Abstract
The relationships between optical properties and assembly states for various nonpolymeric organic dyes have been investigated. Absorption photon energies (ΔEAB) for amorphous films were nearly equal to those for solution samples. However, photoluminescence photon energies (ΔEPL) for amorphous films were smaller than those for solution samples and were nearly equal to those for crystalline samples. Photoluminescence (PL) quantum yields (Q) for amorphous films were generally smaller than those for crystalline and solution samples. PL decay time measurement indicates that nonradiative deactivation processes in amorphous films are faster than those in crystalline and solution samples. The relationship between the optical properties and the molecular structures was investigated using the Pariser-Parr-Pople configuration interaction (PPP-CI) MO method. Many nuclear configurations probably exist for amorphous states and excitation energies are lost in the presence of many rotational and vibrational sites.