Correlation of Current Noise Behavior and Dark Spot Formation in Organic Light-Emitting Diodes

A correlation between current 1/f noise and dark spot formation is reported. Our results show that the dark spot is primarily correlated to current 1/f noise slope; the higher the slope, the poorer the interface, and the more abnormal dark spot growth rate and the shorter lifetime. Besides, there is a correlation between current 1/f noise magnitude and the dark spot initial size. A higher 1/f noise magnitude generally indicates a larger dark spot initial size. A seemingly identical current-voltage curve does not render the same characteristics of dark spot formation, which can be clearly distinguished from the subtle difference in 1/f noise behavior. The noise measurement can be used to predicate device lifetime and degradation behavior.