Organic light-emitting diodes with split recombination zones: A concept for versatile color tuning

Overcoming Challenges in OLED Technology for Lighting Solutions

“…As for the characteristics of light, OLEDs emit a softly diffused light that replicates natural daylight, resembling the warmth of traditional incandescent lamps and contributing to creating a visually comfortable ambiance, with the additional benefit of energy efficiency [15,16]. The panels can also be transparent when turned off and offer the capacity for color tunability [17,18]. In addition, the fabrication techniques are compatible with flexible substrates requiring low temperatures; besides glass or metal substrates, OLEDs can be deposited on thin plastic sheets, ceramics, and fabrics, adding a further innovative aspect of versatility [19][20][21].…”

Solid-State Lighting Using Side-by-Side White Phosphorescent Organic Light-Emitting Diodes

“…Recent studies have shown that the quality of environmental lighting can affect room aesthetics as well as psychological functioning, such as moods. , This suggests a need for lighting sources that can fit a broad and varying range of requirements. The use of white organic light-emitting diodes (WOLEDs) for solid-state lighting has increased significantly in recent years as a result of their desirable form factors, high efficiencies, long operational lifetimes, color versatility, and other features. − Illumination sources utilizing organic emitters offer diffuse light that can cover large areas and are flexible and transparent. , Materials and device design further enable a range of aesthetic qualities, including a high color-rendering index (CRI) and color temperature tunability, without sacrificing efficiency. − Previous work using a stacked WOLED geometry consisting of multiple emissive layers has achieved efficient white light and a CRI as high as 89. , Stacked WOLEDs comprising individually contacted red, green, and blue, or blue and yellow sub-elements allow for independent tuning of both emission color and intensity, although this architecture presents challenges in contacting metal electrodes within the organic stack. − Color tunability has also been achieved in devices where emission color is dependent on applied voltage. , To generate the desired colors, high voltage or alternating current may be required. A side-by-side (S×S) geometry, in which two or three separately energized monochromatic emitter stripes are horizontally positioned relative to one another, enables color tunability under normal device operating conditions, while also affording the possibility of 100% internal efficiency when triplet-controlled emitting molecules are employed in the individual color elements. − …”