Effects of plasma-induced high-energy particles on the damage of organic thin films

Abstract

We have investigated the effect of plasma-induced damages on the electron transport layers in organic light-emitting devices. Tris(8-hydroxyquinolinato) aluminum, tris(2,4,6-trimethyl-3-(pyridine-3yl)phenyl) borane, and 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ) layers were used for studying plasma-induced degradation of electron transport materials. The thicknesses, photoluminescence spectra and the current-voltage curves of organic electron transport materials were measured after exposing to Ar plasma. The high-energy species in plasma induce the sputtering of organic layers, quenching of emission sites, and the creation of defect sites in organic layers. The plasma-induced damage was strongly dependent on the glass transition temperature, exhibiting the most serious degradation in the TAZ with low glass transition temperature.