Synthesis and Characterization of a New Series of Blue Fluorescent 2,6Linked 9,10-Diphenylanthrylenephenylene Copolymers and Their Application for Polymer Light-Emitting Diodes (original) (raw)
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Journal of Materials Chemistry, 2012
Two benzo[1,2-b:4,5-b 0 ]dithiophene (BDT) derivatives with conjugated substituents, triisopropylsilylethynyl (TIPS) and 4-octylphenylethynyl groups, were synthesized as donor units (D) and copolymerized with two acceptor units (A), 4,7-bis(4-octylthiophen-2-yl)-2,1,3-benzothiadiazole (BT) and 4,4 0 -diundecyl-2,2 0 -bithiazole (BTZ), respectively, using Stille coupling reaction to afford four new copolymers, PTBDT-BT, PTBDT-BTZ, POPEBDT-BT, POPEBDT-BTZ. All polymers exhibited highest occupied molecular orbital (HOMO) energy levels that were deeper than À5.4 eV due to the conjugated substituents. Small band gaps were successfully achieved for PTBDT-BT (1.67 eV) and POPEBDT-BT (1.67 eV) and were attributable to the strong intramolecular charge transfer within the D-A alternating structure. The resultant photovoltaic performances showed high open-circuit voltages (V oc ) ranging from 0.73 V to 0.92 V, whereas the power conversion efficiencies (PCEs) depended strongly on the blend morphologies. The polymer solar cell based on the blend of PTBDT-BT and PC 71 BM gave the best photovoltaic performance among the series, with a high V oc of 0.81 V and a PCE of 4.61%.
Polymer Chemistry, 2014
A new benzo[1,2-b:4,5-b']dithiophene (BDT) building block with 4,8-disubstitution using 2-(2ethylhexyl)-3-hexylthieno[3,2-b]thiophene as the substituent has been designed and synthesized. The new building block has been copolymerized with benzothiadiazole (BT) and 5,6-difluorobenzothiadiazole (fBT) by Suzuki and Stille coupling polymerization to synthesize donor-acceptor conjugated polymers. The optical and electrochemical properties of the synthesized copolymers were studied. Bulk heterojunction solar cells were fabricated using the donor-acceptor copolymers in conjunction with PC 71 BM and exhibited up to 4.20% power conversion efficiency. 65 the delocalization of holes over the side chain, thus lowering
Synthetic Metals, 2009
Two alternating conjugated copolymers TTP and TTT were synthesized by Heck coupling of 2,3-bis-(5-bromothiophene-2-yl)acrylonitrile with 1,4-dihexyloxy-2,5-divinylbenzene and 3-hexyl-2,5divinylthiophene, respectively. The absorption spectra of the copolymers in THF solution showed three maxima around 270, 370 and 460 nm with optical band gaps of 2.30-2.34 eV. The electrochemically estimated band gaps of copolymers were 2.04-2.10 eV. The thin film absorption spectra were broad and extended about from 250 to 600 nm with a long wavelength maximum near 470 nm. The copolymers emitted yellow-orange light with maximum at 528-551 nm in THF solution and 567-610 nm in thin film. TTP showed the most red shifted emission maximum between the copolymers. The performance of the photovoltaic cells which were fabricated using blends of the copolymers with 6,6-phenyl C61-butyric acid methyl ester (PCBM) (1:1 and 1:4, w/w) as well as pure copolymers was investigated.
Synthetic Metals, 2013
Full donor-type conjugated polymers containing benzodithiophene and thiophene derivative units were synthesized as electron donors for organic photovoltaic devices. The alkoxy-substituted benzo[1,2b:4,5-b ]dithiophene (BDT) monomer, 2,6-bis(trimethyltin)-4,8-di(2-ethylhexyloxyl)benzo[1,2-b:4,5b ]dithiophene, was polymerized with 2,5-dibromothiophene through a Pd(0)-catalyzed Stille coupling reaction. To enhance the interchain interactions between polymers chains, an alkylselenophenesubstituted BDT derivative was newly synthesized, and copolymerized with the same counter monomer parts. The two newly synthesized polymers were characterized for use in organic photovoltaic devices as electron donors. Measured optical band gap energies of the polymers were 2.10 and 1.96 eV, depending on polymer structure. Field-effect transistors were fabricated using the polymers to measure their hole mobilities, which ranged from 10 −3 to 10 −5 cm 2 V −1 s −1 depending on the polymer structure. Bulk heterojunction organic photovoltaic cells were fabricated using conjugated polymers as electron donors and a [6,6]-phenyl C 71-butyric acid methyl ester (PC 71 BM) as an electron acceptor. One fabricated device showed a power conversion efficiency of 2.73%, an open-circuit voltage of 0.72 V, a short-circuit current of 7.73 mA cm −2 , and a fill factor of 0.46, under air mass (AM) 1.5 global (1.5 G) illumination conditions (100 mW cm −2).
