Charge transport properties

Triarylamines have been employed in arylene vinylene AB copolymers 38 by Horhold et al. using a Homer polycondensation route of aldehydes and ketones 36 with fois-phosphonate 37 (Scheme 1-12) 164]. Phenylamines have remarkably low redox potentials and their charge transport properties have been investigated extensively [65]. EL devices comprising triarylamines have demonstrated low driving voltages. 

The two forms differ by the way they pack, a direct result being the different tilt angle of their molecular axis (24" and 30" for the low-temperature and high-temperature form, respectively). Another important difference is the fact that the inversion center of the molecule coincides with a center of symmetry of the unit cell in the HT form, whereas it does not in the LT form 84J. Direct consequences of this feature have not yet been identified. It will be of course of great interest to know what would be its influence on charge transport properties. 

The aim of this chapter is to acquaint the reader the physical principles of SE tunneling devices to be used in nanoelectronics. Based on this the charge transport properties of nanocluster assemblies in one, two and three dimensions will be discussed. By means of selected examples it will be demonstrated that ligand-stabilized nanoclusters of noble metals may be suitable building blocks for nanoelectronic devices. 

Recent investigations into the charge-transport properties of M-DNA have indicated highly conducting behavior (2 77). Fluorescence lifetime... 

The discrepancies in the reported conductance data of Au-alkanedithiol-Au junctions attracted our attention, and we decided to carry out an in-depth experimental study of the charge transport properties of Au-a,oo-alkanedithiol-Au molecule junctions in a non-conducting solvent. The combination with quantum chemistry ab initio simulations yielded a detailed view of this archetype of molecular junctions, and helped to resolve the puzzle on the role of microscopic geometries at the contacts and in the molecular conformation. 

DelRio FW, Steffens KL, Jaye C, Fischer DA, Cook RF (2010) Elastic, adhesive, and charge transport properties of a metal-molecule-metal junction the role of molecular orientation, order, and coverage. Langmuir 26 1688-1699... 

Beside the excellent optical properties and suitable HOMO-LUMO energy levels, the PFs possess great charge-transport properties. Time-of-flight (TOF) measurements of PFO showed nondispersive hole transport with a room temperature mobility of holes of fi+ = 4 x 10-4 cm2/(V s) at a field of li 5 x 105 V/cm that is about one order of magnitude higher than that in PPV [259]. The polymer revealed only a weak-field dependence of the mobility, from /r+ = 3 x 1(U4 cm2/(V s) at E= 4 x 104 V/cm to /r+ = 4.2 x 1(V4 cm2/(V s) at E= 8 x 105 V/cm. 

Copolymerization of fluorene with other highly luminescent materials offers a possibility of fine-tuning the emitting and charge-transport properties of PF. Thus Miller and coworkers... 

Spiro-shaped HTMs have been studied extensively (Scheme 3.16) [88,89], The introduction of a spiro center improves the thermal stability of the amorphous state without significantly changing charge-transport properties. Compared with using NPD, TPD HTMs, using 43 in ITO/HTM/Alq3/LiF/Al devices showed very high luminescent efficiency [90]. 

Another direction of investigation is to extend the nanotube array architecture to other metal oxides, most noticeably a-Fc203 and mixed FeTi oxides, to develop materials capable of efficiently responding to the visible light spectrum, while maintaining the outstanding charge transport properties demonstrated by the HO2 nanotube arrays. 

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