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Inkjet Printing of SiO2 Hollow Spheres/Polyimide Hybrid Films for Foldable Low-k ILD
摘要： We demonstrate inkjet printing as a viable method for flexible interlayer dielectrics (ILDs) films with a low dielectric constant, excellent mechanical characteristics, and thermal properties in foldable organic light emitting diodes (OLEDs). SiO2 hollow spheres (SHSs)/polyimide (PI) hybrid films were printed by SiO2 coated polystyrene (PS) ink and PI ink. The relative permittivity of the hybrid films decreased from 3.45 to 1.87. The thermally stable PI fims maintained their weight below 500 °C from the TGA result. The dielectric constant and current density retained their properties after 50,000 cycles of bending at a 1 mm bend radius. We propose that the inkjet printing of SHSs/PI hybrid films described herein is a promising approach for flexible ILDs in foldable OLEDs.
关键词： SiO2 hollow sphere,polyimide,foldable OLEDs,low-k material,inkjet printing,interlayer dielectric
更新于2025-09-10 09:29:36
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Phenyl and Pyrazolyl Functionalized Pyrimidine: Versatile Chromophore of Bis-Tridentate Ir(III) Phosphors for Organic Light Emitting Diodes
摘要： There is a growing interest in the bis-tridentate Ir(III) emitters as they are expected to display both the improved emission efficiency and photostability. Herein, we turned to the new emitters m2h-1 - 3 and m6h-1 - 3, bearing a pincer carbene ancillary and a chromophoric chelate derived from judiciously selected phenyl-pyrimidine-pyrazole entities (pzm2hF)H2 or (pzm6hF)H2, which differ in terms of the location of phenyl and pyrazole substituents on central pyrimidine. DFT calculations revealed a notable change of spin density distribution from the pyrimidine-pyrazolate entity in m2h to pyrimidine-phenyl fragment in m6h. As a consequence, the m6h emitters exhibited both the shortened emission lifetime and improved stability under extensive photolysis in solution, while corresponding OLEDs doped with green emitting m6h-1 and sky-blue emitting m6h-2 and m6h-3 exhibited external quantum efficiencies of 17.6%, 15.9% and 17.6%, superior to all their m2h counterparts at a practical luminance of 103 cd/m2. This finding suggests a new methodology in fine-tuning the electronic transition that is important to high-performance and durable phosphorescent OLEDs.
关键词： phosphorescent OLEDs,organic light emitting diodes,bis-tridentate Ir(III) emitters,photostability,pyrimidine
更新于2025-09-09 09:28:46
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Exciton-Induced Degradation of Hole Transport Layers and Its Effect on the Efficiency and Stability of Phosphorescent Organic Light-Emitting Devices
摘要： The effect of exciton-induced degradation of hole transport layers (HTLs) and its influence on efficiency and stability of phosphorescent organic light emitting devices (PhOLEDs) are investigated. In order to be able to isolate and study the effect of excitons on HTLs, UV illumination as a means to expose them to exciton stress is used. Results reveal that exciton stress of only the HTLs can lead to a significant deterioration in the electroluminescence external quantum efficiency and stability of PhOLEDs, revealing the detrimental role of exciton-induced degradation of HTLs in limiting the device performance. The creation of quenchers in HTLs and the diffusion of excitons from the HTL to the EML appear to play roles in this degradation mechanism. Observations reveal that exciton-induced degradation of HTLs more strongly impacts PhOLEDs than their fluorescent counterparts, revealing the more critical role that HTLs play in influencing their stability and pointing to the role of triplet excitons in this phenomenon. Observations also suggest that increasing the exciton stability of HTLs or reducing exciton lifetime in them can help increase device stability. The findings uncover a new degradation mode in PhOLEDs and provide key insights for device design for realizing better performance and stability.
关键词： electroluminescence efficiency,device stability,phosphorescent OLEDs,exciton-induced degradation,hole transport layers
更新于2025-09-04 15:30:14
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Fluorescent 1,3-Azaphospholes with Pyrrolo[1,2-a]quinoline Skeletons
摘要： The authors report the synthesis and fluorescent behavior of 1,3-azaphosphole oxides and sulfides having pyrrolo[1,2-a]quinoline skeletons. To demonstrate the potential optical applications of these fluorophores, 2cO was used to fabricate electroluminescent devices and was also utilized for live-cell and in vivo imaging.
关键词： OLEDs,fluorescence,pyrrolo[1,2-a]quinoline,azaphospholes
更新于2025-09-04 15:30:14