The authors reported a charge transfer thin film exhibiting organic electroluminescent (EL)
properties that was made from an organic varnish including an aniline oligomer as a charge transfer
material. Cu-PC is used as a standard charge transfer material in the field of organic EL; it is coated on
a surface as a thin film using a suitable dry process such as a vacuum method because of its low
solubility. There is a need for Cu-PCs having high heat and light resistance for use in wet processes
such as spin-coating, spraying, and ink-jet methods because of the demand in large EL display
manufacture. Cu-PCs presents the disadvantage of lower transmittance in the visible region because of
their strong absorption maxima Q bands.