Photophysics of organic emissive semiconductors under hydrostatic pressure

Abstract The impact of hydrostatic pressure on conjugated organic semiconductors has been studied using optical spectroscopic techniques. This work focuses on three blue emitters with distinct backbone conformations: planar methylated ladder‐type poly para phenylene, semi‐planar polyfluorene (PF), and nonplanar para hexaphenyl. The effect of pressure on the backbone emission and defect related emission allows an understanding of the localized, delocalized electronic states and energy transfer mechanisms of the singlet excitons into defect states. The Raman spectrum of the organic emitters under pressure demonstrates changes in the backbone conformation and mesomorphic phases. The Raman peaks in PF exhibit asymmetric Fano‐type line shapes beyond 40 kbar, where the defect emission is enhanced. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)