Self-assembled molecular electronics, recent work

RECENT WORK IN SELF-ASSEMBLED MOLECULAR ELECTRONICS... 

Whitesides reviewed the principles of molecular self-assembly over a decade ago,9 including the possibility of using self-assembly to make semiconductor devices. We recently reviewed our extensive work in the field of molecular electronics10 as well as the sub-field of molecular wires,11 both of which include self-assembly as a necessary step in the construction of devices. A review of the physical characteristics of molecular electronics devices has recently appeared,12 along with a review of the genesis of molecular electronics.13 The semiconductor industry has realized that research achievements in the molecule electronics and self-assembly fields could enable the development of methods to bypass existing roadblocks.14... 

The amount of published research in the field of self-assembly has exploded in recent years. A computerized search of the literature using self-assembled as the key phrase returned over 14,000 references (another 29,000 references were returned when the concept of self-assembled was searched). There were 2,619 hits in 2002,2,336 hits in 2001, and 1,971 hits in 2000. The first time the phrase self-assembled appeared was in a review of primitive protein models in 1969.15 Refining the search by including molecular electronics with self-assembled produced 356 hits, with the first reviews appearing in 198116 and 1991.17 Since the thoroughness of any literature search is limited by the search terms used, we have used a variety of methods to find relevant literature through March 2003 for the present work. 

Recent work focuses on non-classical mesogenes which are built up by self-assembly. One example is a family of polymers containing disk-like groups which form no liquid crystalline phase, but ean act as an electron acceptor or donor. Charge transfer complexation with a complementary low molecular mass compound induces nematic or columnar discotic liquid crystalline order [153,154]. Figure 13 demonstrates this with the example of a polyester, bearing electron-rich tetra(alkoxy)tri-phenylene-units in the main chain, mixed with the electron deficient aromatic 2,4,7-trinitro-9-fluorenone (TNF). While the pure polymer shows a non-ordered isotropic melt, a columnar phase appears on addition of TNF. 

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