ITO-free large-area top-emission organic light-emitting diode by blade coating

Chang, Hsien‐Ming; Meng, Hsin‐Fei; Horng, Sheng Fu; Zan, Hsiao‐Wen

doi:10.1016/j.synthmet.2015.11.025

Cited by 6 publications

(6 citation statements)

References 29 publications

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“…PEDOT: PSS film has good conductivity, so some of the holes can still be injected into the emitting layer to make the device emit light slightly, as shown in Figure 5(b). The thermal vacuum evaporation technique can control the MoO 3 thickness to 1-5 nm for optimal hole injection from MoO 3 into NPB (high current density and high luminance) [8,12,14,16]. MoO 3 behaves as an anode buffer in the OLEDs [17,18].…”

Section: Resultsmentioning

confidence: 99%

“…To reduce this energy barrier to increase the number of holes injected into the emitting layer by the anode, another layer of MoO 3 (HOMO 5.3 eV) is deposited on top of the anode Ag metal, and the energy barrier between MoO 3 /NPB HOMO is only about 0.2 eV, which is expected to enhance the hole injection amount. Many experts and researchers have used MoO 3 as a HIL or anode buffer layer for top emission OLED (TEOLED) [8,12,[14][15][16][17][18][19]. The structure of the TE-OLED is PEN/MDSN/Ag (80 nm)/MoO 3 (x nm)/NPB (35 nm)/Alq 3 (65 nm)/LiF (0.8 nm)/Al (15 nm).…”

Section: Resultsmentioning

confidence: 99%

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The Selection of Anode and Cathode Materials for Top Emission Organic Light-Emitting Diodes

Juang

Patel

Huang

et al. 2022

International Journal of Photoenergy

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In this study top emission organic light-emitting diodes (TE-OLED) were successfully fabricated on flexible PET/multilayer disordered silver nanonetwork (MDSN) substrate with conventional LiF/Al as a semitransparent cathode and Ag as a reflective anode. The effects of the hole injection layer, anode buffer layer, and an electron injection layer on the luminescence characteristics of TE-OLEDs were investigated. At first, the thickness of cathode Al is adjusted based upon the overall transmittance of the top-emission cathode and its conductivity. There is a high energy barrier for the hole between the work function of the anode Ag (4.2 eV) and the NPB highest occupied molecular orbital (HOMO) energy level (5.5 eV), which is not favorable for hole injection. This study tested four types of hole injection layer (HIL) materials. Finally, MoO3 was selected as an optimal HIL material, and the optimum thickness was adjusted, enabling the hole to be injected smoothly from the anode to the NPB and then to an emitting layer. The TE-OLED luminance reached 268 cd/m2. There is a high energy barrier between the work function of Ag and MoO3 HOMO (5.3 eV)—about 1.1 eV—which is still not conducive to the hole injection, so a thin layer of high work function metal Au (work function 5.1 eV) was added to the top of the anode silver, which more matches with the MoO3 energy level. It can make the hole easier to inject from the anode to MoO3 (HIL) and protect the silver from oxidation. At 8 V, the luminance is increased to 413.7 cd/m2, and the current efficiency is 0.81 cd/A. The luminance is significantly improved. An electron transport/hole blocking layer TPBi (10 nm) was added to enhance the electron transport capability and effectively block the holes with higher electron mobility and a higher HOMO energy level of TPBi. So that more holes can remain in the emitting layer and increase the chance of the electron-hole recombination to improve the luminance and current efficiency of TE-OLED. At 8 V, the luminance and current efficiency can reach 611.4 cd/m2 and 0.95 cd/A, respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The Selection of Anode and Cathode Materials for Top Emission Organic Light-Emitting Diodes

Juang

Patel

Huang

et al. 2022

International Journal of Photoenergy

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“…This advantage stems from a rapid drying process and is highly beneficial for fabricating multilayer OLEDs based on those materials with a limited solubility window, which usually suffer from solvent orthogonality issues in solution deposition. 118 For example, Tseng et al 115 presented multilayer PLEDs using blade coating on a hot plate. Such methods enabled negligible film thickness variations (i.e., 3.3% on a 10 cm scale) as well as low film roughness (i.e., ∼0.3 nm on the micrometer scale).…”

