The Effect of the Oxygen Plasma Treatment for ITO and ZnO Nanorods on the Electroluminescence of ZnO Nanorod/MEH-PPV Heterostructure Devices

Series devices of ITO/ZnO/ZnO nanorods/MEH-PPV/Al have been fabricated. ITO and ZnO nanorods of some devices are treated by O₂ plasma. The electroluminescence of different devices is detected under different biases. UV electroluminescence of ZnO nanorods at 380 nm is observed in all the devices. The intensity of 380 nm increases when both ITO and ZnO nanorods are treated. The turn-on voltage of the treated device is lower than that of the non-treated device, and the EL power is enhanced. When the thickness of MEH-PPV is sufficiently thin, only 380 nm electroluminescence, besides a weak defect emission at 760 nm, is detected. The enhancement mechanism of the electroluminescence of the treated devices is discussed.