Screening by space charge layers and self-localization in conjugated polymers

In devices, strong electric fields do occur at interfaces between the activ e semiconductor and oxides, metals or other semiconductors. They are screen ed by space charge layers (SCL) in the semiconductor. We describe the influ ence of (bi)polaronic states and bipolaron lattice formation on SCL, and we discuss in detail the consequences of such states. A singularity of the ca pacity (maximum at finite T) is caused primarily by one-dimensionality (not by self-localization), and does not lead to a Fermi level pinning as state d before. (C) 2000 Elsevier Science S.A. All rights reserved.