Tunable full-color emission of two-unit stacked organic light emitting diodes with dual-metal intermediate electrode

Liang, Chunjun; Choy, Wallace C. H.

doi:10.1016/j.jorganchem.2009.03.016

Cited by 28 publications

(14 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A further refinement of the tandem device concept are devices that allow the individual subdevices within the stack to be separately addressed 60, 61. The emission color of such devices can be easily tuned by adjusting the current density in each subdevice.…”

Section: Approaches To White Light Generationmentioning

confidence: 99%

White Organic Light‐Emitting Diodes

2010

View full text Add to dashboard Cite

White organic light-emitting diodes (WOLEDs) offer a range of attractive characteristics and are in several regards conceptually different from most currently used light sources. From an application perspective, their advantages include a high power efficiency that rivals the performance of fluorescent lamps and inorganic LEDs and the potential for a very low cost of manufacturing. As flat-panel light sources they are intrinsically glare-free and generate light over a large area. WOLEDs are constantly improving in terms of performance, durability, and manufacturability, but these improvements require joint research efforts in chemistry and the materials sciences to design better materials as well as in physics and engineering to invent new device concepts and design suitable fabrication schemes, a process that has generated many exciting scientific questions and answers. This article reviews current developments in the field of WOLEDs and puts a special focus on new device concepts and on approaches to reliable and cost-efficient WOLED manufacturing.

show abstract

Section: Approaches To White Light Generationmentioning

confidence: 99%

White Organic Light‐Emitting Diodes

2010

View full text Add to dashboard Cite

show abstract

“…[ 4 ] In multilayer OLETs, separate carrier‐transport and light‐emitting layers can lead to good luminous efficiencies; [ 5 ] however, the complexity and high cost of fabricating such devices have hindered their further development. In addition to exploring miniaturized devices having simple architectures, the ability to adjust the emission spectrum and intensity of organic light‐emitting diodes (OLEDs) is also crucial to the realization of well‐controlled displays; two approaches have been adopted widely: 1) voltage‐dependent emission shifting [ 6–9 ] and 2) the stacking of tandem [ 10–18 ] multiple monochrome light‐emitting units or aligning them side‐by‐side. [ 19–21 ] Nonetheless, the brightness of a device is compromised when tuning its emission spectrum or intensity with respect to the voltage, and the complicated protocols necessary for fabricating multiple light‐emitting units pose major challenges.…”

Section: Figurementioning

confidence: 99%

Alternating‐Current‐Driven Color‐Tunable Organic Light‐Emitting Triodes

Zhao

Ali

et al. 2021

Advanced Optical Materials

View full text Add to dashboard Cite

lighting panels incorporate light-emitting units that are controlled by a separate backplane of transistors; [2] such complexity and high cost limit their large-scale implementation. The challenge exists to develop new device configurations that simultaneously offer efficient light emission and effective operational control without employing any backplane circuitry, thereby simplifying the fabrication process and lowering the cost. In this scenario, smart devices-for example, organic light-emitting transistors (OLETs) that demonstrate both electroluminescence (EL) and control functions in a single unit-have attracted the attention of both academia and industry. [3] Depending on their structures, OLETs are categorized into two general types: singlelayer and multilayer OLETs. Although single-layer OLETs typically have the preferred device architecture, because of their capability to display carrier transport and light emission from a single active layer, it is quite difficult for conventional materials and device configurations to provide both of these objectives simultaneously. [4] In multilayer OLETs, separate carrier-transport and light-emitting layers can lead to good luminous efficiencies; [5] however, the complexity and high cost of fabricating such devices have hindered their further development. In addition to exploring miniaturized devices having simple architectures, the ability to adjust the emission spectrum and intensity of organic light-emitting diodes (OLEDs) is also crucial to the realization of well-controlled displays; two approaches have been adopted widely: 1) voltage-dependent emission shifting [6][7][8][9] and 2) the stacking of tandem [10][11][12][13][14][15][16][17][18] multiple monochrome light-emitting units or aligning them side-by-side. [19][20][21] Nonetheless, the brightness of a device is compromised when tuning its emission spectrum or intensity with respect to the voltage, and the complicated protocols necessary for fabricating multiple light-emitting units pose major challenges. Considering the aforementioned technical issues, there remains much room to explore new multifunctional device configurations with well-controlled operation.Current state-of-the-art lighting devices are mostly driven by direct current (DC) and therefore require additional back-end electronics (e.g., power converters and rectifiers) while integrating into household electric systems that typically comprise Exploring multifunctional, miniaturized light-emitting devices with well-controlled operation is deemed vital to meet the increasing demands of full-color displays and lighting systems. Nevertheless, complicated architectures, low performance, and poor operational control remain daunting challenges in the realization of smart devices. Here, an alternating-current-driven organic light-emitting triode (AC-OLETr) is reported with simple yet versatile architecture that emits light with precise control over the color and intensity. The fabricated AC-OLETr devices are driven and regulated by a three-phase AC supp...

