Electroluminescence , electrically active polymers

Multiple Heck reactions have also been applied in a number of ways to prepare polymers (Scheme 40). One-dimensionally 7r-conjugated polymers are attractive materials because of their optical and electrical properties resulting from 7r-electron delocalization along their main chains. Among these, poly(p-phenylenevinylene) (PPV) shows high electrical conductivity, large non-linear optical responses, and electroluminescent activity. One approach... 

Of much interest are the electroluminescence properties of conjugated polymers that allow the development of electrically switched light-emitting devices [8.257]. Electric field activated bistable molecules are expected to switch at a critical field strength [8.258]. 

We have shown an extreme enhancement of the exciplex emission in bilayer EL as compared to PL and the appearance of weak exciton EL only through thermal activation from the exciplex at higher temperatures. At low temperatures, the exciton contribution is frozen out completely and only exciplex electroluminescence is seen. This demonstrates unambiguously that the only source of bulk excitons during electrical excitation is endothermic energy transfer from exciplex states that are generated via barrier-free electron-hole capture and confirms the work presented in Section 2.2.1 that was based on room-temperature emission from polymer blend LEDs and time-resolved PL. 

Conducting polymers such as polyacetylene, polypyrrole, polyaniline, polythiophene, etc. have been actively studied for use in various fields due to their interesting properties batteries,46 electrochromic displays,47 materials for supercapacitors,48 corrosion protection,49 protecting layers for static electricity,50 materials for organic electroluminescence displays,51 sensing materials,52 etc. Polypyrrole is reported to be extremely rigid, with a semi-crystalline structure. 

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