Efficiency of Light Outcoupling Structures in Organic Light‐Emitting Diodes: 2D TiO₂ Array as a Model System

Abstract

Organic light-emitting diodes (OLEDs) are widely used in research and are established in the industry. The building block nature of organic compounds enables a vast variety of materials. On top of that, there exist many strategies to improve the light outcoupling of OLEDs making a direct comparison of outcoupling technologies difficult. Here, a novel approach is introduced for the evaluation of light outcoupling structures. The new defined "efficiency of light outcoupling structures" (ELOS) clearly determines the effectiveness of the light outcoupling structure by weighting the experimental efficiency enhancement over the theoretical outcoupling gain. It neither depends on cavity design nor on the chosen organic material. The methodology is illustrated for red phosphorescent OLEDs comprising internal and external light outcoupling structures. Assumptions and further uses are discussed with respect to experimental and theoretical handling. In addition, the ELOS is calculated for various outcoupling techniques from literature to demonstrate the universality. Finally, most suitable reference OLEDs are discussed for application of light outcoupling structures. The presented approach enables new possibilities for studying light outcoupling structures and improves their comparability in a highly material-driven research field.

Tailor-made nanostructures bridging chaos and order for highly efficient white organic light-emitting diodes

“…Considering the influence of the leakage current, together with the mode distribution for the planar white OLEDs (Supplementary Note 2, Supplementary Fig. 11, and Supplementary Tables 7 and 8), we estimate the efficiency of light outcoupling structures (ELOS, Supplementary Note 3) for these nanostructures to be as high as 36.6% based on highly optimized white OLEDs 53 .…”

Directional Polarized Light Emission from Thin‐Film Light‐Emitting Diodes

“…On the other hand, since we need to have a thick ETL to suppress the air mode, this thermally evaporated thick ETL will render the top cathode to be almost planarized (Figure 4a). [ 31 ] As a result, the diffraction of both the TM waveguide and SPP modes is strongly suppressed. The residual corrugation depth is not sufficient to extract the TM modes, as they have shorter propagation length due to the absorption from the metal.…”

27‐4: Organic Light‐Emitting Diodes with Directional Polarized Light Emission

“…2a). [11] As a result, the diffraction of both the TM waveguide and SPP modes is strongly suppressed. The residual corrugation depth is not sufficient to extract the SPP and TM modes, as they have shorter propagation length due to the absorption from the metal.…”