Ag/ZnS/Ag (AZA) multilayer films with various ZnS interlayer
thicknesses
were deposited on glass substrates via thermal vacuum evaporation.
The sheet resistances, work functions, transmittances, and reflectances
of the AZA structures were characterized to evaluate whether their
electrical and optical properties are suitable for application as
organic light-emitting diode (OLED) electrodes. The transmittance
peak and reflectance dip could be red-shifted by changing the interlayer
thickness of the AZA structure, which resulted in a surface plasmon
(SP) color filter effect. OLED devices with AZA multilayers of different
interlayer thicknesses were then fabricated. Instead of the expected
red shift in the emission spectrum due to the surface plasmon color
filter effect of the AZA structure, two electroluminescence (EL) peaks
were obtained in the AZA OLEDs with 45 and 60 nm thick ZnS interlayers.
From the results of the finite-difference time-domain calculations,
we conclude that the two split EL peaks are attributed to mode coupling
between the optically active surface plasmons of the AZA structure
and the microcavity of the OLED structure. The proposed OLED design
with a metal/dielectric/metal electrode allows the control of the
EL spectral shape and emission color without changing the thickness
of the OLED organic layers.