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Special Issue "Organic Light Emitting Diodes II"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: 31 July 2019

Special Issue Editor

Guest Editor
Prof. Dr. Jwo-Huei Jou

Department of Materials Science and Engineering, National Tsing Hua University, Hsin-chu, Taiwan
Website | E-Mail
Interests: high-efficiency; long lifetime; natural-light-style and omni friendly organic light emitting diodes (OLEDs)

Special Issue Information

Dear Colleagues,

Organic light-emitting diodes (OLEDs) are disrupting the display and lighting markets, thanks to their notable characteristics, such as being planar, soft, transparent, fully dimmable, flexible, spectrum tailorable, natural light-style, human-friendly, energy saving, etc. Increasing scientific and technological efforts have been made, not only to stimulate commercialization, but also provide better display and illumination products to the world. Still, there are more blanks to fill with a more competitive OLED technology from lighting perspectives. Hence, we are hoping to publish a Special Issue to gather significant contributions from OLED researchers and experts. This Special Issue aims to offer a platform for latest design strategy of organic molecules, synthesis processes, fabrication routes of OLED devices, and approaches for high efficiency. Manuscripts may be, but are not limited to, the following topics: Efficient OLED materials, efficient OLED devices, the status of white light or monochromes in PM-OLES, AM-OLED, and OLEDs for signage, tandem OLEDs, PIN OLEDs, blue OLEDs, transparent OLEDs, transparent/flexible/wearable OLEDs, printable OLEDs, approaches for long lifetime OELDs, etc.

Prof. Jwo-Huei Jou
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Designing and synthesis of efficient organic molecules
  • TADF materials
  • Approaches of fabricating highly efficient and long lifespan OLED
  • Flexible and wearable OLEDs
  • Designing and fabrication of natural-light style organic light emitting diodes
  • Transparent and conductive oxide material as an efficient anode
  • Current status of OLED display and lighting panels
  • Light extraction techniques
  • Advanced exciplex systems

Published Papers (6 papers)

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Research

Jump to: Review

Open AccessArticle White Light-Emitting Devices Based on Inorganic Perovskite and Organic Materials
Molecules 2019, 24(4), 800; https://doi.org/10.3390/molecules24040800 (registering DOI)
Received: 18 January 2019 / Revised: 17 February 2019 / Accepted: 19 February 2019 / Published: 22 February 2019
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Abstract
Perovskite-based materials have attracted considerable attention in photoelectric devices. In this paper, we report the one-step fabrication of spin-coated CsPbBr2.5I0.5 perovskite films doped with PAN (polyacrylonitrile) polymer. A red perovskite LED (PeLED) composite film was fabricated which featured a maximum [...] Read more.
Perovskite-based materials have attracted considerable attention in photoelectric devices. In this paper, we report the one-step fabrication of spin-coated CsPbBr2.5I0.5 perovskite films doped with PAN (polyacrylonitrile) polymer. A red perovskite LED (PeLED) composite film was fabricated which featured a maximum luminance value of 657 cd/m2 at 8 V. We fabricated white PeLEDs by combining hole transporting layer material emission, perovskite–polymer composite material PAN:CsPbBr2.5I0.5, and pure inorganic perovskite CsPbBr3 as a luminescent layer. The maximum luminance of the device was 360 cd/m2 at 7 V, and the color coordinate was (0.31, 0.36). We obtained an ideal white light-emitting device that paves the way for further development of white PeLEDs. Full article
(This article belongs to the Special Issue Organic Light Emitting Diodes II)
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Open AccessArticle Effect of Host Moieties on the Phosphorescent Spectrum of Green Platinum Complex
Molecules 2019, 24(3), 454; https://doi.org/10.3390/molecules24030454
Received: 28 December 2018 / Revised: 23 January 2019 / Accepted: 26 January 2019 / Published: 28 January 2019
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Abstract
Highly efficient, operationally stable, and pure-color organic light-emitting diodes (OLEDs) are of considerable significance for developing practical wide-color-gamut displays. Further, we have demonstrated the feasibility of an efficient pure green phosphorescent OLED (PHOLED) by employing a narrow-band platinum complex and a top-emitting structure. [...] Read more.
Highly efficient, operationally stable, and pure-color organic light-emitting diodes (OLEDs) are of considerable significance for developing practical wide-color-gamut displays. Further, we have demonstrated the feasibility of an efficient pure green phosphorescent OLED (PHOLED) by employing a narrow-band platinum complex and a top-emitting structure. The utilization of the thermally activated delayed fluorescence (TADF) material as the phosphorescent host is expected to serve as a promising solution for obtaining operationally stable PHOLEDs with high color purity. However, the emission spectrum of the platinum complex in the TADF host exhibits a considerably broad emission spectrum. This study investigates the cause of the spectral change by evaluating the photoluminescence spectra of the platinum complex in various hosts exhibiting different molecular structures. The triazine unit in the host material was observed to result in exciplex formation between the lowest unoccupied molecular orbital (LUMO) of the host and the highest occupied molecular orbital (HOMO) of the platinum complex. Therefore, the TADF material that sterically hinders the triazine unit is considered to be suitable to prevent both exciplex formation and spectral broadening. Full article
(This article belongs to the Special Issue Organic Light Emitting Diodes II)
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Graphical abstract

