Influence of connecting units’ thicknesses on tandem organic devices’ performances

The present work investigates the influence of the Alq3:Mg and MoO3 thicknesses in the connecting unit on the performance of tandem organic light-emitting devices (OLEDs). By systematically varying the Alq3:Mg and MoO3 thicknesses, we obtained a higher current efficiency of 37.3 cd/A for a device with 30 nm Alq3:Mg and 3 nm MoO3 layer as connecting units. The optimal device performance is enhanced by at least 14%, compared with those of devices we fabricated in this paper. It suggests that appropriate Alq3:Mg and MoO3 thicknesses can enhance the charge generating ability for connecting units. On the other hand, it was found that the charge transporting layer would decrease strongly because of much thicker or thinner MoO3 thicknesses. The results demonstrate that it is an effective method to improve the performance of OLEDs by using a optimal thickness for Alq3:Mg and MoO3 layers.