High-Color-Stability and Low-Driving-Voltage White Organic Light-Emitting Diodes on Silicon with Interlayers of Thin Charge Generation Units for Microdisplay Applications

Abstract

In this research, we report white organic light-emitting diodes on silicon (OLEDoSs), with low driving voltage and high color stability, according to the luminance change for a microdisplay in virtual reality (VR) and augmented reality (AR) applications. The driving voltage for the OLEDoS is restricted owing to the highly integrated complementary metal-oxide-semiconductor backplane, whose subpixel size is of the order of several micrometers. Therefore, the low driving voltage of the OLEDoS is crucial for securing high luminance and low power consumption. Herein, thin charge generation units (CGUs) with a lithium-doped electron transport layer of 5 nm thickness and 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile of 5 nm thickness were introduced as interlayers between the phosphorescent yellowish-green and fluorescent blue-emitting layers. The OLEDoS with a thin CGU showed significant enhancement of a driving voltage of 5.8 V at 1000 cd/m(2) luminance and a cool-white emission with (0.276, 0.382) color coordinates compared with general tandem devices. Despite the relatively low current efficiency, the power efficiency was comparable to that of the general tandem device at high luminance values over 1000 cd/m(2) without dramatic roll-off. Moreover, with respect to color stability, a color coordinate change of (+/- 0.007, +/- 0.006) was achieved in the 500-2000 cd/m(2) luminance region. Therefore, it is anticipated that the aforementioned architecture is useful for OLEDoS-based microdisplays for VR and AR applications.