Influence of vacuum chamber impurities on the lifetime of organic light-emitting diodes

Abstract

We evaluated the influence of impurities in the vacuum chamber used for the fabrication of organic light-emitting diodes on the lifetime of the fabricated devices and found a correlation between lifetime and the device fabrication time. The contact angle of the ITO substrates stored the chamber under vacuum were used to evaluate chamber cleanliness. Liquid chromatography-mass spectrometry was performed on Si wafers stored in the vacuum chamber before device fabrication to examine the impurities in the chamber. Surprisingly, despite the chamber and evaporation sources being at room temperature, a variety of materials were detected, including previously deposited materials and plasticizers from the vacuum chamber components. We show that the impurities, and not differences in water content, in the chamber were the source of lifetime variations even when the duration of exposure to impurities only varied before and after deposition of the emitter layer. These results suggest that the impurities floating in the vacuum chamber significantly impact lifetime values and reproducibility.

52.4: Toward Longer Lifetime‐‐Elongating the Operation Lifetime of Organic Lighting Emitting Diode by Implementing Novel Driving Method

“…As known to all, stability of OLED was attributed to both intrinsic and extrinsic reasons. The extrinsic reasons depend on many factors, such as flatness of substrate [6,7] , the delamination of organic and cathode layers [8] , particle contamination, vacuum level as well as tact time in the fabrication process [9] . With good encapsulation process, the extrinsic factors can be improved well.…”

76‐3: Induction Heating Evaporator for the Fabrication of OLEDs

“…The issue is not related only to the throughput time but also to the device reproducibility. A longer duration of vacuum process leads to a variation in OLED lifetimes since the impurities floating in the vacuum chamber significantly impact the lifetime values [5]. Therefore, it is a serious challenge in production of OLEDs to minimize the idling time in vacuum by enabling a fast-response evaporation.…”

Construction of a Small-Scale Vacuum Generation System and Using It as an Educational Device to Demonstrate Features of the Vacuum

“…We explored some other similar works related to small-scale vacuum generation, and found that different methods were used to create vacuum and different designs exist for the vacuum chambers. There are several applications of the generated vacuum (Jayaram and Gonzalez, 2011;Tripathi et al, 2012;Fujimoto et al, 2017), and a specific application may favor one method over the others.…”