Browsing by Author "Chiou, De-Yang"

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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
;
Chiou, De-Yang
;
Tsai, Che-En
;
Liang, Wei-Wei
;
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%.
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.
Synthesis and side-chain isomeric effect of 4,9-/5,10-dialkylated-beta-angular-shaped naphthodithiophenes-based donor-acceptor copolymers for polymer solar cells and field-effect transistors
(2017-04-21)
Chiou, De-Yang
;
Cao, Fong-Yi
;
Hsu, Jhih-Yang
;
Tsai, Che-En
;
Lai, Yu-Ying
A systematic methodology is developed to construct the angular-shaped beta-form naphthodithiophene (beta-aNDT) core with regiospecific substitution of two alkyl groups at its 4,9-or 5,10-positions via the base-induced double 6 pi-cyclization of dithienyldieneyne precursors, leading to the two isomeric 4,9-beta-aNDT and 5,10-beta-aNDT monomers. It is found that a more curved geometry of the beta-aNDT units intrinsically increases the solubility and thus the solution-processability of the resultant polymers. Therefore, beta-aNDT units are ideal for polymerization with an acceptor-containing monomer without the need for any solubilizing aliphatic side chains, which are considered the insulating portion that jeopardizes charge transport. Based on this consideration, the 4,9- and 5,10-dialkylated beta-aNDT monomers are polymerized with the non-alkylated DTFBT acceptor to afford two P4,9-beta NDTDTFBT and P5,10-beta NDTDTFBT copolymers for head-to-head comparison of the 4,9-inner/5,10-outer isomeric alkylation effect. It is found that 4,9-beta aNDT adopts a twisted conjugated structure due to the intramolecular steric repulsion between the inner branched side chains and the beta-hydrogens on the thiophene rings. The slightly twisted 4,9-beta-aNDT moiety allows P4,9-beta NDTDTFBT to have higher solubility upon polymerization and thus a higher molecular weight, which eventually induces a higher ordered packing structure in the thin film compared to P5,10-beta NDTDTFBT. As a result, P4,9-beta NDTDTFBT exhibits a higher OFET mobility of 0.18 cm(2) V-1 s(-1), and the P4,9-beta NDTDTFBT: PC71BM-based solar cell device also achieves a higher PCE of 7.23%, which is even better than the corresponding P4,9-alpha NDTDTFBT-based device.
Synthesis, Molecular and Photovoltaic Properties of Donor-Acceptor Conjugated Polymers Incorporating a New Heptacylic Indacenodithieno[3,2-b]thiophene Arene
(2012-12-11)
Chang, Huan-Hsuan
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Tsai, Che-En
;
Lai, Yu-Ying
;
Chiou, De-Yang
;
Hsu, So-Lin
We have developed a new multifused indacenodithieno[3,2-b]thiophene arene (IDTT) unit where the central phenylene is covalently fastened with the two outer thieno[3,2-b]thiophene (TT) rings, forming two cyclopentadiene rings embedded in a heptacyclic structure. This rigid and coplanar IDTT building block was copolymerized with electron-deficient acceptors, 4,7-dibromo-2,1,3-benzothiadiazole (BT), 4,7-dibromo-5,6-difluoro-2,1,3-benzothiadiazole (FBT) and 1,3-dibromo-thieno[3,4-c]pyrrole-4,6-dione (TPD) via Stifle polymerization, respectively. Because the higher content of the thienothiophene moieties in the fully coplanar IDTT structure facilitates pi-electron delocalization, these new polymers show much improved light-harvesting abilities and enhanced charge mobilities compared to PDITTBT copolymer using hexacyclic diindenothieno[3,2-b]thiophene (DITT) as the donor moieties. The device using PIDTTBT:PC71BM (1:4, w/w) exhibited a decent power conversion efficiency (PCE) of 3.8%. Meanwhile, the solar cell using PIDTTFBT:PC71BM (1:4 in wt %) blend exhibited a greater V-oc value of 0.9 V and a larger J(sc) of 10.08 mA/cm(2), improving the PCE to 4.2%. The enhanced V-oc is attributed to the lower-lying of HOMO energy level of PIDTTFBT as a result of fluorine withdrawing effect on the BT unit. A highest PCE of 4.3% was achieved for the device incorporating PIDTTTPD:PC71BM (1:4 in wt %) blend.
Thiophene-Vinylene-Thiophene-Based Donor-Acceptor Copolymers with Acetylene-Inserted Branched Alkyl Side Chains To Achieve High Field-Effect Mobilities
(2018-11-13)
Chiou, De-Yang
;
Su, Yen-Chen
;
Hung, Kai-En
;
Hsu, Jhih-Yang
;
Hsu, Tze-Gang
2-Alkyl((1))alkyl((2))-type aliphatic side chains with a branching point position at the C-2-position (such as 2-ethylhexyl or 2-octayldodecyl) have been widely implanted into numerous donor-acceptor conjugated copolymers for solution processable transistors or organic solar cells. However, the tertiary branching site located at the second carbon inevitably imposes steric hindrance that twists the main-chain coplanarity and attenuates interchain interactions. In this research, we developed a new two-dimensonal thiophene-vinylene-thiophene (TVT) derivative where a carbon-carbon triple bond is inserted between the thiophene unit and the 2-octyldodecyl group. This acetylene-incorporated TVT (aTVT) was copolymerized with 5,10-di(thiophen-2-yl)naphtho[1,2-c:5,6-c']bis-([1,2,5]thiadiazole) (DTNT) and 5,6-difluoro-4,7-di(thiophen-2-yl[benzo][1,2,5]thiadiazole (DTFBT) to form the polymers PaTVT-NT and PaTVT-FBT, respectively. PTVT-FBT, without the triple bond, was also prepared for comparison. The insertion of a linear triple bond moves the tertiary carbon away from the main chain to reduce the steric hindrance, thereby improving the main-chain coplanarity and facilitating the interchain interactions. The acetylene-incorporated copolymers show better thermal stability, red-shifted absorption spectra, stronger intermolecular aggregation, lower-lying electron affinity, and much higher solid-state crystallinity. Due to the linear and coplanar polymeric backbone supported by theoretical calculation, PaTVT-NT exhibits high crystallinity and adopts strong stacking with an edge-on orientation in the thin film evidenced by 2D-GIXRD, leading to a high p-type OFET mobility up to 1.27 cm(2) V-1 s(-1) with an on-off ratio of 9.22 X 10(5). This value represents the highest value among the NT-based polymers. PaTVT-FBT also achieved a high mobility of 0.78 cm(2) which greatly outperforms the corresponding nonacetylene PTVT-FBT counterpart. Most importantly, the preparation of 2-alkyl((1))alkyl((2))-acetylenyl side chain is synthetically feasible, which can be easily applied to create new conjugated polymers for high-performance solution-processable optoelectronics.