Buffer-enhanced electron injection in organic light-emitting devices with copper cathode

• We explore in this work the use of Cu as a cathode material in organic light-emitting devices (OLEDs) and find a dual electron–injection enhancement mechanism derived from the LiF layer. Different from what observed previously in Ag- and Au-cathode devices, the LiF buffer layer in the Cu-cathode OLEDs starts to play its role in performance improvement when it is much thinner than 3 nm, the optimal value of buffer thickness, and in the case of optimal thickness, the device exhibits excellent performance comparable to conventional Al-cathode device. The phenomenon observed is ascribed to enhanced electron injection as a result of combined effect of interfacial reaction and tunneling barrier reduction mechanism: while chemical reaction plays a key role at the very beginning of interface formation, tunneling dominates in the subsequent stage leading to the tremendous improvement of the characteristics.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

Interface modification; Cu cathode; Composited mechanism; Organic light-emitting devices; Energy level alignment

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