Accelerated ageing of organic LED panels using ultraviolet exposure

Askola, Janne; Calkin, Yusuf; Vaskuri, Anna; Poikonen, Tuomas; Ikonen, Erkki

doi:10.1177/1477153518819654

Cited by 3 publications

(3 citation statements)

References 13 publications

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“…Recently, Askola et al studied the photo-degradation of two commercially available white OLEDs using UV radiation (one device exposed to uniform UV A/B radiation and the other to spectrally resolved UV radiation from 273 nm to 365 nm). 8 The UV exposure increased the luminance decay by at most a factor of eight compared to the natural aging observed from the same device. An effective way of addressing these issues, and improving the device efficiency and lifetime are vital if OLEDs are to achieve wide acceptance.…”

Section: Introductionmentioning

confidence: 94%

Degradation of OLED performance by exposure to UV irradiation

Kwon

Baek²,

Choi³

et al. 2019

RSC Adv.

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Organic light-emitting diode (OLED) displays are highly susceptible to the harsh environmental conditions found outdoors, like exposure to direct sunlight as well as UV radiation and storage temperature, resulting in a loss of luminance and lifespan, pixel shrinkage, and permanent damage and/or malfunction of the panel.Here, we fabricated top emission OLEDs (TEOLEDs) using Yb : LiF (1 : 1, 2 nm)/Ag : Mg (10 : 1, 16 nm) andMg : LiF (1 : 1, 2 nm)/Ag : Mg (10 : 1, 16 nm) cathode units and the performances of the devices were investigated by subjecting them to UV radiation. A fabricated red TEOLED (control device), employing a standard Mg : LiF (1 : 1, 2 nm) electron injection layer (EIL) and an Ag : Mg (16 nm) cathode, showed a rapid decrease in luminance and a fast increase in driving voltage at 10 mA cm À2 over time after UV irradiation for 300 h. However, a cathode unit comprising a Yb : LiF (1 : 1, 2 nm) EIL and an Ag : Mg (10 : 1, 16 nm) cathode showed no loss of luminance or increase in driving voltage at 10 mA cm À2 over time after UV irradiation for 300 h. Therefore, we investigated the changes occurring in both cathode units due to UV irradiation using the lift-out FIB-TEM technique and EDS mapping. With UV irradiation for 300 h, Ag atoms migrated toward the center of the cathode, Mg atoms migrated toward the CPL, and no Mg atoms were observed in the EIL area. In contrast, we observed (i) no substantial migration of Ag atoms and they were located at the center of the cathode, (ii) no migration of Mg atoms toward the CPL layer, and (iii) no movement of Yb atoms after UV irradiation. Furthermore, the UV irradiated red TEOLED with an Mg : LiF (1 : 1, 2 nm) EIL showed (i) deterioration in electron injection into the emissive layer (EML) and an increase in the EIL/metal interface resistance, and (ii) a remarkable shift of the J-V curve to the higher voltage side, while almost no such changes were observed in the TEOLD with a Yb : LiF (1 : 1, 2 nm) EIL. Also, an almost identical RGB pixel emitting area was noticed in the Yb : LiF (1 : 1, 2 nm) based devices after UV irradiation for 300 h. These results suggest that Yb could become a good candidate for the cathode unit, providing better device stability against harsh environmental conditions as well as excellent electron injection properties.

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Section: Introductionmentioning

confidence: 94%

Degradation of OLED performance by exposure to UV irradiation

Kwon

Baek²,

Choi³

et al. 2019

RSC Adv.

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“…It is important to highlight the keyword "energy efficiency" in this cluster as it has the highest number of occurrences (324) of the map (excluding the keywords present in query 1), therefore is of great interest in the research on building services [32][33][34][35][36][37]. The fourth cluster, in yellow, groups the "lighting" building service; this keyword has been of great interest globally since the introduction of light-emitting diodes (LED) and their low energy consumption as reflected in [37][38][39][40][41], thus the strong relationship with "energy efficiency" is expected. This cluster groups "lighting", "engineering research" and "light emitting diodes", with "light sources", "color", "luminance", "spectral power distribution", and "color rendering".…”

Section: Abstract Network Analysismentioning

confidence: 99%

Which Building Services Are Considered to Have Impact on Climate Change?

