Molecular Electronics

One possible realization of nanoscale electronics has long been a mainstay in science fiction.  It's known as molecular electronics, and it utilizes a host of existing molecules to do the work.  The reason why molecular electronics is so attractive is mainly because a majority of the legwork is already done: a large number of known donor/acceptor molecules have already been synthesized over the last 50 years.  Furthermore, the invention of the STM and AFM in the 1980's have given researchers unprecedented control over the placement of molecules.

Classical thinking dictated that molecular electronics was an impossible endeavor.  Using the basic equation of resistance of a wire, it would seem that a molecular wire would have near-infinite resistance (hence it could not conduct electricity).  But early theorists did not foresee the development of charge transfer molecules developed in the mid-20^th century.  These donor-acceptor systems proved vital in creating a new class of electrically active solid-state materials.  As individual molecules, however, researchers knew that such systems could be used one day for a molecular device.  They just didn't have the right microscopes yet (that would come about 40 years later).

The reason why molecular electronics is so important is because it represents one realization of nanoelectronics using an existing toolbox.  Chemists already know how to tailor donor or acceptor molecules.  They are easy to synthesize and can self-assemble through a variety of functionalization techniques.  Molecules are ideal because they're already in the nanoscale, with larger molecules approaching 100 nm.  In terms of mass production, molecular electronics may be the only way to effective create large quantities of nanoelectronics.

Several research groups have already created functional molecular switches and molecular transistors.  There are plans in the works for new kinds of memory that could store the entire contents of the Internet on a single disk.  Eventually, molecular electronics will create cheap, ultra-fast, and efficient microchips that will power the next generation of computers.

If I were qualified to make a guess, I'd say that work in molecular electronics would probably outpace other bottom-up methods like nanowires and quantum dots.  Though the latter two offer some unique characteristics, they're not as easy to fabricate or control as natural molecules.

Keep your ear to the ground when it comes to molecular electronics.  If there's going to be a major breakthrough in the next few years, I'd definitely expect it to be in this field.