OLED Pixel Shrinkage Dependence with Cathode Influenced by Thermal Effect

Technical status of top-emission organic light-emitting diodes

“…The reported 20 nmthick co-doped Mg:Ag (10:1) cathode showed a very high reflection of 41.7%, which resulted in a strong microcavity effect between the two reflective electrodes of the TEOLED [81]. However, the Mg:Ag (10:1) cathode shows low transmittance (33.4%) due to the high extinction coefficient of Mg and exhibits high sheet resistance (33.4%), which affects the TEOLED efficiency [81,82]. Recently, S. Kwon et al optimized the ratio of Ag in a co-doped Mg:Ag cathode to produce high-efficiency TEOLEDs [81].…”

“…Also, the TEOLEDs with the 1:10 Mg:Ag composition showed strong pixel shrinkage and a short lifetime under UV exposure and the operating conditions. Particularly, in the case of the co-doped Mg:Ag film (1:10), the Mg atoms can be migrated toward the CPL under the UV irradiation or operating conditions due to its self-diffusion property, whereas the Ag atoms aggregated toward the EIL, which resulted in a poor electron injection property and reduced device efficiency [82,83] (Figure 7). Although the Mg:Ag cathode-based TEOLED with a 1:10 ratio showed higher efficiency than that with a 10:1 ratio, the stability of this electrode under the operating conditions could be a major issue for real applications.…”