- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Multiscale Simulation of Photoluminescence Quenching in Phosphorescent OLED Materials
摘要： A multiscale simulation protocol to treat triplet–triplet annihilation (TTA) in phosphorescent organic light-emitting diodes (PhOLEDs), in which microscopic parameters are computed with ab initio electronic structure methods, is presented. Virtual photoluminescence experiments are performed on a prototypical PhOLED emission material consisting of 4,4?,4?-tris(N-carbazolyl)triphenylamine and fac-tris(2-phenylpyridine)iridium. The obtained TTA quenching rate is comparable to experimental results in the low-intensity limit.
关键词： multiscale modeling,organic light-emitting diodes,exciton quenching,triplet–triplet annihilation
更新于2025-09-23 15:19:57
-
Converting an organic light-emitting diode from blue to white with Bragg modes
摘要： Organic light-emitting diodes (OLEDs) have been established as versatile light sources that allow for easy integration in large area surfaces and flexible substrates. In addition, the low fabrication cost of OLEDs renders them particularly attractive as general lighting sources. Current methods for the fabrication of white-light OLEDs rely on the combination of multiple organic emitters and/or the incorporation of multiple cavity modes in a thick active medium. These architectures introduce formidable challenges in both device design and performance improvements, namely the decrease of efficiency with increasing brightness (efficiency roll-off) and short operational lifetime. Here we demonstrate, for the first time, white light generation in an OLED consisting of a sub-100 nm-thick blue single emissive layer coupled to the photonic Bragg modes of a dielectric distributed Bragg reflector (DBR). We show that the Bragg modes, although primarily located inside the DBR stack, can significantly overlap with the emissive layer, thus efficiently enhancing emission and outcoupling of photons at selected wavelengths across the entire visible light spectrum. Moreover, we show that color temperature can be tuned by the DBR parameters, offering great versatility in the optimization of white-light emission spectra.
关键词： distributed Bragg reflector,white organic light-emitting diodes (WOLEDs),Fabry-Pérot modes,electroluminescence color conversion,organic semiconductors
更新于2025-09-19 17:13:59
-
Theoretical Studies of Photophysical Properties of Da????a??Aa????a??D-Type Diketopyrrolopyrrole-Based Molecules for Organic Light-Emitting Diodes and Organic Solar Cells
摘要： A series of D–π–A diketopyrrolopyrrole(DPP)-based small molecules were designed for organic light-emitting diode(OLEDs) and organic solar cell(OSCs) applications. Applying the PBE0/6-31G(d,p) method, the ground state geometry and relevant electronic properties were investigated. The first excited singlet state geometry and the absorption and fluorescent spectra were simulated at the TD-PBE0/6-31G(d,p) level. The calculated results revealed that the photophysical properties were affected through the introduction of different end groups. Furthermore, the electronic transitions corresponding to absorption and emission exhibited an intramolecular charge transfer feature. Our results suggest that the designed molecules acted not only as luminescent for OLEDs, but also as donor materials in OSCs. Moreover, they can also be used as potential electron transfer materials for OLEDs and OSCs.
关键词： photophysical properties,organic solar cells(OSCs),organic light-emitting diodes(OLEDs),diketopyrrolopyrrole(DPP)-based molecules,Charge transporting property
更新于2025-09-19 17:13:59
-
Effect of anode surface treatment by oblique ion bombardment method on Organic light-emitting diodes performance
摘要： In this work, The influence of oblique ion bombardment treatment of the surface of indium tin oxide (ITO) thin films, on the surface parameters of the film and then the performance of organic light-emitting diodes (OLEDs) has been investigated. Both commercially available and uniquely fabricated ITO substrates which were deposited by electron beam evaporation method have been employed. The ITO surface characteristics have been investigated by atomic force microscopy (AFM), X ray diffraction (XRD) and UV-Vis-NIR spectrophotometer. Then a typical OLED device was fabricated on different ITO surfaces and characterized by Keitley 2450 and JAZ spectrometer. The results show that after anode surface treatment by means of oblique Argon ion bombardment method, surface roughness is extremely decreased, which resulted in increasing current and power efficiencies and also there was no evidence of ohmic junctions before driving voltage. The maximum ohmic resistance, current and power efficiencies were 371 MΩ, 6.4 cd/A and 0.91 cd/w, respectively. Also it is found that local non-emissive area or dark spots creation reduced for treated surface device. These findings provide a simple way to effectively reduce the roughness of the ITO films as anode to be applied in optoelectronic devices such as OLEDs.
