Prolonged storage ( approximately 2 years) or gentle heating (50-80 degrees C) of crystalline 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) affords a highly conducting, bromine-doped poly(3,4-ethylenedioxythiophene) (PEDOT), as confirmed by solid-state NMR, FTIR, CV, and vis-NIR spectroscopies. The novel solid-state polymerization (SSP) does not occur for 2,5-dichloro-3,4-ethylenedioxythiophene (DCEDOT), and requires a much higher temperature (>130 degrees C) for 2,5-diiodo-3,4-ethylenedioxythiophene (DIEDOT). X-ray structural analysis of the above dihalothiophenes reveals short Hal.Hal distances between adjacent molecules in DBEDOT and DIEDOT, but not in DCEDOT. The polymerization may also occur in the melt but is significantly slower and leads to poorly conductive material. Detailed studies of the reaction were performed using ESR, DSC, microscopy, and gravimetric analyses. SSP starts on crystal defect sites; it is exothermic by 14 kcal/mol and requires activation energy of approximately 26 kcal/mol (for DBEDOT). The temperature dependence of the conductivity of SSP-PEDOT (sigma(rt) = 20-80 S/cm) reveals a slight thermal activation. It can be further increased by a factor of 2 by doping with iodine. Using this approach, thin films of PEDOT with conductivity as high as 20 S/cm were fabricated on insulating flexible plastic surfaces.

No abstract

Articles you may be interested in Effects of end-of-range dislocation loops on transient enhanced diffusion of indium implanted in siliconA study of end-of-range ͑EOR͒ dislocation loops in silicon implanted with 50 keV 10 16 Si/cm 2 was carried out by using transmission electron microscopy. Two kinds of post-implantation anneals were performed, furnace anneals at 850°C and rapid thermal anneals at 1000°C. We observed the ripening for two types of EOR dislocation loops. They were faulted Frank dislocation loops and perfect prismatic dislocation loops. By separating their size distribution profiles, we found that their distribution profiles are different from that of conventional Ostwald ripening for precipitates. A long tail distribution profile was formed for perfect prismatic dislocation loops. We analyzed the distribution profiles and found that the size distribution profile of faulted Frank dislocation loops could be well fitted by a normal Gaussian probability function and that of perfect prismatic dislocation loops by a log-normal Gaussian probability function. Measurement of the total number of interstitials within both types of loops shows that the ripening of EOR dislocation loops is conservative. Knowing the size-distribution profiles of the EOR dislocation loops, it was possible to perform an analysis of the ripening behavior of the two types of dislocation loops.

Articles you may be interested inEffect of 0.5 wt% Cu addition in Sn-3.5%Ag solder on the dissolution rate of Cu metallization J. Appl. Phys. 94, 7904 (2003); 10.1063/1.1628387 Effect of reaction time and P content on mechanical strength of the interface formed between eutectic Sn-Ag solder and Au/electroless Ni(P)/Cu bond pad

No abstract