Characteristics of polymer light emitting diodes with the LiF anode interfacial layer

Electrical and electroluminescent characteristics of poly(2-methoxy-5- (2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEHPPV)-based polymer light emitting diodes (PLEDs) with the LiF anode interfacial layer were investigated. Current-voltage measurement and impedance analysis showed that LiF insertion affected the electrical properties of PLEDs notably. The maximum luminance efficiency of the PLED device with a LiF anode interfacial layer of 1-nm-thick was 3.01m/W, which is higher than 1.971m/W of the PLED device without a LiF layer. By inserting LiF as the anode interfacial layer, excess injection of holes from indium tin oxide anode can be reduced and hence the balance between electrons and holes can be increased in the emitting layer to improve device efficiency.