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Wavelength-Turnable Organic Micro-ring Laser Arrays from Thermally Activated Delayed Fluorescent Emitters
摘要： Organic solid-state lasers (OSSLs) have been paid great attention due to their ease-of-fabrication, low cost and tailor-made molecular tunability. Optical gain materials of OSSLs are currently focused on fluorescent materials, which can bring only 25% exciton utilization for future current-injection OSSLs due to spin statics under electrical excitation. While thermally active delayed fluorescent (TADF) materials can obtain a theoretical 100% internal quantum efficiency by harvesting triplet excitons. However, OSSLs based on TADF materials remain largely unexplored yet. Here, we report the first TADF-based OSSL from whispering-gallery mode micro-ring resonator arrays fabricated by a confined solution-growth method. The newly designed TADF emitter of carbozyl borondifluoride curcuminoid derivative, namely, CAZ-A, when doped into a host matrix of 4,4'-bis(N-carbazolyl)-1,10-biphenyl (CBP), reaches the highest gain-coefficient of 640 cm-1 at 4 wt%. These MRs with well-controlled sizes and uniform geometries constitute a high quality (cavity quality factor Q ~ 1300) built-in WGM resonators and exhibit outstanding multi-mode laser behaviors. By varying TADF molecule doping concentration, the laser wavelength can be continuously tuned in the red spectral range from 650 nm to 725 nm. As CBP is usually used as the host material for active layers in OLEDs, we believe that CAZ-A/CBP doping material is good candidate for future electrically driven OSSLs.
关键词： wavelength tunability,micro-ring laser arrays,whispering-gallery mode,host-guest doping,thermally activated delayed fluorescence (TADF)
更新于2025-09-12 10:27:22
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Elucidating the effects of guest-host energy level alignment on charge transport in phosphorescent OLEDs
摘要： The correct choice of guest and host molecules in the light-emitting layer is essential for developing high performance phosphorescent organic light emitting devices. However, the effects of the energy level alignment between the guest and the host are yet to be fully elucidated. In this Letter, we use kinetic Monte Carlo simulations to investigate guest-host systems in which the energy gap of the guest and host is fixed, and only the relative energies of the ionization potential/electron affinity are changed to elucidate their effect on charge transport. It was determined that the mobility balance in the blend was sensitive to the energy level alignment, allowing balanced active layer mobility to be achieved despite the hole and electron mobilities being different by around one order of magnitude. It was also found that the mobility of the faster carrier was more sensitive to the energy level alignment than that of the slower carrier due to reduced slower carrier thermalization under deep charge trapping on the guest.
关键词： guest-host energy level alignment,phosphorescent OLEDs,kinetic Monte Carlo simulations,charge transport
更新于2025-09-12 10:27:22
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Universal host materials based on carbazole-formate derivatives for blue, green and red phosphorescent organic light-emitting diodes
摘要： The design of universal hosts suitable for different color dopants is still desired for efficient organic light-emitting diodes (OLEDs). In this work, two novel carbazole-formate based isomers (2CzMC and 4CzMC) with planar donor?π?acceptor (D?π?A) structures were designed and synthesized as the hosts for phosphorescent OLEDs (PhOLEDs). Due to the weak intramolecular charge transfer character and limited conjugation extensions, both 2CzMC and 4CzMC showed wide-bandgap emissions around 380 nm and high triplet energy levels (2.83 eV for 2CzMC, and 2.90 eV for 4CzMC). The photoluminescent spectra of 2CzMC and 4CzMC doped films with blue, green and red phosphors exhibited completely energy transfer from the hosts to the dopants. PhOLEDs devices with similar structures employing these doped film as emitter layers achieved excellent performance. Especially for 4CzMC-FIrpic based blue device, the external quantum efficiency (EQE) reached as high as 18.9%. This study showed a molecular design strategy to develop novel carbazole-based hosts for different color PhOLEDs.