show abstract

“…In contrast to the majority of publications on this topic, our devices are driven by an alternating current (AC) signal, which allows us to reduce the required number of independently addressable electrodes from three to only two. 8,[16][17][18] By using an ultrathin and highly transparent layer of highly conductive metal as the intermediate electrode, [19][20][21] our devices achieve efficiencies comparable to those of state-of-the-art non-color-tunable white OLEDs with the additional advantage of providing continuous color tuning at constant brightness from deep blue through cold-white and warm-white to saturated yellow. Our device efficiencies of up to 36.8 lm W 21 at warm-white color coordinates are-to the best of our knowledge-the highest values achieved thus far for any freely color-tunable white OLED.…”

Section: Introductionmentioning

confidence: 98%

Get it white: color-tunable AC/DC OLEDs

et al. 2015

View full text Add to dashboard Cite

Organic light-emitting diodes (OLEDs) have gained considerable attention because of their use of inherently flexible materials and their compatibility with facile roll-to-roll and printing processes. In addition to high efficiency, flexibility and transparency, reliable color tunability of solid state light sources is a desirable feature in the lighting and display industry. Here, we demonstrate a device concept for highly efficient organic light-emitting devices whose emission color can be easily adjusted from deep-blue through cold-white and warm-white to saturated yellow. Our approach exploits the different polarities of the positive and negative half-cycles of an alternating current (AC) driving signal to independently address a fluorescent blue emission unit and a phosphorescent yellow emission unit which are vertically stacked on top of each other. The electrode design is optimized for simple fabrication and driving and allows for two-terminal operation by a single source. The presented concept for color-tunable OLEDs is compatible with application requirements and versatile in terms of emitter combinations. INTRODUCTIONIn recent years, organic light-emitting diodes (OLEDs) have evolved into a mature technology and OLEDs are now used in various display applications. OLEDs provide an internal charge-to-photon conversion efficiency of nearly 100% and deliver homogeneous emission over large areas, making them promising candidates for new and innovative lighting applications. 1 White OLEDs, in particular, offer great potential for energy-efficient general illumination: luminous efficacies of more than 90 lm W 21 , comparable to the best fluorescent tubes, have already been reported. 2,3 Furthermore, OLED-based light sources can be made mechanically flexible and transparent, offering new opportunities for architecture, visual art and decoration. 4 The reliable realtime tunability of the OLED emission color would impart further momentum to OLED technology on its way to becoming a widespread source of general illumination. Thus far, two different color-tuning concepts have prevailed in the literature. One exploits voltagedependent changes in emission color and was demonstrated as early as 1994 for OLEDs fabricated from polymer blends. 5 Voltage-dependent color shifts are the result of a variety of mechanisms, e.g., voltagedependent charge trapping, a spatial shift of the recombination zone, a modified exciton distribution, or exciton quenching at high current densities. [5][6][7] However, this approach has several drawbacks: not only are the mechanisms that lead to voltage-dependent color-shifts difficult to control, but adjusting the driving voltage also unavoidably results in a dramatic and undesired change in device brightness. The second concept overcomes the disadvantages of the voltage-controlled approach by using a stacked tandem OLED structure with two (or more) independently addressable units emitting light of different colors. 8,9 In comparison with the first method, this approach provides

show abstract

Tunable full-color emission of two-unit stacked organic light emitting diodes with dual-metal intermediate electrode

Cited by 28 publications

References 19 publications

White Organic Light‐Emitting Diodes

White Organic Light‐Emitting Diodes

Alternating‐Current‐Driven Color‐Tunable Organic Light‐Emitting Triodes

Get it white: color-tunable AC/DC OLEDs

Contact Info

Product

Resources

About