Open AccessArticle Deep-Blue and Hybrid-White Organic Light Emitting Diodes Based on a Twisting Carbazole-Benzofuro[2,3-b]Pyrazine Fluorescent Emitter
Molecules 2019, 24(2), 353; https://doi.org/10.3390/molecules24020353
Received: 24 December 2018 / Revised: 12 January 2019 / Accepted: 13 January 2019 / Published: 19 January 2019
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Abstract
A novel deep-blue fluorescent emitter was designed and synthesized. The external quantum efficiency (ηEQE) of the blue-emitting, doped, organic light-emitting diode (OLED) was as high as 4.34%. The device also exhibited an excellent color purity with Commission Internationale de l’Eclairage (CIE) [...] Read more.
A novel deep-blue fluorescent emitter was designed and synthesized. The external quantum efficiency (ηEQE) of the blue-emitting, doped, organic light-emitting diode (OLED) was as high as 4.34%. The device also exhibited an excellent color purity with Commission Internationale de l’Eclairage (CIE) coordinates of x = 0.15 and y = 0.05. In addition, the triplet energy had a value of 2.7 eV, which is rare for an emitter with deep-blue emission, which makes it a preferred choice for high-performance white OLEDs. By optimizing the device architectures, the color of hybrid-white OLEDs could be tunable from warm white to cool white using the aforementioned material as a bifunctional material. That is, the ηEQE of the hybrid warm-white OLED is 20.1% with a CIE x and y of 0.46 and 0.48 and the ηEQE of the hybrid cool-white OLED is 9% with a CIE x and y of 0.34 and 0.33. Full article
(This article belongs to the Special Issue Organic Light Emitting Diodes II)
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Open AccessArticle Reduced Efficiency Roll-Off in White Phosphorescent Organic Light-Emitting Diodes Based on Double Emission Layers
Molecules 2019, 24(1), 211; https://doi.org/10.3390/molecules24010211
Received: 12 December 2018 / Revised: 2 January 2019 / Accepted: 5 January 2019 / Published: 8 January 2019
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Abstract
We demonstrate high-efficiency white phosphorescent organic light-emitting diodes with low efficiency roll-off. The feature of the device concept is employing two phosphorescent emission layers (EMLs) separated by a mixed interlayer. Both the EMLs are doped by two phosphorescent dyes. The resulting white device [...] Read more.
We demonstrate high-efficiency white phosphorescent organic light-emitting diodes with low efficiency roll-off. The feature of the device concept is employing two phosphorescent emission layers (EMLs) separated by a mixed interlayer. Both the EMLs are doped by two phosphorescent dyes. The resulting white device with the optimized doping concentration shows a maximum efficiency of 31.0 cd/A with extremely low efficiency roll-off of 30.7 cd/A at 1000 cd/m2, 27.2 cd/A at 5000 cd/m2, and 25.5 cd/A at 10,000 cd/m2, respectively, without any outcoupling structures. This is enabled by the balanced charge carrier transport in EMLs, leading to broader exciton recombination zone. Full article
(This article belongs to the Special Issue Organic Light Emitting Diodes II)
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Open AccessArticle Organic Fluorescent Compounds that Display Efficient Aggregation-Induced Emission Enhancement and Intramolecular Charge Transfer
Molecules 2018, 23(6), 1446; https://doi.org/10.3390/molecules23061446
Received: 29 May 2018 / Revised: 8 June 2018 / Accepted: 8 June 2018 / Published: 14 June 2018
PDF Full-text (1613 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A series of symmetric sulfone-linked organic fluorescent compounds (1ac) was synthesized and characterized. V-shaped 1ac were designed as aggregate of intramolecular charge transfer (ICT) and aggregation-induced emission enhancement (AIEE) processes. The 1ac emitted intense blue [...] Read more.
A series of symmetric sulfone-linked organic fluorescent compounds (1ac) was synthesized and characterized. V-shaped 1ac were designed as aggregate of intramolecular charge transfer (ICT) and aggregation-induced emission enhancement (AIEE) processes. The 1ac emitted intense blue violet lights in normal solvents. A large red shift of the emission wavelength and dramatic decrease of emission efficiency occurred with increasing solvent polarity. The 1ac will function well as electron transport and blue light-emitting materials through theoretical calculations. Full article
(This article belongs to the Special Issue Organic Light Emitting Diodes II)
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Review

