Louis J. Sorriero

Hole transport in tri-p-tolylamine doped polymers: the role of the polymer dipole moment

Abstract Hole mobilities have been measured in tri-p-tolylamine (TTA) doped polymers with polymer dipole moments that range from near-zero to 1.7 debye. The results are described within the framework of a formalism based on disorder, due to Bassler and coworkers. The formalism is based on the assumption that charge transport occurs by hopping through a manifold of localized states with superimposed energetic and positional disorder. The key parameter of the formalism is σ, the variance of the hopping site energies. The principal observations of this work are: (1) σ increases with increasing intersite distance for all polymers studied, and (2) σ increases with increasing dipole moment of the polymer. The interpretation of the results leads to the conclusion that for weakly polar dopant molecules, a major contribution to the width of the distribution of hopping site energies is the component due to van der Waals forces. For TTA doped poly(styrene)s, the van der Waals component is estimated as between 0.074 and 0.116 eV, increasing with incresing intersite distance or decreasing TTA concentration.

Applications and new developments of the direct exponential curve resolution algorithm (DECRA). Examples of spectra and magnetic resonance images

Recently, a new multivariate analysis tool was developed to resolve mixture data sets, where the contributions (‘concentrations’) have an exponential profile. The new approach is called DECRA (direct exponential curve resolution algorithm). DECRA is based on the generalized rank annihilation method (GRAM). Examples will be given of resolving nuclear magnetic resonance spectra resulting from a diffusion experiment, spectra in the ultraviolet/visible region of a reaction and magnetic resonance images of the human brain. Copyright

High-Mobility Doped Polymers

Hole mobilities have been measured in 1,1-bis(di-4-tolylaminophenyl)cyclohexane (TAPC) doped in a series of segmented thermoplastic polymers. For TAPC concentrations of 25 wt%, the mobilities are as high as 3×10-3 cm2/Vs. To our knowledge, these values are a factor of 100 higher than any hole mobilities described in the literature for this dopant concentration.

Hole Transport in 1,1-Bis(di-4-tolylaminophenyl)cyclohexane-Doped Copolymers

Hole mobilities have been measured in 1,1-bis(di-4-tolylaminophenyl)cyclohexane (TAPC) doped in a series of segmented thermoplastic copolymers. The mobilities are unexpectedly high, exceeding values obtained with TAPC-doped poly(styrene) by as much as 2 orders of magnitude. The results show that the enhancement in mobilities is due to an increase in the prefactor mobilities. The activation energies are not affected by changes in the polymer host. The enhancement is attributed to the preferential segregation of the TAPC into the styrene phase of the copolymers.