关键词： Surface roughness,Organic light emitting diodes,Oblique ion bombardment,ITO,Surface treatment,Dark spot
更新于2025-09-19 17:13:59
-
Achievement of Higha??Performance Nondoped Blue OLEDs Based on AIEgens via Construction of Effective Higha??Lying Chargea??Transfer State
摘要： There remains an urgent demand for high-quality blue luminogens that can simultaneously achieve high photoluminescence quantum yield (PLQY) in film and high exciton utilization efficiency (EUE) in the electroluminescence (EL) process. In this study, a referable molecular design strategy is developed for blue luminogens via constructing low-lying locally excited (LE) state with an aggregation-induced emission (AIE) characteristic and high-lying charge-transfer (CT) state for the effective triplet-to-singlet conversion channel. 2TriPE-BPI-MCN with the insertion of p-cyano and o-methyl groups is designed to compare with its matrix framework (2TriPE-BPI). They have analogous properties of the lowest singlet (S1) states with blue emission and free of concentration quenching in film; however, 2TriPE-BPI-MCN exhibits unusual response for hydrostatic pressure owing to its S2 state CT characteristics. Therefore, 2TriPE-BPI-MCN can harness more electrogenerated excitons than 2TriPE-BPI, resulting in a better EL performance in nondoped blue organic light-emitting diodes (OLEDs) (CIEx,y = 0.153, 0.147) with high external quantum efficiency of 4.6% and negligible efficiency roll-off. These findings could open a feasible avenue to develop high-quality blue luminogens for high-performance nondoped blue OLEDs.
关键词： organic light-emitting diodes,blue emission,hydrostatic pressure,aggregation-induced emission,charge-transfer state
更新于2025-09-19 17:13:59
-
Thermally Activated Delayed Fluorescence Benzyl Cellulose Derivatives for Nondoped Organic Light-Emitting Diodes
摘要： Thermally activated delayed ?uorescence (TADF) benzyl cellulose derivatives (TBC-X), which contained both carbazole (host) and phthalimide-based TADF dye (guest) moieties, were prepared from 2,3-di-O-benzyl cellulose in high yields. The TBC-X samples were soluble in common organic solvents such as CH2Cl2, CHCl3, THF, and toluene. The photoluminescence spectra of TBC-X spin-coated ?lms had a single emission peak derived only from guest moieties, which indicated e?cient energy transfer from the host to guest moieties. The TBC-10 (with a content of host and guest moieties of 93 and 7, respectively) in a spin-coated ?lm had the highest photoluminescence quantum yield of 55.3% and TADF characteristics. A nondoped organic light-emitting diode with TBC-10 as the emitting layer showed green emission (λ EL = 517 nm) and achieved a maximum external quantum e?ciency of 5.9%.
关键词： Thermally activated delayed ?uorescence,TADF,organic light-emitting diodes,benzyl cellulose derivatives,OLEDs
更新于2025-09-19 17:13:59
-
Organic Electropolymerized Multilayers for Light-Emitting Diodes and Displays
摘要： In electrochemistry, the carbazole generally coupled to dimer but not polymer. This work has reported that organic electropolymerzation (OEP) of 4,4',4"-Tri(N-carbazolyl)triphenylamine (TCTA) would form high crosslinked carbazole polymer by its high activity/reversibility and a synchronous viscosity control. It has significantly improved the OEP film quality of both holes transporting and electroluminescent layers in organic light emitting diodes. As a result, the conductivity and power efficiency of the organic light emitting diodes with TCTA are eight and four times of that without TCTA. A prototype display device with 1.7 inch monochrome passive matrix of 58 ppi under driving chip is successfully fabricated with accurate pixel size and uniform electroluminescence, which makes the big potential of organic electropolymerzation in the electroluminescent application.
