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Electrostatic potential dispersing pyrimidine-5-carbonitrile acceptor for high efficiency and long lifetime thermally activated delayed fluorescence organic light-emitting diodes
摘要： Pyrimidine-5-carbonitrile was developed as an electrostatic potential managing and strong acceptor moiety of thermally activated delayed fluorescence (TADF) emitters for high efficiency and long lifetime in devices. Two types of TADF emitters with the donor moiety extended from either the 2 or 4 position of the acceptor moiety were prepared to study the effect of the donor substitution position on the TADF characteristics of the TADF emitters. Comparison of the two types of TADF emitters suggested that the extension of the donor structure from the 4 position of the pyrimidine-5-carbonitrile acceptor is an effective way of enhancing the external quantum efficiency (EQE) and lifetime of the TADF devices. A high EQE of 19.8% and lifetime exceeding that of the state-of-the-art green TADF emitter were demonstrated using one of the pyrimidine-5-carbonitrile derived emitters through the uniformly distributed electrostatic potential.
关键词： organic light-emitting diodes,Pyrimidine-5-carbonitrile,thermally activated delayed fluorescence,electrostatic potential,high efficiency,long lifetime
更新于2025-09-16 10:30:52
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Optimized design of silicone pad for bended window lamination in organic light-emitting diodes
摘要： Recently, various types of displays have been developed for use in smartphones. In particular, the shape of the glass used as the cover window of a smartphone has developed from a flat shape to a vandal shape with multiple curvatures. The lamination process for bonding an OLED backplane to such a bended cover window requires a relatively high level of skill. To develop such a technique, we designed a silicone pad with sufficient adhesive strength to suit the various curvatures. In this paper, we have confirmed the results.
关键词： Lamination,Silicone,Shore hardness,Organic light-emitting diodes,Optically clear adhesive
更新于2025-09-16 10:30:52
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Blocking exciton-quenching pathways in host and guest interfaces for high performance solution-processed TADF OLEDs with external quantum efficiency approaching 25%
摘要： Although doping system can effectively reduce the concentration quenching of thermally activated delayed fluorescence emitter, the inevitable collision between host and guest may be other energy leakage pathways, which are usually ignored in the previous studies. Here, a new encapsulated molecule Cz-4CzIPN with TADF emissive core and steric shield is conveniently synthesized and fully characterized. The TADF property ensures the efficient triplet exciton utilization, while the encapsulated feature endows the adjacent molecules a big steric bulk to reduce exciton quenching. By using the encapsulated TADF materials as both host and guest, solution-processed TADF OLEDs achieved the maximum external quantum efficiency (EQE) as high as 24.3%, which is among the best results for solution-processed TADF OLEDs reported so far. However, removing any protection of host or guest, the device efficiency will be accordingly reduced. Particularly, when the host and guest are both unencapsulated, the device can only exhibits the EQEmax of 8.0%, which indicates the existence of severe exciton quenching process. This research demonstrates the molecular interface engineering is a promising strategy for blocking the exciton quenching pathways of the solution-processed doping system by suppressing the intermolecular interaction.
关键词： TADF,host-guest interfaces,solution-process,organic light emitting diodes technology
更新于2025-09-16 10:30:52
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Oxadiazole derivatives as bipolar host materials for high-performance blue and green phosphorescent organic light-emitting diodes
摘要： By combining two n-type groups, pyridine and oxadiazole, with one p-type carbazole group, two novel bipolar hosts, namely 2-(3-(9H-carbazol-9-yl)-[1,10-biphenyl]-3-yl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (PyOxd-mCz) and 2-(40-(9H-carbazol-9-yl)-[1,10-biphenyl]-3-yl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (PyOxd-pCz) have been developed as hosts for blue and green phosphorescent organic light-emitting diodes (PhOLEDs). The two compounds exhibit similar HOMO levels of ?5.64 eV for PyOxd-mCz and ?5.63 eV for PyOxd-pCz and the same LUMO level of ?2.60 eV. With a more twisted configuration due to meta connections, PyOxd-mCz possesses a higher triplet energy level (ET = 2.77 eV) and more balanced carrier transport than PyOxd-pCz (ET = 2.60 eV). PyOxd-mCz hosted devices achieve a peak current efficiency of 39.7 cd A?1 and a maximum EQE of 20.8% with a low turn-on voltage of 3.5 V for FIrpic and 55.2 cd A?1 and 16.4% for Ir(ppy)3. Apart from the appropriate frontier molecular orbital levels and sufficiently high triplet energy of PyOxd-mCz, the more balanced carrier transport plays a key role for excellent device performance.