Efficient deep blue fluorescent polymer light-emitting diodes (PLEDs)
Journal of Materials Chemistry C, 2014
A new series of deep blue/blue emitting co-polymers are reported. Poly(9,9-dihexylfluorene-3,6-diyl and 2,7-diyl-co-2,8-dihexyldibenzothiophene-S,S-dioxide-3,7-diyl) derivatives p(F-S) of varying composition have been synthesised. The effects of two different S derivatives with dialkoxy sidechains, the F : S monomer feed ratio, and meta versus para conjugation with respect to the F units have all been investigated in terms of photophysics and polymer light-emitting diode (PLED) device performance in the architecture ITO/PEDOT:PSS/polymer/TPBi/LiF/Al. The meta polymers poly(9,9-dihexylfluorene-3,6diyl-co-2,8-di(O-methylenecyclohexyl)dibenzothiophene-S,S-dioxide-3,7-diyl) p(F m -S OCy ) in three different co-monomer ratios, P1-3, give deep blue electroluminescence peaking at 415 nm, with the ratio of 70 : 30 p(F m : S OCy ) producing a maximum external quantum efficiency (EQE) h ext, max 2.7%, whilst the ratio of 85 : 15 gave the highest maximum brightness L max of 81 cd m À2 , with CIE coordinates (0.17, 0.12) The analogous para series poly(9,9-dihexylfluorene-2,7-diyl-co-2,8-di(O-methylenecyclohexyl)dibenzothiophene-S,S-dioxide-3,7-diyl) p(F p -S OCy ) and poly(9,9-dihexylfluorene-2,7-diylco-2,8-dihexyloxydibenzothiophene-S,S-dioxide-3,7-diyl) p(F p -S O6 ) in two different ratios, P4-7, produced blue emission peaking at ca. 450 nm. The ratio of 70 : 30 F : S units consistently gave better devices than the corresponding 50 : 50 co-polymers. It was also observed that co-polymers incorporating the bulkier S OCy derivatives gave more efficient and brighter devices, with polymer P5 attaining a remarkable h ext, max 3.2%, 4.4 cd A À1 , 3.4 lm W À1 and maximum brightness 2500 cd m À2 with CIE (0.16, 0.18).
Journal of Applied Polymer Science, 2009
Two new soluble alternating phenylenevinylene copolymers S and L which contained dithienbenzothiadiazole moieties were synthesized by Heck coupling. The repeating unit of L was longer than that of S and contained two additional phenylene rings and two cyano-vinylene bonds. Both copolymers were stable up to about 350 C and afforded char yield of 52-66% at 800 C in N 2 . Their absorption spectra were broad and extended up to about 600 nm with a longer wavelength maximum at 447-502 nm and optical band gap of $ 2.0 eV. These copolymers emitted yellow light in solution with PL max-imum at 551-580 nm and orange-red light in thin film with PL maximum at 588-661 nm. The emission maximum of L was considerably red-shifted relative to S. Photovoltaic cells based on S (or L) as donor and [6,6]phenyl C61-butyric acid methyl ester as acceptor were investigated. V
Journal of Polymer Science Part A: Polymer Chemistry, 2015
The synthesis and characterization of two low band gap copolymers (P1 and P2) incorporating benzo[1,2-b:4,5b']dithiophene unit substituted with octylsulfanylthienyl groups (OSBT) are here reported. These materials, designed to be employed in polymer solar cells (PSCs), were obtained from alternating OSBT and bithiophene (P1) or thienothiophene (P2) units. Their structural electrochemical and photophysical properties were investigated. They are thermally stable and soluble in organic solvents from which they easily form films. They also form p-stacks in solution, in film and display a moderate solvatochromism. These polymers were tested with [70]PCBM in bulk-heterojunction (BHJ) PSCs where they act as donor materials and [70]PCBM is the electron acceptor. The best device, obtained using a 1:3 weight ratio for the P1:[70]PCBM blend, shows a PCE around 1.5%. A broad response from 350 to 700 nm is also observed in the external quantum efficiency (EQE) curves, wider for P1 with respect to P2. V