Improvement in performance of organic light-emitting diodes by adjusting charge-carrier mobility in organic/inorganic hybrid hole transporting layer

The charge-carrier transportation in an organic/inorganic (triphenylamine/SiO2) hybrid film was studied using time-of-flight photocurrent measurement. The hole-mobility increases with triphenylamine concentration and hole transportation in this film corresponds to hopping model. The organic light-emitting diodes (OLEDs) based the organic/inorganic hybrid film as hole-transporting layer were fabricated and electroluminescent characteristics were investigated. The experiments demonstrated that emitting efficiency reached a max value by varying triphenylamine content. A simple model is proposed to explain this character and the theoretical analysis is consistent with the experimental results.