Veréz

Cabeza

2021

Energies

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The building sector, as a major energy consumer with high direct and indirect CO2 emissions, plays a vital role in the fight against climate change. In order to make buildings more comfortable, functional, efficient and safe, building services are used. Therefore, building services are the key to decrease their contribution to climate change. Due to the lack of organized literature on this topic, this paper presents the first comprehensive assessment of trends in the literature on building services related to climate change, which was completed by conducting a bibliometric analysis of the existing literature on the topic. The ultimate goal is to provide a source where researchers and other interested parties can find this information in an organized manner. Results show that the most abundant and recent studies related to building services are based on improving energy efficiency by optimizing systems such as ventilation or lighting, the latter with the installation of LED lights. In addition, recent studies have focused on social factors such as housing and urban growth.

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“…Touchscreens are technical devices in which, for example, plastics, adhesives or organic light-emitting diodes (OLEDs) are used. All these materials can degrade under UV irradiation and change their physical properties for the worse [ 32 ], [ 33 ], [ 34 ], [ 35 ], [ 36 ], [ 37 ], [ 38 ], [ 39 ], [ 40 ]. Lastly, it should be mentioned that shorter irradiation durations are usually achieved faster and are more environmentally friendly, as less energy and fewer UVC lamps with toxic mercury are required.…”

Section: Introductionmentioning

confidence: 99%

Review of microbial touchscreen contamination for the determination of reasonable ultraviolet disinfection doses

Heßling

Haag

Sicks

2021

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Background: Touchscreens are usually microbially contaminated and can therefore act as fomites inside and outside healthcare environments. Due to the increasing use of such touchscreens and the growing awareness of infection risks, approaches that allow safe and automatic disinfection are desired. Ultraviolet (UV) irradiation, with its known antimicrobial efficacy, could achieve this goal, but should be executed with limited touchscreen degradation, disinfection duration, and energy consumption. It should also pose as little harm as possible to humans even in case of failure. Materials and methods: A literature search was performed first to identify the microorganisms most commonly found on touchscreens. Then, the 90% reduction doses (D90 doses) for the different relevant microorganisms and UV spectral ranges were determined from the literature, and irradiation doses are suggested that should reduce most of these important microorganisms by 5 log-levels. Results: The most frequent microorganisms are staphylococci, bacilli, micrococci, enterococci, pseudomonads and E. coli with small differences between hospital and community environments, if antibiotic resistance properties are ignored. The determined irradiation doses for a 5 log-reduction of the most frequent microorganisms are about 40 mJ/cm 2 , 80 J/cm 2 , 500 J/cm 2 and 50 mJ/cm 2 for the UV spectral ranges UVC, UVB, UVA and far-UVC, respectively. These doses are also sufficient to inactivate all nosocomial ESKAPE pathogens on touchscreens by at least 99.999%. Conclusion: Disinfection is achievable in all UV spectral ranges, with UVC being the most effective, enabling automatic disinfection within a minute or less. The much higher doses required in the UVB and UVA spectral range result in much longer disinfection durations, with the advantage of a reduced risk to humans. For all kinds of UV irradiation, the doses should be limited to reasonable values to avoid irradiating an already more or less sterile surface and to prevent degradation of touchscreen devices.

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Accelerated ageing of organic LED panels using ultraviolet exposure

Cited by 3 publications

References 13 publications

Degradation of OLED performance by exposure to UV irradiation

Degradation of OLED performance by exposure to UV irradiation

Which Building Services Are Considered to Have Impact on Climate Change?

Review of microbial touchscreen contamination for the determination of reasonable ultraviolet disinfection doses

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