Fluorene-bithiophene

Thiem, H. et al.. New fluorene-bithiophene-based trimers as stable materials for OEETs,... 

Some rigid-rod conjugated polymers also exhibit themotropic liquid crystallinity. Therefore, it is possible to align them from the liquid crystalline phase using an alignment layer. Improved mobility using this method was reported for a poly(fluorene bithiophene) copolymer. ... 

A very efficient green-emitting fluorene copolymer 304 was synthesized by Shim and coworkers [390] via Suzuki coupling of dibromothieno[3,2-b]thiophene with dialkylfluorene-diboronic acid [390]. The authors compared the EL properties of this copolymer with PFO homopolymer 196 and PFO-bithiophene copolymer 295. Both the absorption and emission spectra of 304 are red-shifted compared with PFO 196 but slightly blue-shifted compared to bithiophene-based copolymer 295. PLEDs fabricated in the configuration ITO/ PEDOT/304/LiF/Al showed a pure green emission (CIE . v 0.29, r 0.63) close to the... 

As demonstrated in previous sections, the carbazole unit was introduced as a pendant group or as a chain member in major classes of EL polymers such as PPVs (95-105,141,177, 190) and PFs (62, 63, 242-245). A variety of 2,7-carbazole-derived polymers with different conjugated units, such as 2-alkoxy- and 2,5-dialkoxy-l,4-phenylene (549) and l,l -binaphtha-lene-6,6 -diyl (550 [658]), 2,5-pyridine (551), 2,7-fluorene (245 [345,346]), 2,5 -bithiophene (554 [345]), 5,8-quinoxaline (552), quinquethiophene-SjS -dioxide (450 [550]), 2,5-thiophene (553), 2,5-furan (555), and acetylene (556 [659]) were reported by Leclerc and coworkers... 

FIGURE 5.4 Chemical structures of photo- and electroluminescent polymers employed for polarized LEDs poly(2-methoxy-5-(2 -ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV) poly[2,5-dioctyloxy-l, 4-diethynyl-phenylene-a/t-2,5,-bis(2 -ethylhexyloxy)-l,4-phenylene] (EHO-OPPE) poly(p-phenylene), PPP poly(3-(4-octylphenyl)-2,2 -bithiophene), PTOPT poly(p-phenylene vinylene), PPV poly(3-alkylthio-phene vinylene), P3AT Acetoxy-PPY PPV-polyester, poly(9,9-dialkyl fluorene), PF. 

Heeger and coworkers adopted bithiophene as comonomer to copolymerize with fluorene and found that the EL emission can be tuned to emit green light with a peak at 493 nm and a shoulder at 515 nm [57]. The HOMO and LUMO energy levels of copolymer 26 are 5.30 and 2.85 eV, respectively, as estimated... 

In polymers snch as poly(di-octyl-fluorene-co-bithiophene) (E8T2) in which close interchain interactions are weakened by the sp -coordinated carbon atom on... 

A structural combination of fused bithiophene with fluorene (BFTT, 12a) or biphenyl units (BPTT, 12b) has been fabricated (Figure 3.1.4).[102] Thin films of BFTT (12a) and BPTT (12b) showed mobilities of 0.06 cm V- s- and 0.093 cm V s, respectively. The slightly higher mobility of BPTT (12b) may be due to its more planar and straight conformation, which leads to better thin-film packing. 

Not only limited to the PFO polymer, another fluorene-based polymer poly(9,9-dioctylfluorene-a/t-benzothiadiazole) (F8BT) is also able to discrimi-nately wrap SWNTs with larger diameters such as a (15,4) tube." It has been suggested that a stable exciplex between poly[(9,9-dioctyl-fluorenyl-2,7-diyl)-co-(bithiophene)] (F8T2) and SWNTs exists, in which the energy level matching between SWNTs and fluorene-based polymers is responsible for the chirality selectivity. 

L. Zeng, F. Yan, S.K.-H. Wei, S.W. Culligan, S.H. Chen, Synthesis and processing of monodisperse oligo(fluorene-co-bithiophene)s into oriented films by thermal and solvent annealing. Adv. Funct. Mater. 19, 1978-1986 (2009)... 

Huang s group has systematically studied the structure-property relationships of fluorene-thiophene-based conjugated polymers 57-60 [95, 96], In contrast to poly thiophene homopolymers, the regiochemistry of substitution in bithiophene fragments in the studied copolymers shows little effect on the optical bandgap (59 and 60, respectively Eg = 2.49 and 2.58 eV [96] or 2.57 and 2.60 eV [97, 98]) or the emission maxima, but the head-to-head copolymer 60 was significantly more thermally stable. 

H.-C. Lin, H.-H. Sung, C.-M. Tsai, K.-C. Li, Synthesis and characterization of alternating fluorene-based copolymers containing diaryl- and non-substituted bithiophene units. Polymer, 46, 9810-9820 (2005). 

Two important silole-based building blocks are BS [77,78] and TS [79, 80]. The first is also known as silafluorene (SiE, in which a silicon atom replaces the carbon atom in the 9-position of fluorene the second is the silicone-bridged bithiophene (Fig. 17). In both structures the LUMO energy level is lowered by a g -k conjugation within the silole ring. 

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