关键词： TCTA,Polymerization,Electrochemistry,Carbazole,Organic Light emitting diodes
更新于2025-09-19 17:13:59
-
Impact of pixel surface topography onto thin-film encapsulated top-emitting organic light-emitting diodes performances
摘要： Two di?erent designs of top-emitting green OLEDs (Organic Light-Emitting Diodes) have been studied. The ?rst one presents a planar OLED architecture. The second one presents an OLED having a topographic surface, so as to simulate a pixel partitioning of a display using an electrically insulating, 200 nm-thick, resist. It has been observed that the topography has a large impact on OLED performances. Studying devices using an ALD (Atomic Layer Deposition)-deposited Al2O3 barrier ?lm shows that topographic OLEDs have a lower stability under storage in 65 °C/85% RH conditions compared to planar ones, with a di?erence in ageing models between the two devices. As the ALD deposition technology has a high conformity, which implies that ALD-deposited Al2O3 barrier ?lms should be as good on topographic devices as on planar ones, we inferred that the topographic OLED Achilles’ heel lies rather in the OLED structure rather than in the Al2O3 encapsulation itself. Thus, topographic and planar unencapsulated OLEDs (without Al2O3) were studied: interestingly, it has been observed that planar OLEDs can live several weeks, while topographic OLEDs show a very short shelf lifetime (in laboratory atmosphere, at 21 °C/50% RH), of only a couple of hours. It will be shown that the topographic OLED surface tends to reduce the thickness of the PVD (Physical vapour Deposition)-deposited layers in the OLED, as this is expected for a non-conformal deposition PVD technique, on tapered angle regions of the resist (pixel edges). While this thickness variation would not be critical for thick electrodes, as for instance for bottom-emitting devices made on glass substrates, this thickness reduction turns out to be a critical point for the ultrathin, 15 nm, silver cathode, used as semi-transparent electrode in this top-emitting architecture and will therefore be discussed in the framework of using OLED top-emitting architectures in (micro)display technology.
关键词： Dark spots,Physical vapour deposition,Atomic layer deposition,Organic light-emitting diodes,Topography,Degradation
更新于2025-09-19 17:13:59
-
Highly efficient blue organic light-emitting diodes based on carbene-metal-amides
摘要： Carbene-metal-amides are soluble and thermally stable materials which have recently emerged as emitters in high-performance organic light-emitting diodes. Here we synthesise carbene-metal-amide photoemitters with CF3-substituted ligands to show sky-blue to deep-blue photoluminescence from charge-transfer excited states. We demonstrate that the emission colour can be adjusted from blue to yellow and observe that the relative energies of charge transfer and locally excited triplet states influence the performance of the deep-blue emission. High thermal stability and insensitivity to aggregation-induced luminescence quenching allow us to fabricate organic light-emitting diodes in both host-free and host-guest architectures. We report blue devices with a peak external quantum efficiency of 17.3% in a host-free emitting layer and 20.9% in a polar host. Our findings inform the molecular design of the next generation of stable blue carbene-metal-amide emitters.
关键词： charge-transfer excited states,photoluminescence,carbene-metal-amides,organic light-emitting diodes,external quantum efficiency
更新于2025-09-19 17:13:59
-
Inkjet printing multilayer OLEDs with high efficiency based on the blurred interface
摘要： Inkjet printing technology is considered to be the next generation manufacturing method for organic light-emitting diodes (OLEDs) production because of its simplicity and low cost. However, the dissolution at interfaces in printing process is still one of the great challenges that limits its progress. The present work utilized the dissolution phenomenon innovatively to generate blurred interface during inkjet printing of multi-layer OLEDs, where TAPC and TAPC:TPBi:Ir-complexes were employed as hole transport layer (HTL) and emitting layer (EML) and both of them were dissolvable in butyl benzoate to form the HTL and EML inks. When they were printed sequentially, a blurred interface between HTL and EML was formed because the dissolution phenomenon, which facilitated the exciton formation and charge balance in EML and improved the device performance. With this blurred interface, the maximum current efficiency of 9.8 cd A-1, the maximum power efficiency of 5.0 lm W-1, and the maximum external quantum efficiency of 3.0% were achieved in (fpbt)2Ir(acac) based OLEDs. In contrast, they were only 7.4 cd A-1, 3.9 lm W-1 and 2.2% in devices having a clear interface between HTL and EML.
关键词： organic light emitting diodes (OLEDs),blurred interface,inkjet printing
更新于2025-09-19 17:13:59