Donor-acceptor superlattice

TCNQ derivatives incorporated in a donor-acceptor superlattice also been used for studies on photoinduced electron transfer [186-190],... 

Cumulative photovoltage in asymmetrical donor—acceptor organic superlattices... 

In this section, following (29), we discuss the electrooptical properties of an asymmetric stack of organic donor-acceptor (D-A) interfaces. As we mentioned, the technological progress in molecular organic beam deposition is very fast and there is little doubt that a variety of such systems will be synthesized in the near future. With this in mind, we discuss the properties of a superlattice of... 

Mucic and co-workers [15] and Alivisatos et al. [16] successfully constructed supramolecular self-assemblies of QDs and oligonucleonucleotides by precise molecular recognition of nucleotides and Watson-Crick base-pairing interactions, respectively. These methods can precisely control the coupling distance of two quantum dots of a species. Similarly, artificial molecules of homostructures may carry out the coupling of quantum dots of heterostructures to form donor-acceptor assemblies, even 2-D or 3-D QD superlattices. 

The major attention is given to the conqjensated GaAs superlattices with the layer thickness of 40 nm and concentration of donors and acceptors of 10 cm. The superlattice named No. 4i contains i-layers n-i-p-I stracture) and No. 4 means no i-layers n-p-n-p stmcture). Both structures belong to the long-period doping superlattices and their photoluminescence properties were measured in a wide temperature range. Pronounced effects of a-irradiation were observed [7]. 

One can experimentally derive the degree of charge transfer (Z) [73-75] between donor and acceptor from the location of the superlattice X-ray spots (diffuse or sharp). Let the superlattice periodicity due to 2kp or 4kp scattering be A., and let d be the regular (or high-temperature static) lattice spacing. Then it can be shown that ... 

Semi-amphiphilic molecules are used to develop conductive LB films. In this case, unsubstituted active molecules are attached to amphiphiles through Coulomb interactions (Figure 14.5). This method is employed for the construction of the LB films of charge-transfer complexes and ion radical salts. In the former case the amphiphile should be electrically active and in the latter inert molecules can be used. By using amphiphilic donor and acceptor, a superlattice of alternate layers with non-centrosymmetric structure is obtained (Figure 14.6). 

There are three different ways to fabricate conductive LB films of charge-transfer complexes. The first method is to use semi-amphiphilic molecules, i.e. a CT complex of an amphiphilic donor or acceptor with an unsubstituted counterpart. We can use a mixture of amphiphilic donor and acceptor as a film-forming material (mixed LB film). This is the second method. The third method utilises an alternate layer structure of donor and acceptor (LB superlattice). 

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