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Strategies towards rational design of gold(iii) complexes for high-performance organic light-emitting devices
摘要： Gold(iii) complexes are attractive candidates as phosphorescent dopants in organic light-emitting devices for high-luminance full-colour displays. However, no data on the stability of such devices have been reported to date. Through rational molecular design and synthesis, we have successfully generated a new class of cyclometalated gold(iii) C^C^N complexes with tunable emission colours spanning from sky-blue to red. These complexes exhibit high photoluminescence quantum yields of up to 80% in solid-state thin films, excellent solubility and high thermal stability. Solution-processable and vacuum-deposited organic light-emitting devices based on these complexes operate with external quantum efficiencies of up to 11.9% and 21.6%, respectively, and operational half-lifetimes of up to 83,000 h at 100 cd m?2.
关键词： operational stability,phosphorescent dopants,organic light-emitting devices,cyclometalated,gold(iii) complexes,C^C^N complexes
更新于2025-11-19 16:56:35
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Novel hole blocking materials based on 2,6-disubstituted dibenzo[ <i>b</i> , <i>d</i> ]furan and dibenzo[ <i>b</i> , <i>d</i> ]thiophene segments for high-performance blue phosphorescent organic light-emitting diodes
摘要： Novel hole blocking materials (HBMs) based on 2,6-disubstituted dibenzo[b,d]furan and dibenzo[b,d]thiophene segments, 3,30,300,30 0 0-(dibenzo[b,d]furan-2,6-diylbis(benzene-5,3,1-triyl))tetrapyridine (26DBFPTPy) and 3,30,300,30 0 0-(dibenzo[b,d]thiophene-2,6-diylbis(benzene-5,3,1-triyl))tetrapyridine (26DBTPTPy), are successfully designed and synthesized for high-performance blue phosphorescent organic light-emitting diodes (PhOLEDs) for the first time. Computational simulation is used to investigate the optimal structure, orbital distribution, and physicochemical properties of both molecules. Thermal, optical, and electrochemical analysis shows that 26DBFPTPy and 26DBTPTPy possess high thermal stability, deep HOMO energy levels ((cid:2)7.08 and (cid:2)6.91 eV), and a high triplet energy (ET) (2.75 and 2.70 eV). Blue PhOLEDs with 26DBFPTPy or 26DBTPTPy as a hole blocking layer (HBL) exhibit a low turn-on voltage (3.0 V) and operating voltage (4.5 V) at 1000 cd m(cid:2)2. In addition, the blue PhOLEDs with 26DBFPTPy or 26DBTPTPy show superior external quantum e?ciencies (24.1 and 23.6%) and power e?ciencies (43.9 and 42.7 lm W(cid:2)1). They also show a very small e?ciency roll-o? of about 8.5% from 100 to 1000 cd m(cid:2)2. Furthermore, they exhibit improved lifetimes compared to the similarly designed HBL with a pyridine electron transport unit and a phenyl core structure.
关键词： dibenzo[b,d]furan,hole blocking materials,dibenzo[b,d]thiophene,blue phosphorescent organic light-emitting diodes,high-performance
更新于2025-11-14 15:32:45
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Blue-green-emitting cationic iridium complexes with oxadiazole-type counter-anions and their use for highly efficient solution-processed organic light-emitting diodes
摘要： Cationic iridium complexes are promising phosphorescent dopants for solution-processed organic light-emitting diodes (OLEDs) and counter-anion control has emerged as a facile approach to tailor their properties for high-performance devices. A series of oxadiazole-type anions, 3-(5-phenyl-1,3,4-oxadiazol-2-yl)benzenesulfonate (OXD-SO3?), 3-(5-(4-(tert-butyl)phenyl)-1,3,4-oxadiazol-2-yl)benzenesulfonate (tBuOXD-SO3?) and (3-(5-(4-(tert-butyl)phenyl)-1,3,4-oxadiazol-2-yl)phenyl)trifluoroborate (tBuOXD-BF3?), have been prepared as counter-anions for blue-green-emitting cationic iridium complexes. The photophysical and electrochemical properties of the anions and the complexes have been comprehensively characterized. The anions do not affect the emission properties of the phosphorescent cation and efficiently transfer their energy to the cations in films. Solution-processed, double-layer OLEDs using the complexes as dopants have shown much higher (～1.4) efficiencies than the device using the reference complex with a PF6? counter-anion, owing to the improvement of carrier transport/recombination balance by the electron-trapping effect of oxadiazole-type anions. In particular, the blue-green device using the complex with the OXD-SO3? counter-anion affords a peak current efficiency of 37.6 cd A?1 and a peak external quantum efficiency (EQE) of 15.2%, which is the highest for solution-processed OLEDs based on cationic iridium complexes reported so far.
