The Luminescent Process in Organic Light Emitting Devices

摘要

Understanding the electroluminescent (EL) process in organic light emitting devices is very important for the rational design of optimized chromophores for use in organic LEDs. By comparing solution and solid state fluorescence spectra, it has been shown that molecularly localized or Frenkel excitons are responsible for the EL output. This makes theoretical modeling of the emission process fairly straightforward, since isolated molecules can be used in the theoretical calculations. We have carried out an extensive molecular orbital study of several different molecules used in vacuum deposited LEDs. The calculations were carried out using a semiempirical molecular orbital program (ZINDO) which is designed to give allowed transition energies and orbital compositions for metal complexes. In these calculations the ground state structures are taken from crystallographic data.