Jump to: Research

Open AccessReview Recent Developments in Tandem White Organic Light-Emitting Diodes
Molecules 2019, 24(1), 151; https://doi.org/10.3390/molecules24010151
Received: 7 December 2018 / Revised: 24 December 2018 / Accepted: 25 December 2018 / Published: 2 January 2019
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Abstract
Tandem white organic light-emitting diodes (WOLEDs) are promising for the lighting and displays field since their current efficiency, external quantum efficiency and lifetime can be strikingly enhanced compared with single-unit devices. In this invited review, we have firstly described fundamental concepts of tandem [...] Read more.
Tandem white organic light-emitting diodes (WOLEDs) are promising for the lighting and displays field since their current efficiency, external quantum efficiency and lifetime can be strikingly enhanced compared with single-unit devices. In this invited review, we have firstly described fundamental concepts of tandem device architectures and their use in WOLEDs. Then, we have summarized the state-of-the-art strategies to achieve high-performance tandem WOLEDs in recent years. Specifically, we have highlighted the developments in the four types of tandem WOLEDs (i.e., tandem fluorescent WOLEDs, tandem phosphorescent WOLEDs, tandem thermally activated delayed fluorescent WOLEDs, and tandem hybrid WOLEDs). Furthermore, we have introduced doping-free tandem WOLEDs. In the end, we have given an outlook for the future development of tandem WOLEDs. Full article
(This article belongs to the Special Issue Organic Light Emitting Diodes II)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

1. Author: Yukiko Iwasaki
Tentative title: Effect of Host Substituents on the Color Purity of Green PHOLED using Platinum Complex Emitter
Tentative abstract: Highly efficient, operationally stable and pure-color organic light-emitting diodes (OLEDs) are of great significance for practical wide-color-gamut displays. In recent years, emitters achieving high color purity have been obtained by employing a planar and rigid molecular structure. We have demonstrated that an efficient pure green phosphorescent OLED (PHOLED) by employing both a platinum complex and a top-emitting structure. Toward the development of pure green PHOLEDs with high operational stability, it is essential to clarify the effect of host materials on the emission spectrum of the platinum complex. This is because the emission spectrum of the platinum complex in a TADF material exhibits a considerably broad emission spectrum, although TADF materials have been reported to be suitable hosts for efficient and stable PHOLEDs. In this study, we investigated the origin of this spectral change by evaluating the photoluminescence of a platinum complex in several hosts with different substituents. From these results, we discuss the design strategy of host materials suitable for maintaining the spectrum shape of platinum complex.

2. Author: Yu Duan

Affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science & Engineering,  Jilin University, Changchun 130012, P. R. China

Title:white light-emitting devices based on perovskite and organic materials via evaporation technology

Abstract:As a new type of photoelectric material, perovskite material has the advantages of high crystallinity, high carrier mobility, low exciton binding energy, high quantum efficiency, wide absorption spectrum and solution process ability. These advantages make perovskite materials are widely used in thin film solar cells and electroluminescent devices, and have attracted much attention in the field of materials research.In this paper, We doped polymer PAN into CsPbBr2.5I0.5 perovskite precursor solution, and high coverage and average PAN: CsPbBr2.5I0.5 mixed films were obtained by one-step spin-coating method. And we prepared a red perovskite device with the mixed film as the light-emitting layer (the EL peak intensity is located at 680 nm), and the device structure is ITO/Pedot:PSS/PAN:CsPbBr2.5I0.5/TPBi/Liq/Al. The device reached a maximum luminance of 657 cd/m2 at 8V. At the same time, we prepared white PeLED with blue organic material NPB and inorganic perovskite materials CsPbBr2.5I0.5,CsPbBr3 as the light-emitting layer. The device structure is ITO/Pedot:PSS/CsPbBr2.5I0.5/NPB/CsPbBr3/TPBi/Liq/Al, the maximum luminance of the device is 360cd/m2 at 7V,the current efficiency is 0.2cd/A, and the color coordinate of PeLED is (0.31, 0.36). We obtained a ideal white emission, which provides a feasible idea for the development of white perovskite light-emitting devices.

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