White stacked OLED with 38 lm/W and 100,000‐hour lifetime at 1000 cd/m² for display and lighting applications

Abstract

Abstract— The three critical parameters in determining the commercial success of organic light‐emitting diodes (OLEDs), both in display and lighting applications, are power efficiency, lifetime, and price competitiveness. PIN technology is widely considered as the preferred way to maximize power efficiency and lifetime. Here, a high‐efficiency and long‐lifetime white‐light‐emitting diode, which has been realized by stacking a blue‐fluorescent emission unit together with green‐ and red‐phosphorescent emission units, is reported. Proprietary materials have been used in transport layers of each emission unit, which significantly improves the power efficiency and stability. The power efficiency at 1000 cd/m2 is 38 lm/W with CIE color coordinates of (0.43, 0.44) and a color‐rendering index (CRI) of 90. An extrapolated lifetime at an initial luminance of 1000 cd/m2 is above 100,000 hours, which fulfils the specifications for most applications. The emission color can also be easily tuned towards the equal‐energy white for display applications by selecting emitting materials and varying the transport‐layer cavities.

Homogeneous dispersion of organic p-dopants in an organic semiconductor as an origin of high charge generation efficiency

“…[3][4][5][6][7][8] Such high doping concentration limits the application of doping technology in organic semiconductors because the diffusion of dopants can destabilize organic electronic devices. 9,10 In previous papers, we reported that a diverse range of charge generation efficiencies were obtained for various combinations of p-dopants and hosts. 6,7 The charge generation efficiencies of p-dopants depended on the energy difference between the highest occupied molecular orbital ͑HOMO͒ level of the hosts and the lowest unoccupied molecular orbital ͑LUMO͒ level of the dopant ͑⌬E = E HOMO,host − E LUMO,dopant ͒.…”

Singlet Generation from Triplet Excitons in Fluorescent Organic Light-Emitting Diodes

“…The displays employ red phosphorescent emitters but blue and green fluorescent emitters. In the latest generation of high-efficiency (>60 lm/W) organic solid-state lighting (OSSL) panels from Novaled, Osram, and Konica Minolta-Philips, use of all phosphorescent emitters yields very warm white colours, with poor colour temperatures of 2600 K, and poor lifetimes especially for the blue component [1][2][3]. The phosphorescent emitters lack good saturated colour but more importantly the blue metal organic complexes used are unstable.…”

Organic Semiconductor Electroluminescent Materials

“…However, the dopant is sensitive to air, and can only be handled in an inert atmosphere. Later, they announced an air stable n-type dopant NDN26 [80,81], although the material structure has not been disclosed.…”

“…As the increase of voltage drop over the entire doped transport layer with respect to thickness is very small, it makes it possible to optimize resonant light outcoupling with strong microcavity without impacting on charge carrier balance [81].…”