Microstructure Evolution of Thermally Deposited Alq ₃ Thick Films With Deposition Temperature and Time

In this study, Alq 3 thick films were fabricated by thermal deposition under controlled temperature and deposition time to investigate phase‐specific variations in crystal growth morphology. With increasing deposition temperature and time, Alq 3 exhibited a columnar growth morphology, accompanied by an increase in surface roughness. To examine the electrical implications of thickness and morphological variations, electron‐only devices (EODs) were fabricated. The measured resistivity values were higher than the theoretical predictions, and measurement deviations were observed depending on the surface roughness of the thick films. These results suggest that the columnar growth morphology of Alq 3 can hinder effective interlayer contact in vertically stacked organic light‐emitting diode (OLED) structures. Such morphological nonuniformity may induce localized charge accumulation, potentially leading to device degradation and a reduced operational lifetime.