Excited states in conjugated polymers and oligomers probed by photinduced absorption

Summary form only given. Approximately 10 years after their discovery the photoinduced infrared (IR) modes and their electronic companions in the near IR (NIR) and visible (Vis) range are well understood. They tell the observer a lot about the properties of the conjugated polymer under investigation. The dependence of the photoinduced absorption (PIA) on sample temperature is significant for the stabilization mechanism responsible for trapping the photogenerated states that are detected in pseudo steady state measurements. Since these states are seen at the end of a very complicated photophysical process they are discussed in comparison with steady state photoconductivity (long living, mobile charged defects) and ps-PIA-experiments (initial effects of the photoexcitation). We present and discuss the PIA-kinetics (signal vs. chopper period and excitation intensity) which is characteristic for the sample quality. The question of the energetic distribution of photogenerated defects within the gap is also adressed.