Presentation
19 September 2017 Investigating the causes of the lower stability of solution-coated versus vacuum-deposited small-molecule organic light emitting devices (Conference Presentation)
Hany Aziz, Yong Joo Cho, Hyeonghwa Yu, Yingjie Zhang
Author Affiliations +
Abstract
Although the promise of realizing lower cost fabrication by means of solution-based processing techniques, such as spin coating, web coating or inkjet printing, has been one key driver behind the interest in OLEDs for the last two decades, the lower stability of devices made by these techniques has been a long standing issue. With recent advances in developing solution-processable small molecule materials, it is now possible to make OLEDs of the same small molecule materials by either solution coating or vacuum deposition. Despite this, there continues to be an intriguing stability gap. In this work, we investigate this phenomenon with the purpose of identifying its root causes. Electroluminescence, delayed electroluminescence and photoluminescence measurements are used to study and compare between the aging behavior in OLEDs made by spin-coating versus vacuum-deposition. Hole-only devices are also utilized, and employed to study the effects of charges and excitons, separately and combined. The results reveal that the faster degradation of solution-processed devices relative to their vacuum-deposited counterparts under electrical stress is due to a faster molecular aggregation process. Excitons and interactions between them and polarons appear to play a leading role in inducing this phenomenon. Results from these investigations will be presented and discussed.
Conference Presentation
© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hany Aziz, Yong Joo Cho, Hyeonghwa Yu, and Yingjie Zhang "Investigating the causes of the lower stability of solution-coated versus vacuum-deposited small-molecule organic light emitting devices (Conference Presentation)", Proc. SPIE 10362, Organic Light Emitting Materials and Devices XXI, 103620R (19 September 2017); https://doi.org/10.1117/12.2276696
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KEYWORDS
Organic light emitting diodes

Coating

Electroluminescence

Excitons

Molecular aggregates

Molecules

Fabrication

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