Realization of Low Driving Voltage in Organic Light-Emitting Diodes Using C60 as an Electron Transport Layer and Alq3 as a Buffer Layer

Organic light-emitting diodes with low driving voltage based on fullerene
$({\rm C}_{60})$
as an electron transport layer and tris (8-hydroxyquinolinato)-aluminum
$({\rm Alq}_{3})$
as a buffer layer are successfully fabricated. For the optimal device with structures of ITO/NPB (40 nm)/
${\rm Alq}_{3}$
/(30 nm)/
${\rm C}_{60}$
(20 nm)/
${\rm Alq}_{3}$
(3 nm)/LiF (0.8 nm)/Al (120 nm), the turn-on driving voltage is 2.8 V, which is reduced 0.4 V compared with that of the control device. Meanwhile, the driving voltage of 4.9 V has been achieved at a luminance of 1000
${\rm cd}/{\rm m}^{2}$
in this device, which is reduced 1.8 V compared with that of the control device. The results have a significant effect on the commercialization application of the devices.