Conducting fluorocarbon coatings for organic light-emitting diodes

Conducting fluorocarbon coatings (CFx) have recently been used as an anode buffer layer in organic light-emitting diode (OLEDs) for enhancement of stability and carrier injection. The effect of CFx on OLEDs was related to its conductivity. We found the resistivity of poorly conducting (about 1010 Ω cm) CFx coatings can be substantially decreased to 105 Ω cm by either near UV or Ar ion irradiation. OLEDs were prepared on untreated and treated CFx for performance comparison. The UV treatment of CFx improved the device performance, while the Ar ion treatment led to deterioration. X-ray photoelectron spectroscopy analysis showed the UV treatment created graphitic regions leading to the higher conductivity of the CFx layer but the underlying indium tin oxide (ITO) anode remained intact. In contrast, argon ion bombardment caused damage to the ITO anode which contributed to poor device performance, although the CFx conductivity was similarly increased.