Nanoscale investigation of moisture-induced degradation mechanisms of tris(8-hydroxyquinoline) aluminium-based organic light-emitting diodes

Abstract

By exploiting tapping mode atomic force microscopy, the moisture-induced degradation mechanisms of ITO (indium tin oxide)-coated glass/CuPc (copper phthalocyanine)/NPB (N, N′-di(naphthalene-1-yl)-N, N′-diphthalbenzidine)/Alq3 (tris(8-hydroxyquinoline) aluminium)-based organic light-emitting diodes without cathode were investigated. It is found that three types of degradation mechanisms are associated with moisture-exposed Alq3 films, when the device is exposed to moisture, namely, hydration of Alq3, crystallization of Alq3 and reaction of the Alq3 complex with H2O. Crystallization of the NPB layer of ITO/CuPc/NPB was observed on exposure to moisture, and de-wetting simultaneously takes place at the interface of CuPc/NPB. Indium and/or oxygen may diffuse from ITO into the organic layers. These observations provide a clear picture of the moisture-induced degradation mechanisms of the ITO/CuPc/NPB/Alq3-based OLEDs.

Low-temperature remote plasma enhanced atomic layer deposition of ZrO2/zircone nanolaminate film for efficient encapsulation of flexible organic light-emitting diodes

“…Organic light-emitting diodes (OLEDs) are considered as the most promising candidate to produce displays because of the high flexibility of organic materials67. However, there are also some significant disadvantages including the problems of long-term stability and reliability of OLEDs because both the organic materials and cathode metals are vulnerable to atmospheric moisture and oxygen89. To take the full advantage of OLED potential, effective encapsulation is required to solve long-term stability and lifetime problems.…”

Visualization of thermally-activated degradation pathways of tris(8-hydroxyquinoline) aluminum thin films for electroluminescence application

“…As far as O 2 influence on degradation of OLEDs is concerned, it seems that O 2 has little effect on the degradation of Alq 3 film as discussed above. However, it has shown that an O 2 ambient in presence of moisture has a serious effect on the interface degradation between organic layer and cathode [21]. Fig.…”

Some Metal Complexes of 9-Hydroxyphenalenone as Novel Electron Transporting Materials for OLEDs

“…They oxidized and hydrolyzed readily by traces of oxygen and water in real devices. Besides, the crystallization if initially amorphous material can take place during exploitation of the device [4][5][6][7]. Thus search of new metal complexes deprived of such disadvantages is of importance.…”