Organic light-emitting
diodes (OLEDs) have been widely used, particularly
in display applications. OLEDs are easily degraded without stringent
encapsulation owing to their susceptibility to water vapor and oxygen.
Therefore, establishing an effective protection method for these devices
is essential. In this study, we demonstrate the device protection
performance and improvement in color purity by introducing CaF
2
/ZnS multilayered films on a top-emitting inverted-type OLED
(iOLED), which was originally intended to act as a distributed Bragg
reflector (DBR). To test the protection performance of each dielectric
layer, conventional bottom-emitting OLEDs (cOLEDs) with and without
single layers of CaF
2
and ZnS were investigated for comparison.
All OLEDs were stored in an atmosphere without stringent encapsulation,
such as a cover glass. The luminescence area of cOLEDs without the
dielectric film decreased by more than 90% after 3 days of fabrication.
In contrast, the dark-spot formation was moderated after the same
period for the dielectric single-layer deposited cOLEDs. Notably,
the iOLED with DBR completely preserved the emitting area even after
2 months of fabrication. This suggests that DBR acted as a protective
film for the organic layer, whereas the inverted structure also contributed
to reducing the degradation of air- and moisture-sensitive materials.