Polar organic films: Transport gap, charge-dipole interaction and electroluminescence of tritolylamine (TTA) derivatives

The unusually different photoluminescence (PL) and electroluminescence (EL) of an organic film is related to disordered dipoles and charge-dipole interactions that reduce the transport gap of localized electrons and holes in thermal equilibrium. The assignment of EL as direct emission from ion-pairs in films follows the exciplex interpretation of chemiluminescence (CL) in solutions that contain tritolylamine donors.