关键词： phosphorescent organic light-emitting diodes,bipolar host materials,blue and green PhOLEDs,PyOxd-mCz,PyOxd-pCz
更新于2025-09-16 10:30:52
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Achieving high-performance phosphorescent organic light-emitting diodes using thermally activated delayed fluorescence with low concentration
摘要： We fabricated phosphorescent organic light-emitting diodes (PhOLEDs) using thermally activated delayed fluorescence (TADF) material 10,10'-(4,4'-sulfonylbis(4,1-phenylene)) bis(9,9-dimethyl-9,10-dihydroacridine) (DMAC-DPS) with low concentration, which showed better performance compared with 1,3-bis(carbazole-9-yl) benzene (mCP) based devices. When the concentration of DMAC-DPS was 1wt%, the driving voltage of the device was only 3.3 V at 1 000 cd/m2, and the efficiency and lifetime of the device were effectively improved compared with those of mCP based devices. The result indicated that DMAC-DPS could effectively improve the performance of phosphorescent devices. We believe that the better device performance can be attributed to the optimization of the energy transfer process in the emitter layer and lifetime of triplet excitons by DMAC-DPS. The study may provide a simple and effective strategy to achieve high-performance OLEDs.
关键词： DMAC-DPS,thermally activated delayed fluorescence,triplet excitons,energy transfer,phosphorescent organic light-emitting diodes
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Zhenjiang, China (2019.8.4-2019.8.8)] 2019 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - The Enhanced Light Extraction Top-emitting Organic Light-emitting Diode Based on Metallic Grating Anode
摘要： The performance of optical light out-coupling of Top-emitting organic light-emitting diode (OLED) is mainly suppressed by surface plasmon polaritons (SPP) on the interface between metal and organic layer, and micro-cavity effect between two metal electrodes. To reduce their influence and enhance the light extraction efficiency, an electromagnetic model of top-emitting organic light-emitting diode (TEOLED) with metallic grating anode is proposed in this report. The numerical simulation performance of metallic grating anode that can enhances the light extraction efficiency of OLED by recovering the energy of surface plasmon polariton mode between organic-metal interface. The simulation based on the Finite Element method (FEM) and Finite difference time domain (FDTD) shows the field distribution and transmission spectrum of proposed TEOLED model, and then indicates the ability of metallic grating anode to improve the light extraction efficiency significantly, which provides a new approach to enhance the efficiency of top-emitting OLED.
关键词： metallic grating anode,surface plasmon polariton,organic light-emitting diodes
更新于2025-09-16 10:30:52
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Poly(1,4-phenylene vinylene) Derivatives with Ether Substituents to Improve Polymer Solubility for Use in Organic Light-Emitting Diode Devices
摘要： New ether-substituted poly(1,4-phenylene vinylene) (PPV) derivatives were synthesized via Horner?Emmons coupling. The structures of the monomers and the resultant oligomers were con?rmed by 1H and 13C NMR spectroscopies. The molecular weights of the oligomers were characterized by gel permeation chromatography, giving the number-average and weight-average molecular weights and the corresponding polydispersity indices. Measurements of UV?vis absorption and ?uorescence were used to characterize the optical properties of the oligomers. Estimation of the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels and other electrochemical characteristics of the oligomers were investigated by cyclic voltammetry. Dialkyl and dialkoxy PPV oligomers were also prepared and characterized following the same instrumental methods used for the ether-substituted oligomers, providing a known reference system to judge the performance of the new conjugated oligomers. Devices were fabricated to analyze the electroluminescent characteristics of the oligomers in organic light-emitting diodes.
