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

Morphological phase transitions in films

“…A lot of measurements have been performed in this context by using different experimental approaches and, although some discussions are still going on, there are consistent indications that morphological changes (or glass transitions) occur in the range 130-175 C, whereas crystalline phases are formed above 185 C [2,6,7].…”

Effect of thermal annealing on the structural and optical properties of tris‐(8‐hydroxyquinoline)aluminum(III) (Alq3) films

“…One of the major factors responsible for device failure is the absence of encapsulation and thermal instability induced by joule heating during the operation of the OLEDs. The thermal stress in Alq 3 thin film-induced crystallization and device failure has been reported by Xu et al (5). Wang et al (4) reported the phase transition of Alq 3 powder to take place between 643 K and 669 K. Furthermore, they reported the melting and evaporation of Alq 3 is at 703 K. Most of the recent studies have been focused on the optimization of the device (6), to improve the stability of the device (7), the charge transport mechanisms (8,9) and the tuning of OLED emission spectrum (4).…”

“…The thermal stress in Alq 3 thin film‐induced crystallization and device failure has been reported by Xu et al . . Wang et al .…”

Dependence of dark spot growth on cathode/organic interfacial adhesion in organic light emitting devices

“…To ensure this, the cathode deposition temperature should be chosen below the T g of both NPB(95-96°C) [40] and Alq 3 (129-139°C) [44], so as to not induce any unwanted crystallization. In addition, metal deposition temperature above 100°C in a study by Gao [42] was seen to cause shorting of the device.…”