Browsing by Author "Chen, Chiu-Hsiang"

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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
;
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%.
Dithienocyclopentathieno[3,2-b]thiophene Hexacyclic Arene for Solution-Processed Organic Field-Effect Transistors and Photovoltaic Applications
(2012-04-01)
Cheng, Yen-Ju
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Chen, Chiu-Hsiang
;
Lin, Tai-Yen
;
Hsu, Chain-Shu
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應用化學系
We have developed a ladder-type dithienocyclopentathieno[3,2-b]thiophene (DTCTT) hexacyclic unit in which the central thieno[3,2-b]thiophene ring was covalently fastened to two adjacent thiophene rings through carbon bridges, thereby forming two connected cyclopentadithiophene (CPDT) units in a hexacyclic coplanar structure. This stannylated Sn-DTCTT building block was copolymerized with three electron-deficient acceptors, dibromo-thieno[3,4-c]pyrrole-4,6-dione (TPD), dibromo-benzothiadiazole (BT), and dibromo-phenanthrenequinoxaline (PQX), by Stille polymerization, thereby furnishing a new class of alternating donoracceptor copolymers: PDTCTTTPD, PDTCTTBT, and PDTCTTPQX, respectively. Field-effect transistors based on PDTCTTPQX and PDTCTTBT yielded high hole mobilities of 0.017 and 0.053 cm2?V-1?s-1, respectively, which are among the highest performances among amorphous donoracceptor copolymers. A bulk heterojunction solar cell that incorporated PDTCTTTPD with the lower-lying HOMO energy level delivered a higher Voc value of 0.72 V and a power conversion efficiency (PCE) value of 2.59?%.
Donor-Acceptor Random Copolymers Based on a Ladder-Type Nonacyclic Unit: Synthesis, Characterization, and Photovoltaic Applications
(2011-11-08)
Chen, Chiu-Hsiang
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Cheng, Yen-Ju
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Chang, Chih-Yu
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Hsu, Chain-Shu
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應用化學系
We have developed a ladder-type multifused thienyl-phenylene-thienylene-phenylene-thienyl (TPTPT) unit where each thiophene ring is covalently fastened with the adjacent benzene rings by a carbon bridge, forming four cyclopentadiene rings embedded in a nonacyclic structure. This rigid and coplanar TPTPT building block was copolymerized with electron-deficient acceptors, dibromobenzothiadiazole (BT) or dibromodithienyldiketopyrrolopyrrole (DPP), via Stille polymerization. By varying the feed ratio of the monomers, a new series of random copolymers PTPTPTBT11, PTPTPTBT12, PTPTPTDPP11, PTPTPTDPP12, and PTPTPTDPP13 with tunable optical and electronic properties were prepared. The PTPTPTDPP12/PC(71)BM (1:4, w/w) based device exhibited the highest short circuit current (J(sc)) of 10.78 mA/cm(2) with a good power conversion efficiency (PCE) of 4.3% due to the much boarder absorption ability and the highest hole mobility of PTPTPTDPP12. The devices based on PTPTPTDPP13, PTPTPTDPP11, PTPTPTBT12, and PTPTPTBT11 polymers also displayed promising efficiencies of 4.1%, 3.6%, 3.1%, and 2.8%, respectively. Most importantly, PTPTPTDPP12 has been demonstrated as a superior low-band-gap material for polymer solar cell with inverted architecture, achieving a high PCE of 5.1%.