关键词： PPV derivatives,poly(1,4-phenylene vinylene),OLED,organic light-emitting diodes,Horner?Emmons coupling
更新于2025-09-16 10:30:52
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Highly efficient flexible organic light-emitting diodes based on a high-temperature durable mica substrate
摘要： Muscovite mica is expected to show great potential in flexible optoelectronics due to its superb temperature tolerance, high transmittance, chemical stability, and mechanical durability. This flexible substrate produces sputtered transparent conducting electrodes (TCEs) with excellent film quality with high transmittance and conductivity. In this study, a designed composite TCE consisting of aluminum-doped zinc oxide (AZO) and indium tin oxide (ITO) is proposed to simultaneously maximize flexibility and conductivity. Blue-, green-, and red-emitting flexible organic light-emitting diodes (FOLEDs) using composite TCEs on mica exhibited satisfactory performance with maximum respective electroluminescence efficiencies of 18.1% (38.7 cd/A), 18.7% (66.2 cd/A), and 13.3% (22.2 cd/A). Furthermore, the green-emitting FOLEDs were modified to construct tandem FOLEDs, giving a higher peak efficiency of 27.9% (93.3 cd/A) and saturated green emission. These results can serve as a useful reference for future work on composite TCEs on mica for FOLEDs in display and lighting applications.
关键词： Organic light-emitting diodes (OLEDs),Flexible,Tandem,Indium tin oxide (ITO),Muscovite mica,Aluminum-doped zinc oxide (AZO)
更新于2025-09-16 10:30:52
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Bipolar fluorophores based on intramolecular charge-transfer moieties of sulfone for nondoped deep blue solution-processed organic light-emitting diodes
摘要： Dipolar emitters exhibited excellent performance in organic light-emitting diode (OLED). However, these molecules had intramolecular charge-transfer (ICT) properties, which posed challenge to obtain deep blue emission. In this study, three fluorophores were designed by introducing carbazole and diphenylamine as electron donors and sulfone as electron acceptor due to their mild charge-accepting properties and twisted angles. These materials appeared almost in vertical angles of the dihedral configuration, and exhibited high thermal and electrochemical stability, suitable for solution-processed OLED. The solution-processed non-doped devices based on these three emitters were realized, where two emissions within the standard deep blue emission range were achieved with the Commission International e de l’Eclairage (CIE) coordinates of (0.16, 0.12) and (0.16, 0.15).
关键词： bipolar fluorophores,intramolecular charge-transfer,deep blue,single layer,organic light-emitting diodes
更新于2025-09-16 10:30:52
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High-performance hybrid white organic light-emitting diodes with bipolar host material and thermally activated delayed fluorescent emitter
摘要： Bipolar host material and thermally activated delayed fluorescent (TADF) emitter were used in hybrid white organic light-emitting diodes (OLEDs) with the aim to achieve high performance. First of all, the single color OLEDs was optimized by changing the thickness of hole transporting layer, electron transporting layer and the doping concentration of emission material. Then, white organic light-emitting diodes (WOLEDs) were fabricated on the basis of the former single color OLEDs by modifying the doping concentration of TADF emitter. Finally, an optimized white device shows the best results of 43.67 cd/A, 45.73 lm/W and 18.52% for current efficiency, power efficiency and external quantum efficiency, respectively. This research may supply a theoretical basis for the development of WOLEDs.
关键词： Thermally activated delayed fluorescent (TADF),Energy transfer,Hybrid white organic light-emitting diodes (WOLEDs),Bipolar host material,High performance
更新于2025-09-16 10:30:52