Efficient multilayer and single layer phosphorescent organic light-emitting devices using a host with balanced bipolar transporting properties and appropriate energy level

Zang, Chun-Xiu; Peng, Xiaomei; Wang, Hui; Yu, Ziwei; Zhang, Letian; Zhao, Hongyu

doi:10.1016/j.orgel.2017.07.034

Cited by 14 publications

(6 citation statements)

References 42 publications

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“…This modification should impact the HOMO energy level and the hole mobility but should maintain the other properties and particularly the thermal stability. In the field of OLEDs, the widely known electron-rich phenylacridine unit (PA) , used in SPA-2,7-F(POPh 2 ) 2 holds a special place as it is one of the most efficient building units due to its excellent charges injection/transport properties. ,,, This fragment has been, in recent years, a fantastic playground for organic chemists, which have designed other structurally related fragment, named IndoloAcridine (IA), ,, QuinolinoPhenoThiaZine (QPTZ), , and QuinolinoAcridine (QA) , (Figure ), which all display specific electronic properties. In these new hosts, the two phenyl rings of the PA backbone are connected in a different manner, and all the properties originate from this structural feature.…”

Section: Modification Of the Electron-rich Unit (Phenylacridine-like ...mentioning

confidence: 99%

Donor-Spiro-Acceptor Molecular Design: A Key toward High-Efficiency Simplified Single-Layer Phosphorescent Organic Light-Emitting Diodes

Poriel,

Rault-Berthelot

2023

Acc. Mater. Res.

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Conspectus In organic electronic technologies, Single-Layer Phosphorescent Organic Light-Emitting Diodes (SL-PhOLEDs), made of only the electrodes and the Emissive Layer (EML), are a new generation of simplified PhOLEDs. In the field of the OLED, such a type of device has been studied for a long time as they represent “ideal” devices. Indeed, simplifying the classical multilayer structure of PhOLEDs (called ML-PhOLEDs) is important to reduce the amount of commodities, the manufacture complexity, and the production and recycling costs. However, removing the functional organic blocking/transporting layers of an ML-PhOLED stack leads to an intense decrease in the PhOLED performance. This is the main problem; the researchers have faced in this field. To keep a high performance without the different organic layers, the effective injection, transport, and recombination of charges in the device should be performed by the EML and more particularly by the host materials. This host material should then display a set of electronic and physical properties, essential to reach a high-efficiency SL-PhOLED. However, reaching high-performance SL-PhOLED is far more difficult than for ML-PhOLED and each molecular parameter of the host can dramatically decrease the PhOLED performance. The molecular design of the host is then crucial and a specific design has been particularly studied in the last years, which consists of linking an electron-rich unit to an electron-poor unit via a spiro linkage. This design called Donor-Spiro-Acceptor (D-Spiro-A) allows one to gather all the required properties in a single host and has allowed, in the past few years, important advances in the field. Nowadays, the most efficient SL-PhOLEDs use this molecular design and our group has particularly contributed to this research field. Thus, as the D-Spiro-A molecular design nowadays provides SL-PhOLEDs with the highest performance, a good understanding of its impact in the device efficiencies appears particularly important. This is the story we want to tell herein. In this Account, we discuss through a structure/properties/device performance relationship study (triplet state energy level, HOMO/LUMO energy levels, charge carriers mobilities, thermal and morphological properties, and device performances), the recent advances made by this design in the field of SL-PhOLEDs. This Account will mainly focus on the association of phenylacridine-like fragments (namely, phenylacridine, indoloacridine, quinolinophenothiazine, and quinolinoacridine) as the electron-rich unit and fluorene/phosphine oxide as the electron-poor unit, which is, in the light of the literature, the combination that has allowed the most important advances in the last years. Trying to unravel why this design has led to high performance appears to be important for the future of SL-PhOLED technology and may lead to new directions in terms of molecular design.

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Section: Modification Of the Electron-rich Unit (Phenylacridine-like ...mentioning

confidence: 99%

Donor-Spiro-Acceptor Molecular Design: A Key toward High-Efficiency Simplified Single-Layer Phosphorescent Organic Light-Emitting Diodes

Poriel,

Rault-Berthelot

2023

Acc. Mater. Res.