Highly Efficient and Stable Inverted Polymer Solar Cells Integrated with a Cross-Linked Fullerene Material as an Interlayer
(2010-04-07)
Hsieh, Chao-Hsiang
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Cheng, Yen-Ju
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Li, Pei-Jung
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Chen, Chiu-Hsiang
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Dubosc, Martin
A novel PCBM-based n-type material, [6,6]-phenyl-C(61)-butyric styryl dendron ester (PCBSD). functionalized with a dendron containing two styryl groups as thermal cross-linkers, has been rationally designed and easily synthesized. In situ cross-linking of PCBSD was carried out by heating at a low temperature of 160 degrees C for 30 min to generate a robust, adhesive, and solvent-resistant thin film. This cross-linked network enables a sequential active layer to be successfully deposited on top of this interlayer to overcome the problem of interfacial erosion and realize a multilayer inverted device by all-solution processing. An inverted solar cell device based on an ITO/ZnO/C-PCBSD/P3HT:PCBM/PEDOT:PSS/Ag configuration not only achieves enhanced device characteristics, with an impressive PCE of 4.4%, but also exhibits an exceptional device lifetime without encapsulation; it greatly outperforms a reference device (PCE = 3.5%) based on an ITO/ZnO/P3HT:PCBM/PEDOT:PSS/Ag configuration without the interlayer. This C-PCBSD interlayer exerts multiple positive effects on both P3HT/C-PCBSD and PCBM/C-PCBSD localized heterojunctions at the interface of the active layer, including improved exciton dissociation efficiency, reduced charge recombination, decreased interface contact resistance, and induction of vertical phase separation to reduce the bulk resistance of the active layer as well as passivation of the local shunts at the ZnO interface. Moreover, this promising approach can be applied to another inverted solar cell, ITO/ZnO/C-PCBSD/PCPDTBT:PC(71)BM/PEDOT:PSS/Ag, using PCPDTBT as the p-type low-band-gap conjugated polymer to achieve an improved PCE of 3.4%. Incorporation of this cross-linked C(60) interlayer could become a standard procedure in the fabrication of highly efficient and stable multilayer inverted solar cells.
Ladder-Type Nonacyclic Structure Consisting of Alternate Thiophene and Benzene Units for Efficient Conventional and Inverted Organic Photovoltaics
(2011-11-22)
Cheng, Yen-Ju
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Chen, Chiu-Hsiang
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Lin, Yu-Shun
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Chang, Chih-Yu
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Hsu, Chain-Shu
A ladder-type nonacyclic thienyl-phenylene-thienylene-phenylene-thienyl TPTPT unit, consisting of alternate interfused thiophene and benzene units, is designed and synthesized. This multifused distannyl-TPTPT monomer was polymerized with two electron-deficient acceptors, 4,7-dibromo-2,1,3-benzothiadiazole BT and 5,8-dibromo-2,3-diphenylquinoxaline QX monomers, by Stile coupling reaction to afford two alternating donor acceptor copolymers, PTPTPTBT and PTPTPTQX, respectively. Because of the covalent planarization of the conjugated framework, PTPTPTBT simultaneously possess excellent solubilities for solution-processability, low bandgaps with suitable position of HOMO/LUMO energy levels, and high hole mobilities. The devices based on the PTPTPTBT/PC(71)BM blend not only showed a promising PCE of 5.3% with conventional configuration but also achieved a high PCE of 5.9% with inverted configuration. This value is among the highest performance from the inverted solar cells incorporating a donor acceptor low bandgap polymer.
Self-Assembled and Cross-Linked Fullerene Interlayer on Titanium Oxide for Highly Efficient Inverted Polymer Solar Cells
(2011-03-22)
Cheng, Yen-Ju
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Cao, Fong-Yi
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Lin, Wei-Cheng
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Chen, Chiu-Hsiang
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Hsieh, Chao-Hsiang
We have successfully designed and synthesized two oxetane-functionalized fullerene derivatives, [6,6]-phenyl-C(61)-butyric oxetane ester (PCBO) and [6,6]-phenyl-C(63)-butyric oxetane dendron ester (PCBOD). We demonstrated that the oxetane functionality with neutral nature can anchor onto the TiO(x) surface via cationic ring-opening reaction under thermal and UV treatment, as evidenced by contact angle measurement and X-ray photoelectron spectroscopy. The self-assembly of PCBO, functionalized with one oxetane group, on the TiO(x) surface forms an adhesive monolayer with intimate contact. Inverted bulk-heterojunction device B [ITO/TiO(x)/SA-PCBO/P3HT:PCBM (1:1 w/w)/MoO(3)/Ag, where ITO is indium tin oxide, SA is self-assembled, P3HT is poly(3-hexylthiophene), and PCBM is [6,6]-phenyl-C(61)-butyric acid methyl ester] with this self-assembled PCB (SA-PCBO) modifier showed an impressive power conversion efficiency (PCE) of 4.1%, which outperforms the reference device A (PCE = 3.6%) without this monolayer [ITO/TiO(x)/P3HT:PCBM (1:1 w/w)/MoO(3)/Ag]. This SA-PCBO modifier exerts multipositive effects on the interface, including improvement of exciton dissociation efficiency, reduction of charge recombination, decrease of the interface contact resistance, and passivation of the surface electron traps at the interface of TiO(x). Furthermore, PCBOD, containing two oxetane groups, is capable of self-assembling on the TiO(x) surface and simultaneously undergoing cross-linking, generating a dense, robust, and pinhole-free multimolecular interlayer to further strengthen the interface characteristics. Device C [ITO/TiO(x)/C-PCBOD/P3HT:PCBM(1:1, in wt%)/MoO(3)/Ag] incorporating this cross-linked PCBOD (C-PCBOD) interlayer delivered the highest PCE of 4.5% which represents 26% enhancement over device A. This simple and easy strategy smartly integrates the advantages of self-assembly and cross-linking in a single fullerene-based molecule, showing promise in producing highly efficient inverted PSCs.