关键词： solution-processed OLEDs,oxadiazole-type counter-anions,phosphorescent dopants,cationic iridium complexes,high-performance devices
更新于2025-11-14 15:23:50
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Preparation of DNA functional phosphorescent quantum dots and application in melamine detection in milk
摘要： Bio-functionalization of quantum dots (QDs) is of important value in practical applications. With single-stranded DNA (ssDNA) rich in thymine T and thioguanine G taken as the template, a new-type nanocomposite material (ssDNA-PQDs) synthesized from low-toxicity T-ssDNA functionalized Mn–ZnS and room-temperature phosphorescent (RTP) QDs (PQDs) was prepared in this paper by optimizing synthesis conditions, and these ssDNA-PQDs could emit orange RTP signals at 590 nm. As these ssDNA-PQDs are rich in T sequences and T sequences can bond with melamine through the hydrogen-bond interaction, ssDNA-PQDs experience aggregation, thus causing phosphorescent exciton energy transfer (PEET) between ssDNA-PQDs of di?erent particle sizes and their RTP quenching. Based on this principle, an RTP detection method for melamine was established. The linear range and detection limit of the detection method are 0.005–6 mM and 0.0016 mM respectively. As this method is based on the RTP nature of ssDNA-PQDs, it can avoid disturbance from background ?uorescence and scattered light of the biological ?uid, and it is very suitable for melamine detection in the biological ?uid milk.
关键词： DNA functionalized quantum dots,milk safety,melamine detection,room-temperature phosphorescent
更新于2025-11-14 15:23:50
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Non-doped phosphorescent organic light-emitting devices with an exciplex forming planar structure for efficiency enhancement
摘要： Organic light-emitting devices (OLEDs) consisting of a non-doped phosphorescent dye that inserted in an exciplex forming planar structure have been fabricated, and the thickness of ultrathin phosphor layer is optimized to achieve high efficiency. The results showed that OLEDs based on the exciplex interface and a 0.5 nm thick phosphorescent dye have a power efficiency, a current efficiency, and an external quantum efficiency of 37.4 lm/W, 40.5 cd/A, and 14.3%, respectively, which are almost two-folds higher than those with non-exciplex interface devices. Meanwhile, the efficiency roll-off is significantly suppressed. These improved device performances are attributed to the elimination of triplet energy leakage from exciplexes to constituting molecules, efficient energy up conversion of triplet exciplexes and complete host-guest F?rster energy transfer. These results will provide an easily-fabricated and time-saving approach for high-performance OLEDs.
关键词： non-doped,planar structure,Organic light-emitting device (OLED),exciplex,phosphorescent dye
更新于2025-09-23 15:22:29
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Inkjet-printed phosphorescent Iridium(III) complex based paper sensor for highly selective detection of Hg2+
摘要： First of its kind inkjet-printed phosphorescent Iridium(III) complex [Ir(TPQ)2(4-EO2-pic)] paper based chemosensor has been developed for Hg2+ ions. The probe is highly selective towards mercury analyte over other metal ions (Cu2+, Ca2+, Co2+, Cd2+, Pb2+, Zn2+, Ni2+, Mg2+, Mn2+, Al3+, Fe3+, La3+, Ag+, K+, Na+ and Li+). [Ir(TPQ)2(4-EO2-pic)] complex solution gave a visible color change from orange to yellow and significant phosphorescence quenching. Upon addition of aqueous Hg2+, the [Ir(TPQ)2(4-EO2-pic)] inkjet-printed paper gave a significant color change in both normal and UV light. The detection limit was found out as 1.78 × 10-8 M. Cyclic voltammetry (CV) studies were conducted to explore the further utility of [Ir(TPQ)2(4-EO2-pic)] as electrochemical sensor for Hg2+ ions in CH3CN / H2O (v/v = 1/1). The oxidation wave intensity of [Ir(TPQ)2(4-EO2-pic)] at 0.98 V decreased and new reversible oxidation wave was appeared at 0.91 V The binding ratio of the [Ir(TPQ)2(4-EO2-pic)]-Hg2+ complex was determined to be 1:1 according to the Job’s Plot. The probable binding modes of these [Ir(TPQ)2(4-EO2-pic)] with Hg2+ have also been suggested on the basis of the 1H-NMR titration, absorption and luminescence studies.
关键词： Phosphorescent,Iridium(III) complex,Inkjet-printed,Paper sensor,Hg2+ detection
更新于2025-09-23 15:21:21
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Evolution of pure hydrocarbon hosts: simpler structure, higher performance and universal application in RGB phosphorescent organic light-emitting diodes
摘要： In the field of phosphorescent organic light-emitting diodes (PhOLEDs), designing high-efficiency universal host materials for red, green and blue (RGB) phosphors has been quite a challenge. To date, most of the high-efficiency universal hosts reported incorporate heteroatoms, which have a crucial role in the device performance. However, the introduction of different kinds of heterocycles increases the design complexity and cost of the target material and also creates potential instability in the device performance. In this work, we show that pure aromatic hydrocarbon hosts designed with the 9,90-spirobifluorene scaffold are high-efficiency and versatile hosts for PhOLEDs. With external quantum efficiencies of 27.3%, 26.0% and 27.1% for RGB PhOLEDs respectively, this work not only reports the first examples of high-efficiency pure hydrocarbon materials used as hosts in RGB PhOLEDs but also the highest performance reported to date for a universal host (including heteroatom-based hosts). This work shows that the PHC design strategy is promising for the future development of the OLED industry as a high-performance and low-cost option.
