder-type structure was developed. This new ladder-type donor (LD) was coupled with electron withdrawing IC and FIC units to form two A-LD-A type non-fullerene acceptor materials, NCIC and NCFIC. NCIC and NCFIC as the n-type acceptors are blended with a p-type donor PBDB-T to form the complementary absorption and suitable energy level alignments. The binary-blend PBDB-T:NCIC and PBDB-T:NCFIC devices achieved an efficiency of 7.3% and 7.5%, respectively. PC71BM was incorporated to form D-1:A(1):A(2) ternary blends which further strengthen the absorption at shorter wavelengths. Introduction of PC71BM not only efficiently improves the absorption but also provides multiple channels for exciton dissociation and electron transport to dramatically improve J(sc). It is interesting to find that the V-oc of the ternary-blend devices is reversely in proportional to the added amount of PC71BM. The device using the PBDB-T:NCIC:PC71BM (1:1:1 in wt %) showed an improved PCE of 8.32%. Moreover, the optimized device using the PBDB-T:NCFIC:PC71BM (1:1:1.5 in wt %) blend achieved the highest efficiency of 9.18%.
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.
Carbazole-based heptacyclic arenes with carbon, silicon, and nitrogen bridges: Synthesis, molecular properties and photovoltaic applications
(2012-03-25)
Wu, Jhong-Sian
;
Cheng, Yen-Ju
;
Hsu, Chain-Shu
;
應用化學系
;
Department of Applied Chemistry
Carbazole-Based Ladder-Type Heptacylic Arene with Aliphatic Side Chains Leading to Enhanced Efficiency of Organic Photovoltaics
(2011-05-10)
Cheng, Yen-Ju
;
Wu, Jhong-Sian
;
Shih, Ping-I
;
Chang, Chih-Yu
;
Jwo, Pei-Chi
By utilizing Friedel-Crafts cyclization, we have successfully designed and synthesized a ladder-type heptacyclic carbazole-dicyclopentathiophene (CDCT-C8) unit in which two outer thiophene subunits are covalently fastened to the central 2,7-carbazole core. The nitrogen-directing effect of the carbazole unit facilitates the intrarnolecular cydization and thereby suppresses the acid-induced dehydration, allowing us to incorporate two octyl side chains on the cyclopentadiene rings in good chemical yield. The distannyl-CDCT-C8 building block was copolymerized with benzothiadiazole (BT), dithienylbenzothiadiazole (DTBT), dithienyldiketopyrrolopyrrole (DTDPP) and quinoxaline (QX) units by Stile polymerization to afford four alternating donor acceptor copolymers, PCDCTBT-C8, PCDCTDTBT-C8, PCDCTDTDPP-C8 and PCDCTQX-C8, respectively. The device based on the PCDCTBT-C8:PG7IBM (1:3 in wt%) blend exhibited a V(oc) of 0.74 V, a J(sc) of 10.3 mA/cm(2), a FF of 60%, delivering an impressive PCE of 4.6%. This value represents one of the best performances among carbazole-based conjugated polymers in the literatures. The corresponding PCDCTBT-C8 :PC(71)BM blend showed a high hole mobility of 1.2 x 10(-3) cm(2) V(-1) s(-1), which is in good agreement with its high current density and fill factor. This improved performance is associated with the modification of the aliphatic side chains on the CDCT structure to optimize the interchain interactions for enhanced charge transporting. The devices based on PCDCTDTBT-C8, PCDCTDTDPP-C8 and PCDCTQX-C8 polymers also displayed promising efficiencies of 3.5%, 2.4%, and 1.8%, respectively.
Combination of Indene-C(60) Bis-Adduct and Cross-Linked Fullerene Interlayer Leading to Highly Efficient Inverted Polymer Solar Cells
(2010-12-15)
Cheng, Yen-Ju
;
Hsieh, Chao-Hsiang
;
He, Youjun
;
Hsu, Chain-Shu
;
Li, Yongfang
A poly(3-hexylthiophene) (P3HT)-based inverted solar cell using indene-C(60) bis-adduct (ICBA) as the acceptor achieved a high open-circuit voltage of 0.82 V due to ICBA's higher-lying lowest unoccupied molecular orbital level, leading to an exceptional power-conversion efficiency (PCE) of 4.8%. By incorporating a cross-linked fullerene interlayer, C-PCBSD, to further modulate the interface characteristics, the ICBA:P3HT-based inverted device exhibited an improved short-circuit current and fill factor, yielding a record high PCE of 6.2%.
Combination of Indene-C-60 Bis-Adduct and Cross-Linked Fullerene Interlayer Leading to Highly Efficient Inverted Polymer Solar Cells
(2010-12-15)
Cheng, Yen-Ju
;
Hsieh, Chao-Hsiang
;
He, Youjun
;
Hsu, Chain-Shu
;
Li, Yongfang
A poly(3-hexylthiophene) (P3HT)-based inverted solar cell using indene-C-60 bis-adduct (ICBA) as the acceptor achieved a high open-circuit voltage of 0.82 V due to ICBA's higher-lying lowest unoccupied molecular orbital level, leading to an exceptional power-conversion efficiency (PCE) of 4.8%. By incorporating a cross-linked fullerene interlayer, C-PCBSD, to further modulate the interface characteristics, the ICBA:P3HT-based inverted device exhibited an improved short-circuit current and fill factor, yielding a record high PCE of 6.2%.