Synthesis and Characterization of Bridged Bithiophene-Based Conjugated Polymers for Photovoltaic Applications: Acceptor Strength and Ternary Blends
(2010-01-26)
Chen, Chiu-Hsiang
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Hsieh, Chao-Hsiang
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Dubosc, Martin
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Cheng, Yen-Ju
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Su, Chain-Shu
Six of three-component donor-acceptor random copolymers P1-P6, symbolized as (thiophene donor)(m)-(thiophene acceptor)(n), were rationally designed and successfully synthesized by the palladium-catalyzed Stille Coupling, The 4H-cyclopenta[2, 1-b:3,4-b']dithiophene (CPDT) unit serves as the donor for P1-P4, while file benzothiadiazole (BT), quinoxaline (QU), dithienoquinoxaline, and thienopyrazine (TP) units are used as the acceptor for P1, P2, P3, and P4, respectively. P5 and P6 are structurally analogous to P1 and P2 except for using the dithieno[3.2-b:2',3'-d]silole (DTS) unit as the donor. Because the band gap lowering ability of the acceptor units in the polymer is in the order TP > BR > QU presumably due to the quinoid form Population in the polymers, the optical band gaps call be well adjusted to be 1.2, 1.6, and 1.8 eV for P4, P1, and P2, respectively. It is found that file two bridged bithiophene units, CPDT and DTS, have similar steric and electronic effects oil the P1 and P5 as well as P2 and P6, respectively, leading to comparable intrinsic properties and device performances. Bulk heterojunction photovoltaic cells based oil ITO/PEDOT:PSS/polymer:PC(71)BM/Ca/Al configuration were fabricated and characterized. Although P4 exhibits the lowest optical band gap, broadest absorption spectrum, and highest mobility, the too low-lying LUMO level hinders the efficient exciton dissociation, resulting in a low PCE of 0.7%. Compared with poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT), random copolymer P1 shows more blue-shifted, broader absorption spectrum, comparable mobility, and a higher PCE of 2.0%. In view of the fact that P1 shows it higher band gap with strong absorption in visible region, while PCPDTBT-has a lower band gap to mainly absorb NIR light, a BHJ device with the active layer containing ternary blend of PCPDTBT/P(1)/PC(71)BM was investigated and achieved an enhanced PCE of 2.5%, which outperforms the devices based on the binary blending systems of PCPDTBT/PC7, BM (PCE = 1.4%) or P1/PC(71) BM (PCE = 2.0%,,) Linder the identical conditions. Such an improvement is ascribed to file complementary absorption and compatible structure of P1 and PCPDTBT polymers.
Synthesis and Electroluminescent Properties of Disubstituted Polyacetylene Derivatives Containing Multi-Fluorophenyl and Cyclohexylphenyl Side Groups
(2009-01-02)
Yang, Sheng-Hsiung
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Huang, Chun-Hao
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Chen, Chiu-Hsiang
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Hsu, Chain-Shu
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應用化學系
A new series of disubstituted polyacetylene derivatives that contain multi-fluorine atoms on the pendent phenyl ring have been synthesized and characterized. The results reveal a greater red-shift in UV-vis absorption and PL emission upon incorporating more fluorine atoms on the pendent phenyl ring. Among them, disubstituted polyacetylene with a difluorophenyl group (PDPA-2F) showed the highest luminescent efficiency. The F device performance can be promoted by blending a hole-transporting material TM-TPD into PDPA-2F as the active layer or by using a light-emitting copolymer in which PDPA-2F was copolymerized with a carbazole group (PDPA-2Fcab). A light-emitting diode of ITO/PEDOT/PDPA-2Fcab/Ca/Al revealed a maximum luminescence of 4230 cd . m(-2) at 14 V and a maximum current efficiency of 3.37 cd . A(-1) at 7 V.