关键词： RGB phosphors,PhOLEDs,external quantum efficiencies,phosphorescent organic light-emitting diodes,universal host materials,pure aromatic hydrocarbon hosts,9,90-spirobifluorene scaffold
更新于2025-09-23 15:21:01
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High Performances Thermally Activated Delayed Fluorescence Organic Light-emitting Diodes with Wide Gap Phosphorescent Complex as Sensitizer
摘要： In this work, we demonstrated the high performances electroluminescent (EL) devices based on orange-yellow thermally activated delayed fluorescence emitter (TXO-TPA) by utilizing an iridium complex (FK306) as sensitizer. Compared with reference devices without FK306, these co-doped devices displayed significant enhancement of EL performances, which could be attributed to optimized carriers' distribution and efficient energy transfer. In addition, the presence of FK306 molecules helps to broaden the exciton formation zone in EML2, thus suppressing the quenching of triplet excitons. Finally, the optimized co-doped double-EMLs device obtained superior EL performances with maximum current efficiency, power efficiency and external quantum efficiency up to 58.94 cd/A, 61.69 lm/W and 16.5%, respectively. Even at the high brightness of 1000 cd/m2, EL efficiency as high as 12.67 cd/A can still be retained by the same device.
关键词： Organic Light-emitting Diodes,Sensitizer,Wide Gap Phosphorescent Complex,Thermally Activated Delayed Fluorescence
更新于2025-09-23 15:21:01
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Inkjet printing a small-molecule binary emitting layer for organic light-emitting diodes
摘要： For inkjet-printed organic light-emitting diodes, it is critical to obtain a homogeneous small molecular-based emitting film. In contrast to the conventional strategy of utilizing mixed solvents, we have successfully inkjet printed a binary electrophosphorescent emitter with a single solvent. The binary emitter consists of a new host material of 3-(3,6-di-t-butylcarbazol-9-yl)-3'-(2-(4-t-butylphenyl)benzoimidazol-1-yl)-[1,1'-biphenyl], and an iridium complex dopant of bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)- iridium(III) (Ir(MDQ)2(acac)). Compatible with Ir(MDQ)2(acac), the newly developed host is highly soluble and amorphous with a glass transition temperature of 137 oC upon cooling from the melt. The inkjet printability and film morphology of the emitting layer are strongly dependent both on substrates and the solvents. With the o-dichlorobenzene (o-DCB) as the single solvent, and poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4?-(N-(p-butylphenyl))diphenylamine)] (TFB) as the hole transporting layer, a uniform emitter film morphology without any coffee ring is obtained. The phosphorescent OLEDs with the inkjet-printed emitter yields a maximum current efficiency of 17.89 cd/A, comparable to that of the Ir(MDQ)2(acac)?based OLEDs with spin-cast emitter.
关键词： Dewetting,Coffee ring,Inkjet printing,Phosphorescent OLEDs,Small molecules
更新于2025-09-23 15:21:01
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Carbazole/Benzimidazole-Based Bipolar Molecules as the Hosts for Phosphorescent and Thermally Activated Delayed Fluorescence Emitters for Efficient OLEDs
摘要： A series of carbazole/benzimidazole-based molecules, namely, o-CbzBiz, m-CbzBiz, and p-CbzBiz, were readily synthesized in three steps by integrating carbazole with benzimidazole via the ortho-, meta-, and para-positions of phenyl linked to N-phenyl carbazole. These bipolar molecules exhibited a maximum UV absorption band ranging from 310 to 327 nm and a maximum emission band ranging from 380 to 400 nm. Density functional theory calculations showed that the twist angles between the donor and acceptor moieties of these molecules were from 54.9 to 67.1°. Such a twisted structure hampered the π-electron conjugation within the molecule and resulted in high-lying LUMO levels and triplet energies, which make them suitable to be applied as host materials in OLED devices. Our results showed that a maximum external quantum efficiency (EQE) of OLED reached 21.8% when p-CbzBiz was applied as the host of a green phosphorescent emitter, i.e., Ir(ppy)2(acac). In addition, a maximum EQE of OLED reached 16.7% when o-CbzBiz with the host of a green TADF emitter, i.e., 4CzIPN. Moreover, these devices exhibited lower efficiency roll-off than the CBP-hosted device using the same emitters, which demonstrated the bipolar charge carrier property of carbazole/benzimidazole-based molecules.
关键词： thermally activated delayed fluorescence,bipolar molecules,phosphorescent,carbazole,OLEDs,benzimidazole
更新于2025-09-23 15:21:01