Dislocated output coupling within a selected band in an OLED based on an in-plane DBR microcavity array

Abstract

Periodic arrays of microcavities based on distributed Bragg reflectors (DBRs) are introduced into organic light-emitting diodes (OLEDs). The electroluminescence (EL) confined both within the DBR microcavity and inside the indium tin oxide layer is coupled out through interaction with the grating structures, so that a narrow-band portion of the EL is picked up by multiple grating–diffraction processes with the aid of the waveguide effect in the substrate. This selected EL spectrum is coupled out of the device at a separate location with a distance greater than 4 mm from the direct output for a substrate with a thickness of 1.1 mm. Meanwhile, optical gain inside the microcavity and through inter-microcavity coupling leads to the amplification of the EL, so that the band-narrowing effect is observed with increasing applied voltage for the dislocated output. A minimum bandwidth of 26 nm was measured for the dislocated output coupling, which is a significant narrowing with respect to the direct output with a bandwidth >100 nm.