Degradation Analysis of Organic Light-Emitting Diodes through Dispersive Magneto-Electroluminescence Response

Abstract

Understanding the stability and degradation of organic light-emitting diodes (OLEDs) under working conditions is a significant area of research for developing more effective OLEDs and further improving their performance. However, studies of degradation processes by in situ noninvasive methods have not been adequately developed. In this work, tris-(8-hydroxyquinolino) aluminum (Alq3)-based OLED degradation processes have been analyzed through the investigation of the device dispersive magneto-electroluminescence (MEL­(B)) response measured at room temperature. By studying the change in the MEL­(B) response during the device degradation under different external stimuli, such as exposing the device to the atmosphere and prolonged illumination by a strong visible light source, we have gained insight into the microscopic spin-dependent phenomena that control the recombination of e–h polaron pairs in the device. We found that the device degradation leads to a shorter e–h polaron lifetime, smaller dispersive parameter, and broader lifetime distribution function that shows increased disorder in the active layer. This study could offer a potential tool that may be beneficial for assessing the degradation of OLED devices based on various active layers.

Hybridized Local and Charge-Transfer Excited-State Emitter for a Blue Organic Solid-State Laser

“…This trend is maintained at a higher voltage of 5 V. According to the Merrifield theory, this trend is completely different from that of TTF-based devices, which display a weakened MEL signal at the high-magnetic-field region (50–250 mT). Furthermore, the magnetic field indicating half of saturated MEL intensity (B 0 ) was ∼18.2 mT, which is over the conventional B 0 region showing a sharp increase by hyperfine field interaction (HFI) between 4 and 10 mT . This suggests the presence of a mechanism that is more dominant than HFI.…”

“…Furthermore, the magnetic field indicating half of saturated MEL intensity (B 0 ) was ∼18.2 mT, which is over the conventional B 0 region showing a sharp increase by hyperfine field interaction (HFI) between 4 and 10 mT. 31 This suggests the presence of a mechanism that is more dominant than HFI.…”

Unraveling Degradation Processes and Strategies for Enhancing Reliability in Organic Light-Emitting Diodes

“…When a device fails, it is usually due to electrical short circuits, the most severe type of failure. These shorts occur due to imperfections on the surface of the device's substrate, such as particles, rough surfaces, or local heating during operation [45][46][47][48]. The heat generated by these imperfections can also cause structural changes in the device, potentially leading to electrode contact or damage to the cathode material [49][50][51].…”

“…Wang et al categorized the decay stages into three categories to better understand the decay behavior [79]. Additionally, Aziz et al identified dark-spot degradation, catastrophic failure, and intrinsic deterioration as the main causes of OLED luminance loss [48]. Ishii et al explained that luminance decay occurs in two phases, exponential decay due to chemical degradation and a quick downward movement due to an internal electric field [80].…”