Synthesis, photophysical and photovoltaic properties of a new class of two-dimensional conjugated polymers containing donor-acceptor chromophores as pendant groups
(2013)
Lai, Yu-Ying
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Cheng, Yen-Ju
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Chen, Chiu-Hsiang
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Cheng, Sheng-Wen
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Cao, Fong-Yi
A new design for constructing two-dimensional conjugated copolymers with the D(1)A(D-2) repeating pattern (A: acceptor, D-1: donor 1, D-2: donor 2; molecules enclosed in parentheses are pendant groups.), is proposed. D-1 and A are employed to construct the linear main-conjugated polymer chain and D-2 is situated at the conjugated side chains connected to A. We designed and synthesized a series of D-1-A(D-2)-type copolymers, in which D-1 = diindeno[1,2-b: 2',1'-d]-thiophene (DIDT) or fluorene (F), A(D-2) = bis-[4-(dioctylamino)-phenyl] quinoxaline (DOAQX) or bis-[4-(dioctylamino)-phenyl] thieno[3,4-b]-pyrazine (DOATP), and D-2 = N,N-dioctylanilines. The resultant copolymers, PDIDTDOAQX, PFDOAQX, PDIDTDOATP and PFDOATP, possess at least two strong ICT absorptions, thus resulting in better light harvesting. Their optical and electronic properties were thoroughly investigated experimentally and computationally. Bulk heterojunction photovoltaic cells on the basis of ITO/PEDOT: PSS/polymer: PC71BM/Ca/Al configuration were fabricated and characterized. The photovoltaic performances of the devices incorporating these polymers follow the sequence: PDIDTDOAQX > PFDOAQX > PDIDTDOATP > PFDOATP, which is in good agreement with the magnitude of their hole-mobilities.
Synthesis, Photophysical and Photovoltaic Properties of Conjugated Polymers Containing Fused Donor-Acceptor Dithienopyrrolobenzothiadiazole and Dithienopyrroloquinoxaline Arenes
(2012-03-27)
Cheng, Yen-Ju
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Ho, Yu-Ju
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Chen, Chiu-Hsiang
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Kao, Wei-Shun
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Wu, Cheng-En
We have developed two nitrogen-bridged pentacyclic donor-acceptor dithienopyrrolobenzothiadiazole (DTPBT) and dithienopyrroloquinoxaline (DTPQX) arenes where the two outer electron-rich thiophene moieties are covalently fastened with the central electron-deficient benzothiadiazole and quinoxaline cores by two nitrogen bridges. These rigid and coplanar DTPBT and DTPQX building blocks were copolymerized with fluorene (F), carbazole (C) and cyclopentadithiophene (CPDT) units via Suzuki or Stifle coupling polymerization to afford six new alternating copolymers PFDTPBT, PCDTPBT, PCPDTDTPBT, PFDTPQX, PCDTPQX and PCPDTDTPQX, respectively. The nitrogen bridges not only planarize the structure to induce stronger intermolecular pi-pi interaction but also play an important role in determining the electronic and photophysical properties of the polymers. The device based on PFDTPQX/PC71BM (1:4, w/w) exhibited a open-circuit voltage (V-oc) of 0.72 V, a short-circuit current (J(sc)) of 8.62 mA/cm(2) and a FF of 0.55 leading to a decent power conversion efficiency (PCE) of 3.40% due to the lower-lying HOMO energy level, and the highest hole-mobility of PFDTPQX
Thieno[3,2-b]pyrrolo Donor Fused with Benzothiadiazolo, Benzoselenadiazolo and Quinoxalino Acceptors: Synthesis, Characterization, and Molecular Properties
(2011-10-21)
Cheng, Yen-Ju
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Chen, Chiu-Hsiang
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Ho, Yu-Ju
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Chang, Shu-Wei
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Witek, Henryk A.
Nitrogen-bridged donor acceptor multifused dithienopyrrolobenzothladiazole (DTPBT) and dibenzothiadiazolopyrrolothlophene (DBTPT) were successfully synthesized by intramolecular Cadogan annulation. The electron-deficient benzothiadiazole unit In DTPBT can be converted to benzoselenadiazole and quinoxaline moieties through reduction/cyclization to generate dithienopyrrolobenzoselenadiazole (DTPBSe) and dithienopyrroloquinoxaline (DTPQX), respectively. The nitrogen atoms function as the bridges for covalent planarization to induce intermolecular interaction and intramolecular charge transfer.