Effect of various ions on organic light-emitting diodes obtained by ion-beam-assisted deposition

Abstract.

We present new optoelectronic results upon realization of organic light-emitting diodes obtained in sandwiched structures (ITO/Alq3/Ca/Al) with an original method for organic (Alq3) thin film deposition: the ion-beam-assisted deposition (IBAD). We compare the effects of various ion types: inert ions such as helium and argon, chemically active ions such as iodine (halogens that can act as a P doping in organic materials). We demonstrate that helium ion-beam assistance (E=100 eV,j=100 nA/cm²) realized on the anode side leads to enhanced luminance and quantum efficiency (ten times higher with respect to virgin layer) whereas argon always produces bad effects. Iodine ion beam also induces beneficial effects we attribute to an improvement of the hole injection and to an increase of the P-type conductivity.