Electrochemically doped polymers

Electrochemical doping. Polymers can be doped electronically in an electrochemical cell, such as by immersing the material as an electrode in an organic electrolyte solution (LiC104 in tetrahydrofuran or propylene carbonate, with lithium as a counter electrode) or in aqueous electrolytes (PbS04/Pb02 in sulfuric acid solutions, with lead as a counter electrode). 

The electrochemically doped polymers were identified as partially oxidized radical cation salts (ferrocenium ion salt in poly(vinylferrocene)) containing CIO4 as a dopant. The infrared absorption spectra and cyclic vol-... 

The electrochemically doped polymers containing pendant TT-electron systems function as electrode materials for rechargeable batteries, photoactive materials for photovoltaic devices, and electrochromic materials. 

The cell showed rectification behavior in the dark. This result and the results obtained by photoirradiation through aluminum and through gold or ITO indicate that a Schottky barrier is formed at the interface between aluminum and the electrochemically doped polymer, which acts as a p-type semiconductor. 

Electrogenerated conducting polymer films incorporate ions from the electrolyte medium for charge compensation (182). Electrochemical cycling in an electrolyte solution results in sequential doping and undoping of the polymer film. In the case of a -doped polymer, oxidation of the film results in the... 

The other way to produce EL devices is based on a pin junction [47]. A pin junction with conjugated polymers was realized by electrochemical doping of the... 

One idea to realize a pin junction with conjugated polymers is to create it in situ by electrochemical doping. By using the conjugated polymer in a solid slate electrochemical cell, the production of bipolar light-emitting pin junction devices can be realized [69, 70]. 

Table 5.3 Examples of electronically conducting polymers, y is the level of electrochemical doping and k is the maximum electrical conductivity. Except for poly acetylene and polyparaphenylene, only p-doping is considered... 

It is a convenient aspect of electrochemical doping of the polymer that the electrolyte can provide the counter ion, although a similar result can be achieved via chemical doping under certain circumstances, e.g., Using a radical ion containing species such as sodium naphthalide, Na+ npthT, i.e.,... 

The speed of p- and n-type doping and that of p-n junction formation depend on the ionic conductivity of the solid electrolyte. Because of the generally nonpolar characteristics of luminescent polymers like PPV, and the polar characteristics of solid electrolytes, the two components within the electroactive layer will phase separate. Thus, the speed of the electrochemical doping and the local densities of electrochemically generated p- and n-type carriers will depend on the diffusion of the counterions from the electrolyte into the luminescent semiconducting polymer. As a result, the response time and the characteristic performance of the LEC device will highly depend on the ionic conductivity of the solid electrolyte and the morphology and microstructure of the composite. 

On one hand, the ionic conductor was unique in creating dynamic junction in LEC. On the other hand, the slow ionic motion and irreversibly electrochemical doping under high biasing field were two of the challenges for polymer LECs to be used in practical applications. More recent works have been focusing on the following directions ... 

It has been shown that the chemical and electrochemical doping of polymers may be described as a redox reaction which involves the... 

---