The effect of C60 doping on the device performance of organic light-emitting diodes

The effect of C60 doping in the hole transport layer on the device performance of phosphorescent light-emitting diodes was investigated by changing the C60 content from 0% to 3%. Doping of C60 in 1,3,5-tris(N,N-bis-(4,5-methoxyphenyl)-aminophenyl)benzol resulted in efficient hole injection and low driving voltage at high luminance. In addition, the lifetime of the phosphorescent device was improved significantly by introducing a C60 molecule in the hole transport layer. The C60-doped device showed an extended lifetime of 1400 h compared with 700 h of the undoped device.