Abstract: Since the discovery of metallic conductivity in doped conjugated polymers (such as in doped polyacetylene),semiconducting properties of undoped conugated polymers have been drawn equal attentions. In additonal to the interests in the nonlinear properites of funda-mental excitations in these materials,possibilities of device applocations (such as solar cells and field -effect transistors) have been investigated in the past decade. However,the perfor-mance of polymer devices developed in early times was far from that of commercial devices made with inorganic materials (which was commonly attributed to the low carrier mobility of these materials),that managers and engineers in device industry dropped their initial in-terests gradually on this type of materials in later 1980' s.

Key words: semiconducting polymer devices, photovoltaic cell, optocoupler