Section: Blade Coatingmentioning

confidence: 99%

Printable organic light-emitting diodes for next-generation visible light communications: a review

et al. 2023

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Visible light communication (VLC) is an emerging technology employing light-emitting diodes (LEDs) to provide illumination and wireless data transmission simultaneously. Harnessing cost-efficient printable organic LEDs (OLEDs) as environmentally friendly transmitters in VLC systems is extremely attractive for future applications in spectroscopy, the internet of things, sensing, and optical ranging in general. Here, we summarize the latest research progress on emerging semiconductor materials for LED sources in VLC, and highlight that OLEDs based on nontoxic and cost-efficient organic semiconductors have great opportunities for optical communication. We further examine efforts to achieve high-performance white OLEDs for general lighting, and, in particular, focus on the research status and opportunities for OLED-based VLC. Different solution-processable fabrication and printing strategies to develop high-performance OLEDs are also discussed. Finally, an outlook on future challenges and potential prospects of the next-generation organic VLC is provided.

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“…1−6 Furthermore, and in contrast to their inorganic counterpart, OLEDs enable the production of large-area flat panel lighting systems without any light distribution elements. 7,8 In principle, an OLED consists of an organic electroluminescent material sandwiched between two electrodes. Additional electron-and hole-transporting layers at the anode and cathode interfaces can further improve charge carrier injection and thus enhance the overall device performance.…”

mentioning

confidence: 99%

“…Organic light emitting diodes (OLEDs) show a huge potential to be the next-generation light source, as they are thinner, more eco-friendly with respect to energy consumption and materials, easier to fabricate due to solution processability, not restricted to any shape, and more flexible or even stretchable and provide wider viewing angles than the present lighting systems. − Furthermore, and in contrast to their inorganic counterpart, OLEDs enable the production of large-area flat panel lighting systems without any light distribution elements. , In principle, an OLED consists of an organic electroluminescent material sandwiched between two electrodes. Additional electron- and hole-transporting layers at the anode and cathode interfaces can further improve charge carrier injection and thus enhance the overall device performance.…”

mentioning

confidence: 99%

Semitransparent Organic Light Emitting Diodes with Bidirectionally Controlled Emission

et al. 2016

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Semitransparent OLEDs are a candidate for large-area eco-friendly light sources that can be integrated into building facades, suggesting colorful windows that become luminescent if the OLED is switched on. However, since the light is emitted in two directions, smart light engineering has to be implemented to direct the light into a preferred direction and to prevent for instance huge energetic losses to the outside of a building. We introduce an unprecedented device architecture, composed of a dielectric mirror attached to a semitransparent OLED. Such a system features a dual functionality that depends on the viewing direction: changing the color perception and/or enhancing the light directionality while still preserving a high overall device transparency. First, we motivate the potential of this concept with a theoretical study, showing that broad modifications in the color range can be realized via device optimization and that the maximum possible emission enhancement of the OLED is limited only by the transparency of the interfacial layers and the electrodes. Then, experimental investigations with a semitransparent yellow OLED (transparency = 58.2%) in combination with six different dielectric mirrors validate the theoretical results. Retaining the same color perception, up to 80% of the total emitted light can be directed toward one side while the color is modified at the other side of the device stack. Here, modifications from yellow to purple to dark or light blue can be realized.

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ITO-free large-area top-emission organic light-emitting diode by blade coating

Cited by 6 publications

References 29 publications

The Selection of Anode and Cathode Materials for Top Emission Organic Light-Emitting Diodes

The Selection of Anode and Cathode Materials for Top Emission Organic Light-Emitting Diodes

Printable organic light-emitting diodes for next-generation visible light communications: a review

Semitransparent Organic Light Emitting Diodes with Bidirectionally Controlled Emission

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