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“…Avec la même structure de diode, PEDOT:PSS comme HIL et LiF comme EIL, les performances de D16-D19, montrent que la matrice H2 (D16) est la mieux adaptée au dopant Ir(ppy)3. H2 (ET : 2.76 eV) [65], H9 (ET : 2.74 eV) [70] et H10 (ET : 2.78 eV) [71] ont un ET supérieur à celui de H11 (ET : 2.64 eV) [71] assurant un bon transfert d'énergie T H 1 → T G 1. La meilleure performance de D16 par rapport à D18 en terme d'EQE et de Von provient de la différence des niveaux HOMO/LUMO de ces deux SCOs, en effet, l'injection des charges est plus facile à la fois à l'anode et à la cathode dans H2 (HOMO/LUMO de -5.40/-2.46 eV) que dans H10 (HOMO/LUMO : -6.0/-2.10 eV).…”

Section: Emission Verte Des Oleds Phosphorescentesunclassified

“…Les performances de D18 et D19 sont identiques (EQE : 13.3/13.2 %) avec toutefois un Von plus faible (2.4 V vs 3.3 V) pour D19 que pour D18 signant l'injection plus facile des charges dans H11 que dans H10. H2 possède, comparé à H9, un ET similaire (2.74 vs 2.76 eV) mais une HOMO plus profonde (-5.71 vs -5.40 eV) rendant l'injection des trous plus difficiles dans D17[70] que dans D16[65]. L'injection plus difficile entraine une augmentation du Von (3.4 vs 2.3 eV) et une baisse d'EQE (14.6 vs 15.6 %).…”

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“…Les trois dopants phosphorescents rouges utilisés dans les diodes D29-D35[56,70,82,85,86] ont un ET de l'ordre de 2.0 eV et peuvent donc doper des matrices possédant des ET encore moins élevés que les matrices utilisées pour le bleu, le vert et le jaune/orange (Figure8). Avec une structure de dispositif monocouche similaire et un même dopant phosphorescent rouge bis(2méthyldibenzo[f,h]quinoxaline)(acétylacétonate) iridium(III), Ir(MDQ)2(acac), D29 et D30[70] montrent des performances similaires avec un EQE proche de 15% (Tableau 5). Malgré un niveau ET plus élevé et un écart HOMO/LUMO moins large pour H21 que pour H20, les performances des PhOLEDs sont les mêmes mettant en exergue la difficulté de concevoir des matériaux hôtes pour PhOLEDs.…”

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Diodes électroluminescentes organiques : quatre technologies différentes

Rault‐Berthelot¹,

Poriel²

2021

Optique Photonique

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Les diodes organiques électroluminescentes (OLEDs) sont des dispositifs électroniques capables d'émettre de la lumière sous l'effet d'un champ électrique. L'architecture de base d'une OLED consiste en un film mince émetteur de lumière (EML) déposé entre deux électrodes. Aujourd'hui, il existe 4 générations d'OLEDs différenciées par le processus photo-physique conduisant à l'émission de la lumière : l'OLED «fluorescente», l'OLED «phosphorescente», l'OLED «TADF» et l'OLED «hyperfluorescente». Cet article présente les 4 générations d'OLEDs pour lesquelles le mécanisme d'émission de lumière sera discuté à la lumière d'exemples sélectionnés dans la littérature.

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“…Phosphorescent OLEDs (PhOLEDs) represent an effective way to obtain advanced performance due to their intrinsic property of harvesting both singlet and triplet excitons, attaining maximum internal quantum efficiency of nearly 100% [6][7][8][9][10]. Generally speaking, in order to realize excellent performance, one universal strategy is the adoption of the multilayer structures which include carriers transport layers, exciton blocking layers, or extra space-layers to eliminate exciton quenching and balance charge carriers [11].…”

Section: Introductionmentioning

confidence: 99%

Highly Efficient Single-Layer Phosphorescent Organic Light-Emitting Diodes Based on Co-Host Structure

Zhang

Sheng

et al. 2020

Materials

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High-efficiency single-layer organic light-emitting diodes (OLEDs) based on a simple structure doped with iridium(III) bis(4-phenylthieno[3,2-c]pyridinato-N,C2′) acetylacetonate (PO-01) as emission dyes are realized, achieving maximum current efficiency (CE) and power efficiency (PE) of 37.1 cd A−1 and 33.3 lm W−1 as well as low turn-on voltage of 3.31 V. Such superior performance is mainly attributed to the employment of a uniform co-host structure and assisted charge transport property of phosphors dyes, which were in favor of the balance of charge carrier injection and transport in the single emitting layer (EML). Moreover, systematic researches on the position of exciton recombination region and the dopant effect on charge carriers were subsequently performed to better understand the operational mechanism. It could be experimentally found that the orange emitting dopants promoted the acceleration of the charge carriers transport and raised the exciton recombination efficiency, eventually leading to an excellent performance of single-layer OLEDs.

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Efficient multilayer and single layer phosphorescent organic light-emitting devices using a host with balanced bipolar transporting properties and appropriate energy level

Cited by 14 publications

References 42 publications

Donor-Spiro-Acceptor Molecular Design: A Key toward High-Efficiency Simplified Single-Layer Phosphorescent Organic Light-Emitting Diodes

Donor-Spiro-Acceptor Molecular Design: A Key toward High-Efficiency Simplified Single-Layer Phosphorescent Organic Light-Emitting Diodes

Diodes électroluminescentes organiques : quatre technologies différentes

Highly Efficient Single-Layer Phosphorescent Organic Light-Emitting Diodes Based on Co-Host Structure

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