Improved Interconnecting Structure For A Tandem Organic Light Emitting Diode

摘要

Two-unit tandem organic light emitting diodes (OLEDs) employing two kinds of interconnecting structures, i.e. 5 nm lithium carbonate doped PTCDA (1:2 Li_2CO_3:PTCDA)/5 nm MoO_3 and 5 nm Li_2CO_3 doped BCP (1:4 Li_2CO_3:BCP)/5 nm MoO_3, have been fabricated, where PTCDA and BCP stand for 3, 4, 9, 10 perylenetetracarboxylic dianhydride and bathocuproine, respectively. Compared to the tandem OLED using the interconnecting structure of 5 nm 1:4 Li_2CO_3:BCP/5 nm MoO_3, the one utilizing 5 nm 1:2 Li_2CO_3:PTCDA/5 nm MoO_3 showed nearly same power efficiency and decreased operating voltage, mainly attributed to the higher electron conductivity of 1:2 Li_2CO_3:PTCDA relative to 1:4 Li_2CO_3:BCP. The charge generation and electron injection processes based on the interconnecting structure of 5 nm 1:2 Li_2CO_3:PTCDA/5 nm MoO_3 were also discussed. We provide a simple and effective connecting structure to enhance the current conduction for tandem OLEDs.