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| 1 | Adjustable white-light emission from a photo-structured micro-OLED array显示文摘White organic light-emitting diodes(OLEDs)are promising candidates for future solid-state lighting applications and backplane illumination in large-area displays.One very specific feature of OLEDs,which is currently gaining momentum,is that they can enable tunable white light emission.This feature is conventionally realized either through the vertical stacking of independent OLEDs emitting different colors or in lateral arrangement of OLEDs.The vertical design is optically difficult to optimize and often results in efficiency compromises between the units.In contrast,the lateral concept introduces severe area losses to dark regions between the subunits,which requires a significantly larger overall device area to achieve equal brightness.Here we demonstrate a color-tunable,two-color OLED device realized by side-by-side alignment of yellow and blue p-i-n OLEDs structured down to 20μm by a simple and up-scalable orthogonal photolithography technique.This layout eliminates the problems of conventional lateral approaches by utilizing all area for light emission.The corresponding emission of the photo-patterned two-unit OLED can be tuned over a wide range from yellow to white to blue colors.The independent control of the different units allows the desired overall spectrum to be set at any given brightness level.Operated as a white light source,the microstructured OLED reaches a luminous efficacy of 13 lm W^(−1) at 1000 cd m^(−2) without an additional light outcoupling enhancement and reaches a color rendering index of 68 when operated near the color point E.Finally,we demonstrate an improved device lifetime by means of size variation of the subunits. | Simonas Krotkus Daniel Kasemann Simone Lenk Karl Leo Sebastian Reineke | 2016 | Light(Science & Applications)2016，5，1： | 2 |
| 2 | Experimental proof of Joule heating-induced switched-back regions in OLEDs显示文摘Organic light-emitting diodes(OLEDs)have become a major pixel technology in the display sector,with products spanning the entire range of current panel sizes.The ability to freely scale the active area to large and random surfaces paired with flexible substrates provides additional application scenarios for OLEDs in the general lighting,automotive,and signage sectors.These applications require higher brightness and,thus,current density operation compared to the specifications needed for general displays.As extended transparent electrodes pose a significant ohmic resistance,OLEDs suffering from Joule self-heating exhibit spatial inhomogeneities in electrical potential,current density,and hence luminance.In this article,we provide experimental proof of the theoretical prediction that OLEDs will display regions of decreasing luminance with increasing driving current.With a two-dimensional OLED model,we can conclude that these regions are switched back locally in voltage as well as current due to insufficient lateral thermal coupling.Experimentally,we demonstrate this effect in lab-scale devices and derive that it becomes more severe with increasing pixel size,which implies its significance for large-area,high-brightness use cases of OLEDs.Equally,these non-linear switching effects cannot be ignored with respect to the long-term operation and stability of OLEDs;in particular,they might be important for the understanding of sudden-death scenarios. | Anton Kirch Axel Fischer Matthias Liero Jurgen Fuhrmann Annegret Glitzky Sebastian Reineke | 2020 | Light(Science & Applications)2020，9，1： | 2 |
| 3 | Reduced effi- ciency roll-off in phosphorescent organic light emitting di- odes by suppression of triplet-triplet annihilation显示文摘 | Reineke Sebastian Schwartz Gregor | 2007 | Ap- plied Physics Letters2007，91，12： | 1 |
| 4 | Real-time beam shaping without additional optical elements显示文摘Providing artificial light and enhancing the quality of the respective light sources is of continued interest in the fields of solid state,condensed matter,and semiconductor physics.Much research has been carried out to increase the luminous efficiency,lifetime and colour stability of such devices.However,the emission characteristics of a given light source do not necessarily comply with today’s often sophisticated applications.Here,beam shaping addresses the transformation of a given light distribution into a customized form.This is typically achieved by secondary optical elements often sporting elaborate designs,where the actual light source takes up only a small fraction of the system’s volume.Such designs limit the final light source to a single permanent operation mode,which can only be overcome by employing mechanically adjustable optical elements.Here we show that organic light-emitting diodes(OLEDs)can enable real-time regulation of a beam shape without relying on secondary optical elements and without using any mechanical adjustment.For a red light-emitting two-unit OLED architecture,we demonstrate the ability to continuously tune between strongly forward and strongly sideward emission,where the device efficiency is maintained at an application-relevant level ranging between 6 and 8%of external quantum efficiency for any chosen setting.In combination with additional optical elements,customizable and tuneable systems are possible,whereby the tuning stems from the light source itself rather than from the use of secondary optics. | Felix Fries Markus Fröbel Pen Yiao Ang Simone Lenk Sebastian Reineke | 2018 | Light(Science & Applications)2018，7，1： | 0 |
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