Efficient hole injection in organic light-emitting diodes using C60 as a buffer layer for Al reflective anodes

The hole injection of the organic light-emitting diodes with Al as a reflective anode for top-emitting devices was improved by using C60 as a thin buffer layer between Al and a hole transport layer. The driving voltage of the devices with C60 buffer layer was 5.5V compared with 11V for the devices without C60 buffer layer. The decrease of interfacial energy barrier by interface dipole formation between Al and C60 contributed to the low driving voltage of the devices.