Oligo doping

Two polymers with hydrophilic oligo(ethylene oxide) side chains, 430 and 431, have been synthesized (Scheme 2.69) and studied in LECs [512]. Under applied bias, p-doping of the EL polymer took place at the anode, whereas at the opposite electrode the cathode material was reduced, although the reported Tel was relatively low LUO 2%). 

T. Johansson, W. Mammo, M.R. Andersson, and O. Inganas, Light-emitting electrochemical cells from oligo(ethylene oxidej-substituted polythiophenes evidence for in situ doping, Chem. Mater., 11 3133-3139, 1999. 

More examples include the use of Ir(III) complexes in dendrimers [136] and as pendants in oligo- or polymeric lluorene (or carbazole), in part already discussed in Sect. 3.4 [76,137,138]. Both cases illustrate viable methods to solve the problem of phase separation in electroluminescent polymers doped with Ir(III) complexes and are not treated here in detail. 

Bulk semiconductor nanostructured networks of CdS have been prepared in L and Hi phases [33,34]. The L phase was formed by a polyol amphiphile shown in Fig. 6. This LLC phase was doped with Cd2+ ions and then CdS was precipitated by diffusion of H2S into the gel. This nanocomposite was found to incorporate the amphiphile and metal in alternating layers (Fig. 6), closely resembling the structure of biominerals (e.g., mother of pearl). Similarly, Hi phases were prepared from an oligo(ethylene oxide) oleyl ether amphiphile (Fig. 7) mixed with a solution of Cd2+. Again, H2S was added to precipitate CdS and the resulting composite preserved the hexagonal symmetry (Fig. 7). 

The conducting and physical properties can be modified by the use of 3-/4-substituents, or A-substituents in the case of pyrrole. The counter-ions can be incorporated into a side-chain (self-doping), as in the polymer of 3-(thien-3-yl)propanesulfonic acid. Oligo(thiophenes) are also useful in these applications and have been specifically synthesised up to 27 units long by palladium(0)-catalysed couplings or via the diacetylene synthesis (17.12.1.1). ... 

Borodin O et al (2006) Li Transport in lithium sulfonylunide-oligo(ethylene oxide) ionic liquids and oligo(ethylene oxide) doped with LiTFSI. J Phys Chem B 110 24266... 

Table 15.12 Conductivity of poly[(disilanylene)oligo-phenylenes], 34 after doping with iodine vapor [52]...

Table 15.16 Conductivity of poly[(disilanylene)-oligo-thienylenes] 52a-d doped with I2 and FeCl3[74]...

The relative stabilities of the oxidized oligo(thiophene)s and PTs depend on the oxidation state (i.e. the doping level) [177, 541]. The dependence is weakest for FeCla-doped PAT above 10 Scm Below that value the dedoping rate decreases with decreasing electrical conductivity, as is the case for organic acid anions. For the dopant I2 and the dopant anion PFg the decay rate is proportional to the electrical conductivity [189]. The deterioration of the electrical conductivity with time depending on the doping level is also found for PAT with n = 12 [542]. PBT in the neutral (dedoped) form is stable up to 300 °C and... 

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