Minor Copper-Doped Aluminum Alloy Enabling Long-Lifetime Organic Light-Emitting Diodes

Abstract

Aluminum has been extensively used as a conductor material in numerous electronic devices, including solar cells, light-emitting diodes (LEDs), organic LEDs (OLEDs), and thin-film transistors. However, its spiking surface and easy electromigration have limited its performance. To overcome this, a trace amount of nonprecious copper dopant has been proven effective in enhancing device reliability. Nevertheless, a comprehensive investigation regarding the effect of copper doping on the morphology at the aluminum conductor−organic interface is yet to be done. We had hence fabricated a series of green OLED devices to probe how copper doping affected the aluminum conductor, morphologically and electrically, and the corresponding device's efficiency and lifetime performance. We found 4 wt % copper doping to be highly effective in enabling a spike-less and smoother aluminum interface, which in turn enabled the fabrication of devices with much higher efficiency and lifetime. Specifically, the corresponding power efficacy at 1000 cd/m 2 was increased from 32 to 42 lm/W and the lifetime increased from 75 to 263 h, an increment of 250%. Atomic force microscopy confirmed that the copper doping did help smooth out the conductor interface as deposited and reduce electromigration upon operation.

EIS Study of Doped High-Entropy Alloy

“…This is because these metals can form strong carbides or nitrides, which act as strengthening agents and can also improve wear and corrosion resistance. Similarly, doping copper into aluminum [20] can improve its electrical conductivity, while doping aluminum into copper [21] can improve its strength and corrosion resistance. Doping with other metals such as magnesium, zinc, or nickel [22,23] can also modify the properties of aluminum alloys, depending on the specific application.…”