High efficiency red top-emitting micro-cavity organic light emitting diodes

Abstract

In this study, we present optical simulation versus real fabricated device results in the micro-cavity red top-emitting organic light emitting diodes (TEOLEDs). The optical simulation results indicate that the two kinds of possible emissive layer (EML) positions exist in the second order micro-cavity effect and each EMLs could emit the similar radiance with near National Television System Committee (NTSC) color coordinate. Expected current efficiency and external quantum efficiency by the optical simulation toward the surface normal in the red tandem TEOLED are 98.8 cd/A and 22.6% for two EMLs, while fabricated device shows 95.8 cd/A and 26.5%, respectively.

Device performances of third order micro-cavity green top-emitting organic light emitting diodes

“…Recently, we have reported the analysis of simulated microcavity device performances with available optical constants and it showed a good agreement with the results of real fabricated devices [10]. Fig.…”

“…The expected efficiency of TEOLEDs with only light out-coupling difference at the same current density (1.76 mA/cm 2 ) can be calculated using earlier reported method [10,12]. The current efficiencies of designed TEOLEDs are calculated at the several EML positions when the cavity effect of TEOLEDs clearly gives a spectral peak at 530 nm from the original broad emission spectrum of BEOLED device.…”

“…These values are lower than the 2nd order cavity thick HTL TEOLED (CE = 101.0 cd/A and EQE = 15.2% at the current density of 1.76 mA/cm 2 ). For the simulation, refractive index and extinction coefficient values of organic materials and electrodes were taken from the earlier report [10]. The estimated Commission Internationale de l'Eclairage (CIE) 1976 color coordinate shift of this 3rd order device is (0.01, 0.05) for the viewing angle in the range from 0 to 60 degree.…”

“…The NPB on the Mg:Ag cathode was used as capping layer to enhance their transmittance [15]. Thick non-metal doped ETLs were used in the 3°CE-OLED1 since the metal dopant for high electron conductivity suppresses the micro-cavity effects due to the influence of scattering [10].…”

“…The optical simulation was used to design the structure of TEOLEDs with the micro-cavity effect. Such optical simulation for the structure design of micro-cavity devices is essential as the possible emissive layer (EML) location in the cavity has limited latitude unlike the non-cavity devices [10]. The real TEOLED devices were fabricated by employing the knowledge of simulation results.…”