Alkoxy-Substituted Poly p-Phenylene Vinylenes

SCHEME 2.11 Synthesis of the first soluble PPV derivative, DH-PPV. (From Askari, S.H., Rughooputh, S.D., and Wudl, F., Synth. Met., 29, E129, 1989.) 

FIGURE 2.2 Operation lifetime of the device ITO/PANI/14/Ca/Al. (From Parker, I.D., Cao, Y., and Yang, C.Y., J. Appl. Phys., 85, 2441, 1999. With permission.) 

Many other monoalkoxy-PPV (e.g., 18a [80]) as well as symmetric (e.g., polymer 18b [81] and 19a [82]) and asymmetric (e.g., polymers 19b-d [83]) dialkoxy-PPVs have been synthesized. Interestingly, the monoalkoxy-PPV 18a demonstrated improved PLQY (55 + 5%) compared to dialkoxy-PPVs, and the authors emphasized a key role of the synthetic conditions determining the photophysical properties of the polymer [80]. 

EL from tetraalkoxy-substituted PPV 20, synthesized by Gilch polymerization, was recently reported [84], A multilayer device ITO/PEDOT/20/PBD/LiF/Al with PBD as an ETL emits green-yellow light with a luminescent efficiency of 0.121m/W, a maximum brightness of 8200 cd/m2, and a turn-on voltage of 5 V. 

The most branched among the alkoxy-PPVs are cholestanoxy-substituted polymers 23 and 24, developed by Wudl and coworkers [81,85-87] (Chart 2.4). The authors suggested that 

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T. Ahn, S. Song, and H. Shim, Highly photoluminescent and blue-green electroluminescent polymers new silyl- and alkoxy-substituted poly(p-phenylene vinylene) related copolymers containing carbazole or fluorene groups, Macromolecules, 33 6764-6771, 2000. 

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