A study on application of N&K Analyzer in OLED failure analysis

The thickness of each layer of the OLED (Organic Light Emitting Diode) with the multi-layer structure of ITO/NPB/Alq3/LiF/Al was studied by N&K Analyzer before and after aging experiments. Through comparing the film thickness when kept in ambient atmosphere with different exposure duration and failed samples, main thickness changes occur in the Alq3 and LiF layers while the ITO and NPB layer had no dramatic changes in thickness. The trend is Alq3 layer decrease and LiF layer increase in the process of failure. Before electrical failure, the devices exhibit good uniformity in film thickness; but when electrical failure occurs, this uniformity has obviously been destroyed. So it is proved that N&K Analyzer is an effective new method for OLED failure analysis especially in the condition that it is very difficult to characterize the OLEDpsilas multi-ultra thin-layer structure by traditional means.