Triarylamine polymer

Fewer examples are reported for organic electrode reactions some alkyl halides were catalytically reduced at electrodes coated with tetrakis-p-aminophenylporphy-rin carboxylate ions are oxidized at a triarylamine polymer and Os(bipy)3 in a Nafion film catalytically oxidizes ascorbic acid Frequently, modified electrodes fail to give catalytic currents for catalyst substrate combinations that do work in the homogeneous case even when good permeability of the film is proven... 

Since the ionization potential of 238 matches closely the work function of PEDOT (5.1-5.3 eV) [335], the hole injection is dramatically improved. Accordingly, the device ITO/PEDOT/237 238(7 3)/Al has a significantly improved EL efficiency, tjel= 1.5cd/A, two orders of magnitude higher than that of single-layer PLED with 237, six times higher than that of bilayer PLED with triarylamine polymer HTL, and almost twice as high as that of PF blends with low molecular triphenylamine HT materials (in device with Ca electrode) [321]. 

Aromatic amines are frequently used as xerographic materials and incorporated in OLEDs,[139] while reports of their use as the semiconductor material in OFETs are few. Only very recently triarylamine polymers have been used in OFETs.[140,141] Star-shaped molecules with triphenylamine core and carbazole (20a, 20c-20d) or fluorene (20b) side groups have all been characterized in OFETs (Figure 3.1.7).[142] Devices containing these materials were fabricated using a drop casting technique and showed mobilities on the order of 10 cm V s with good stability under ambient conditions. 

An alternative approach to the synthesis of triarylamine polymers is the reaction of a dihalobenzene with a primary arylamine. In this case, the catalyst must be able to form both diarylamines from anilines and triarylamines from the diarylamine product in nearly quantitative yields. The discussion of catalysts above shows that complexes of P(t-Bu)3 effectively catalyze both these transformations. Kanbara and co-workers have used this... 

Chrotnophoric unit containing triarylamine polymers reported by Kanbara... 

Triarylamine polymers can be rapidly assembled by microwave-assisted amina-tion of aryldibromides (Horie et al, 2008). A series of polymers was formed with backbones containing 4,4 -biphenyl, 2.9-fluorene and 3,6-carbazole repeating units. These polymers have been used to fabricate organic field-effect transistors. The devices show very stable operation under ambient conditions and p-type mobilities up to 2.3 X 10 cm s close to the highest mobility reported to date for this class of amorphous semiconductors. 

Ma and coworkers [154] synthesized a bipolar luminescent PPV-based polymer 111, which contained both donor triarylamine and acceptor oxadiazole moieties in the backbone. A device fabricated with this polymer (ITO/PEDOT/111/CsF/Al) showed a maximum brightness of 3600 cd/m2 and a maximum luminescent efficiency of 0.65 cd/A (< el = 0.3%), about 15 times brighter and more efficient than the device of the same configuration with a nonoxadiazole polymer 112. 

Copolymerization of fluorene with triarylamine compounds was shown to increase the hole-transport properties of the polymers. Several copolymers of triarylamine and fluorene (246-250) synthesized by Suzuki coupling were reported by Bradley et al. [347,348], The hole s... 

Dow Chemicals group and coworkers [276,350] synthesized similar triarylamine-fluorene copolymers 251 and 252, possessing carboxylic acid substituents, via hydrolysis of the corresponding ethyl ester polymers, prepared by Suzuki polymerization. Due to the very polar substituents, the copolymers 251 and 252 are only soluble in polar solvents such as DMF but not in aromatic hydrocarbons as toluene or xylene, which allowed simple fabrication of multilayer PLEDs by solution processes (Chart 2.65). 

Fang and Yamamoto [351] reported on postpolymerization functionalization of triarylamine-fluorene copolymer 253, resulting in copolymers 254a,b with stilbene pendant groups. Whereas in the solid-state absorption and PL maxima of both polymers are essentially the same, PL in solution is strongly influenced by solvent (from 433 nm in toluene to 466 nm in jY-methylpyrrolidone). Copolymer 254a showed d>PL in the solid state of 51%, comparable to that of poly(9,9-dialkylfluorenes) (Chart 2.66). 

S. Liu, X. Jiang, H. Ma, M.S. Liu, and A.K.-Y. Jen, Triarylamine-containing poly(perfluorocy-clobutane) as hole-transporting materials for polymer light-emitting diodes, Macromolecules, 33 3514-3517, 2000. 

Grubbs group reported a series of cross-linkable triarylamine-containing poly(norbor-nenes) (51) and investigated them as the HTMs in a bilayer OLED (Scheme 3.19) [94]. However, cross-linking was found to decrease the device performance due to the low Ts of the polymers and the poor film quality after UV irradiation. 

Polymeric materials invented by CDT are conjugated homo- or copolymers. Examples are poly(arylenevinylene)s, [ArCRy CR2L] , polymers with triarylamine and triazine groups (Figure 11.17), and fused thiophenes as structural repeating units (Figure 11.18). 

FIGURE 11.17 Polymer with triazine and triarylamine moiety. 

Fig. 3 TFB F8BT structures (slightly tilted forward) showing two different orientations of the polymer constituents. In each, the FBT (top chain) consists of 3 fluorene (F) units and 3 benzothiadiazole (BT) units while the TFB (bottom chain) consists of 3 F units and 2 triarylamine (TB) units. These co-monomer units are labeled with indices. The eclipsed orientation (panel a) has the middle F units (F12 and F22) of both chains 7r-stacked while the staggered orientation (panel b) has the middle BT of FBT (BT2) and the middle F of TFB (F22) 7r-stacked, see Eqs. (l)-(2). Reprinted with permission from Ref. [41]. Copyright 2007, American Institute of Physics.

Cyclic voltammetry revealed that the N-atoms of 86a, 88a and 91a are oxidized at lower potentials than the trivalent P atoms. Comparison of these data with those observed with model compounds shows a very weak electronic delocalization via the P centers for copolymers 86a and 91a. In contrast, the low first oxidation potential observed for 88a (Table 4.5) is assumed to result from an electronic communication between the N moieties through the connecting P centers [59b]. The equivalence of the oxidation potentials for the oxidized polymers (Table 4.5) suggests the presence of electronically isolated triarylamine fragments in these derivatives. Note that the involvement of the P lone pair in jt-delocalization... 

Arylamines are commonplace, as components of molecules with medicinally or electronically important, catalytic active, or structurally interesting properties. An aryl-nitrogen linkage is included in nitrogen heterocycles such as indoles [4,5] and benzopyrazoles, conjugated polymers such as polyanilines [6-12], and readily oxidized triarylamines used in electronic applications such as 4,4 -bis(3-methylphe-... 

---