Top-emitting organic light-emitting device with high efficiency and low voltage using a silver–silver microcavity

A systematic study on efficiency enhancements in phosphorescent green, red and blue microcavity organic light emitting devices

“…A semitransparent metal electrode such as a thin Ag layer is mostly commonly used due to its simple fabrication steps. 4,11,[13][14][15] However, a thin Ag layer does not provide a high enough reflectivity for a microcavity device. Because of the large extinction coefficient of a metal and of the presence of surface plasmon mode at the organic/metal interface, the use of semitransparent metal electrodes is not favorable for microcavity OLEDs.…”

Optimization of the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes on metal foils

“…In recent years there have been many reports of glass-based top-emissive OLEDs with good performance where Ag, 7,8 Al/Ag, 9,10 LiF/Al 12 and LiF/Al/Ag [12][13][14][15][16] have been applied as the transparent cathode, often in combination with a capping layer such as N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB), [10][11][12][13][14][15][16][17] N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD), 9 tris(8-hydroxyquinolinato)aluminium (AlQ3) 3 , 17,18 tin-doped indium oxide (ITO), SiO 2 , 15 or ZnSe. 16,19 With this second metal electrode, a microcavity resonator is obtained that amplifies a specific wavelength range and particular emission angles 15,20,21 (acting like a Fabry-Pérot filter).…”

Top-emitting organic light-emitting diodes integrated with thermally evaporated scattering film for reducing angular dependence of emission spectra

“…The strong light scattering ability of the TPE encourages us to explore its application as a top scattering layer for top-emitting OLEDs. It is well-known that the emission spectra of top-emitting OLEDs are highly dependent on the viewing angle, because the dominant emission wavelength is angularly modulated by kðhÞ ¼ k 0 Â cos h [5]. The emission color changes as the viewing angle is altered.…”

“…By setting the cavity length resonant with the emission wavelength, the top-emitting OLEDs can exhibit higher efficiency and purer color compared with their bottom-emitting counterparts [3,4]. However, the effective cavity length is angularly dependent which is determined by L eff ðhÞ ¼ L normal  cos h, where h is the viewing angle [5]. As viewing angle increases, the effective length is reduced, which results in a smaller resonant wavelength and thus a bluer emission color.…”