Device performance enhancement in polymer light-emitting diodes by introducing titanium oxide layer

Abstract

One of the serious problems in polymer light-emitting diodes (PLEDs) is the difficulty of electron injection in the current PLEDs device of anode/polymer/cathode geometry. This is particularly true for the case of aluminum (Al) electrode. The work function of Al is too high to match with the Lowest Unoccupied Molecular Orbit (LUMO) level of the luminescent polymers, thereby lowering the device efficiency. In this work, by introducing solution-based titanium oxide (TiOx) thin film as an electron injection layer between the polymer and Al electrode, we demonstrate that the devices exhibit an enhanced efficiency. The TiOx layer reduces the barrier height between the polymer and aluminum (Al) cathode, thereby facilitating the electron injection in the devices.