Significant color space blue-shift of green OLED emitter with sustaining lifetime and substantial efficiency enhancement

Abstract

In this study, we demonstrate that by embedding a plasmonic coupling metal layer beneath the active layer of an organic light-emitting diode, the resultant device is capable of inducing significant blue shifts in CIE color space coordinates of emitting light from the green emitting material without compromising the lifetime of the parent material. The implemented device consists of multilayers of organic emitting materials sandwiched by two thin metal layers to form a metal-dielectric-metal (MDM) cavity-like structure. The original green emission with CIE coordinates of (0.22, 0.56) was significantly color space blue-shifted to CIE coordinates of (0.10, 0.53). The MDM device exhibits an efficiency of 62 cd/A at a luminance of 1000 cd/m2, which represents a two-fold enhancement of current efficiency. Moreover, the spectral peak intensity is 4.3 times higher than that in a conventional device, which is much higher than that expected for an optical microcavity model, suggesting that the Purcell effect resulting from the coupling of surface plasmon waves may contribute to the extra enhancement of emission intensity.

Effect of trapped electrons on the transient current density and luminance of organic light-emitting diode

“…Organic light-emitting diode (OLED) is an important display and lighting technology with the advantages of self-emissive, thin, fast response time, and suitable for flexible device, which shows great achievements in efficiency improvement and lifetime elongation [1,2]. In such a device, electrons and holes inject from the electrodes into the organic stacks, and recombine to form the excitons which radiatively relax the energy for light emission.…”

Color-Tunable Organic Light Emitting Diodes for Deep Blue Emission by Regulating the Optical Micro-Cavity

“…As is known, an optical cavity can be formed in OLEDs by using high refractive index metallic electrodes [ 19 , 20 , 21 , 22 , 23 ] or DBR [ 24 , 25 , 26 ] composed of semi-conductors with a low and high ordered refractive index arrangement. Generally, metal electrodes are the preferred choices for their easy fabrication.…”

“…This shows that the optical cavity in OLEDs enhances the emission solely at a particular color and suppresses others in the meantime, which is called micro-cavity. Li et al reported that the micro-cavity structure markedly improves the efficiencies of green organic light-emitting diodes with a spectral peak intensity 4.3 times higher than that in a conventional device and a two-fold enhancement of the current efficiency [ 21 ], while the luminance enhancements of blue and red micro-cavity devices are small.…”