Molecular Design and Device Design to Improve Stabilities of Organic Light-Emitting Diodes

Although organic light-emitting diodes (OLEDs) with internal quantum efficiencies of approximately 100% have been demonstrated using phosphorescent or thermally activated delayed fluorescent (TADF) emitters, the lifetimes of OLEDs have seldom been discussed owing to the complicated degradation mechanism. To realize OLEDs for practical applications, it is essential to extend their lifetimes. In recent years, attempts to improve the stability of OLEDs have been increasingly reported. One approach is to prevent the decrease in brightness resulting from OLED operation, so-called improvement of the operational stability. Another approach is to prevent the decrease in light-emitting area caused by oxygen/moisture, so-called improvement of the air-stability. In this review, molecular design and device design to improve the stability of OLEDs are introduced.