Effects of the thickness of DPVBi on the performance of WOLED

In order to study the effect of the thickness of DPVBi on the performance of WOLED, we constructed multilayer organic electroluminescent devices, the structure is ITO/2T-NATA (20 nm) / NPBX (15 nm) / DPVBi (x mn) / Rubrene (0.5 nm) / DPVBi ( x nm) / Rubrene (0.5 nm) / Alq3 (40 nm) / LiF (0.5 nm) / Al. Such structure takes full advantage of the hole blocking and luminous properties of DPVBi, and it is propitious to keep the balance of the blue light from DPVBi, the green light from Alq3 and the yellow light from Rubrene. Thus the device can emit white light which has better performance. The effects of the thickness of DPVBi on the performance of WOLEDs were discussed. When the thickness of DPVBi was changed from 10 to 25 nm and that other materials kept fixed, the device performance changed greatly. The best performance of the device was obtained when x = 20 nm. Its maximum luminance was 21195 cd/m² at 20 V driving voltage, and the maximum current efficiencies was 4.06 cd /A at 8 V driving voltage. The CIE coordinates of the device was (0.30, 0.32) , so it is WOLED.