Nanocrystalline electronic junctions

Nanocrystalline semiconductor films are constituted, by a network of mesoscopic oxide or chalcogenide particles, which are interconnected to allow electronic conduction to take place. The pores between the particles are filled, with a semiconducting or a conducting medium, such as a p-type semiconductor, a hole transmitter, or an electrolyte, forming a junction of extremely large contact area. In this fashion, the negatively and positively charged contact of the electric cell become interdigitated on a length scale as minute as a few nanometers, leading to a whole series of intriguing properties, for which a realm of important applications are discussed. The unique optical and electronic features of such junctions may be exploited to realize opto-electronic devices, exhibiting outstanding performance, including super-capacitors, sensors, photovoltaic injection cells, luminescent diodes, and electrochromic displays, as well as photochromic switches and intercalation batteries. Current research activities of this new and rapidly moving field are also discussed in the chapter. © 1997, Elsevier Science & Technology