Highly-Efficient Solution Processed Yellow Organic Light Emitting Diode With Tungsten Trioxide Hole Injection/Transport Layer

Organic light emitting diodes (OLEDs) are emerging key technologies for full-color flat-panel displays and high-quality solid-state lighting sources. To achieve highly efficient OLED devices, the hole injection/transport layer is a key factor. Solution-processed transition metal oxides have promising potential, due to their balanced charge injection and efficient carrier mobility. Herein, we have demonstrated a solution-processed efficient yellow phosphorescent OLED with tungsten trioxide (WO3) hole-injection/hole-transport layer (HIL/HTL). The electroluminescent characteristics of PEDOT:PSS and WO3 based devices were studied. The WO3 based OLED exhibits maximum luminance of 10230 cdm ^-2 , the power efficiency of 35.9 lmW ^-1 , current efficiency 51 cdA ^-1 , and external quantum efficiency of 17.4%. Moreover, the resultant device also displays 45% higher power efficiency as compared to counterpart which exhibits PEDOT:PSS. The higher device performances of OLED device may be attributed to effective hole transporting ability, balanced charge carrier injection in the emissive layer, and non-acidic characteristic of HIL. Analysis of results illustrates an alternative tactic based on tungsten trioxide as a substitute of PEDOT:PSS for solution-processable energy-saving OLEDs.