Browsing by Author "Hsieh, Chao-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%.
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
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Hsieh, Chao-Hsiang
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He, Youjun
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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
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Hsieh, Chao-Hsiang
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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%.
Donor-acceptor polymers based on multi-fused heptacyclic structures: synthesis, characterization and photovoltaic applications
(2010)
Wu, Jhong-Sian
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Cheng, Yen-Ju
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Dubosc, Martin
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Hsieh, Chao-Hsiang
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Chang, Chin-Yen
We report here two novel 2,7-fluorene- and 2,7-carbazole-based conjugated polymers PFDCTBT and PCDCTBT containing ladder-type heptacyclic structures with forced planarity. PCDTBT shows excellent solubility, low band gap and high hole mobility, leading to a power conversion efficiency of 3.7%.
Electroluminescence from a conjugated polymer grafted with CdSe/ZnS: High brightness and improved efficiency
(2006-09-15)
Chen, Kuei-Bai
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Chen, Ming-Hwey
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Yang, Sheng-Hsiung
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Hsieh, Chao-Hsiang
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Hsu, Chain-Shu
A new series of sulfide-substituted poly(1,4-phenylene vinylene) derivatives (S1PPV-S3PPV) with different composition ratios were successfully synthesized,via the Gilch route. The CdSe/ZnS were grafted to the sulfur atoms by ligand exchange reaction. The grafted CdSe/ZnS contents were determined from TGA analysis to be from 4.6 to 37.8%. A new peak at 1151 cm(-1) formed in FT-IR after ligand exchange, which is attributed to the force formation between sulfur and CdSe. The GPC results show that the molecular weights of final polymers became higher after ligand exchange. Thin films of obtained polymers emitted bright green and yellow light with the max emission peak located from 546 to 556 nm. Double-layer LEDs with an ITO/PEDOT/polymer/Ca/Al configuration were fabricated to evaluate the potential use of these polymers. The turn-on voltages of the devices were about 4-5 V As the CdSe/ZnS content increased in grafted polymers, the device performance was significantly enhanced as compared to pristine polymers. In the case of S3PPV, the double-layer device showed a maximum luminance of 6073 cd/m(2) with a current yield of 0.82 cd/A. The maximum luminance and current yield was enhanced to 13,390 cd/m(2) and 2.25 cd/A by grafting CdSe/ZnS onto polymers. (c) 2006 Wiley Periodicals, Inc.
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.
Morphological Stabilization by In Situ Polymerization of Fullerene Derivatives Leading to Efficient, Thermally Stable Organic Photovoltaics
(2011-05-10)
Cheng, Yen-Ju
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Hsieh, Chao-Hsiang
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Li, Pei-Jung
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Hsu, Chain-Shu
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應用化學系
The successful design and synthesis of two styryl-functionalized fullerene derivatives, [6,6]-phenyl-C(61) -butyric acid styryl dendron ester (PCBSD) and [6,6]-phenyl-C 61 -butyric acid styryl ester (PCBS) is presented. The polymerizable PCBS or PCBSD materials are incorporated into a poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) blend to form an active layer of ternary blend. The blending systems are fi rst thermally annealed at 110 C for 10 min to induce optimal morphology, followed by heating at 150 C for 10 min to trigger the in situ polymerization of styrene groups. Through chemical crosslinking of PCBSD, the initial morphology of the blend (P3HT:PCBM:PCBSD = 6:5:1 in weight) can be effectively fi xed and stably preserved. The device based on this blend shows extremely stable device characteristics, delivering an average power conversion effi ciency (PCE) of 3.7% during long-term thermal treatment. By molecular engineering to reduce the insulating portion, PCBS with higher C 60 content (71 wt%) possesses better electron-transport properties than PCBSD (58 wt%). Encouragingly, at a low doping concentration of PCBS in the blend (P3HT:PCBM:PCBS = 6:5:1 in weight), linear-polymerized PCBS can stabilize the morphology against thermal heating. This device exhibits more balanced charge mobility to achieve an average PCE of 3.8% over 25 h heating at 150 degrees C.
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.