关键词： Phosphorescent Organic Light-Emitting Diodes (PhOLEDs),Host,Carbazole,Wide-bandgap,Formate
更新于2025-09-12 10:27:22
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Highly Efficient Solution-Processed TADF Bluish-Green and Hybrid White Organic Light-Emitting Diodes Using Novel Bipolar Host Materials
摘要： Two pyridine containing bipolar host materials with high triplet energy, 9,10-dihydro-9,9-dimethyl-10-(3-(6-(3-(9,9-dimethylacridin-10(9H)-yl)phenyl)pyridin-2-yl)phenyl acridin (DDMACPy) and N-(3-(6-(3-(diphenylamino)phenyl)pyridin-2-yl)phenyl)-N-phenylbenzenamine (DTPAPy), are synthesized from modifying the commonly adapted host material 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine (DCzPPy). The HOMO levels of DDMACPy (5.50 eV) and DTPAPy (5.60 eV) are found to be shallower than that of DCzPPy (5.90 eV) that leads to the improvement in hole injection from the hole transport layer PEDOT:PSS (WF = 5.10 eV). These host materials are used in the emitting layer of bluish-green organic light-emitting diode (OLED) with the TADF emitter, 9,9-dimethyl-9,10-dihydroacridine-2,4,6-triphenyl-1,3,5-triazine (DAMC-TRZ), as the guest. The DDMACPy-based device shows the highest performance among them with the maximum external quantum efficiency (EQEmax), current efficiency (CEmax) and power efficiency (PEmax) of 21.0%, 53.1 cd A-1 and 44.0 lm w-1 at CIE (0.17, 0.42), respectively. By further doping with the red emitting phosphor iridium(III) bis(2-phenylquinoline)(2,2,6,6-tetramethylheptane-3,5-ionate) [Ir(dpm)PQ2] and yellow emitting phosphor iridium(III) bis(4-(4-t-butyphenyl) thieno[3,2-c]pyridinato-N,C20)acetylacetonate (PO-01-TB) emitters into the bluish-green emitting layer, a TADF-phosphor hybrid white OLED (T-P WOLED) is obtained with excellent EQEmax, CEmax and PEmax of 17.4%, 48.7 cd A-1 and 44.5 lm w-1 at CIE (0.35, 0.44), respectively. Moreover, both the bluish-green and white OLED show the low efficiency roll-off with external quantum efficiencies at the brightness of 1000 cd m-2 (EQE1000) 18.7% and 16.2% respectively, and are the highest performance records among the solution-processed TADF bluish-green and T-P WOLEDs.
关键词： low efficiency roll-off,solution process,bipolar host material,TADF bluish-green organic light-emitting diode,hybrid white organic light emitting diode
更新于2025-09-12 10:27:22
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Manipulating charge carrier transporting of disubstituted phenylbenzoimidazole-based host materials for efficient full-color PhOLEDs
摘要： Many efforts have been focused on exploring highly efficient host materials that capable of function in phosphorescent organic light-emitting devices (PhOLEDs). However, superior hosts reported to date that are generally suitable to full-color devices are rare and the resultant device performances are far from satisfactory. A class of host compounds DCzPBI, POCzPBI, and DPOPBI, incorporating carbazole and diphenylphosphoryl oxide moieties as electron-donating and -accepting groups, respectively, are synthesized and successfully applied as universal hosts in the fabrication of full-color PhOLEDs. The effect of substituted groups on the photophysical, theoretical calculations, and electrochemical characters for host materials is systematically investigated. We adopt the same device architecture to fabricate the blue, green, yellow, and red PhOLEDs with the combination of the three hosts. As a result, DPOPBI and POCzPBI with good charge carrier transporting properties supported the devices with the impressive efficiencies. The best current efficiency (CE) are 23.2, 48.4, 45.7, 21.5 cd A?1 for blue, green, yellow, and red devices, respectively. Even at the brightnesses of 1000 cd m?2, the efficiency roll-offs are only 2% for green and 0.2% for yellow devices, indicating the promising applications as universal hosts for highly efficient PhOLEDs.
关键词： impressive efficiency,phosphorescent organic light-emitting device,good charge carrier transporting property,host material
更新于2025-09-11 14:15:04
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Effect of the Host on Deep-Blue Organic Light-Emitting Diodes Based on a TADF Emitter for Roll-Off Suppressing
摘要： To achieve significant efficiency and low roll-off in thermally activated delayed fluorescence (TADF) material organic light-emitting diodes (OLEDs), it is essential to choose a host that has suitable high triplet energy (T1) and bipolar character to boost the TADF characteristics as a dopant and avoid exciton annihilation. Herein, we present the effect of different host materials on the efficiency of organic light-emitting diodes (OLEDs) based on bis[4-(3,6 dimethoxycarbazole)phenyl]sulfone (DMOC-DPS) deep-blue emitter. The devices with 10 wt.% of an emitter in different electron types of host bis[2-(diphenylphosphino) phenyl] ether oxide (DPEPO), and hole types of host 1,3-bis(N-carbazolyl)benzene (mCP), were fabricated to study the effect on device performance. The results show that an external quantum efficiency (EQE) of 4% and maximum current efficiency (ηc) up to 5.77 cd/A with high luminescence (lmax) 8185 cd/m2 in DPEPO was achieved, compared to 2.63% EQE, ηc 4.12 cd/A with lmax 5338 cd/m2 in mCP in a very simple device structure. As a remarkable result, the roll-off is suppressed at 1000 cd/m2, and for maximum brightness, the roll-off is less than 50%. Further general applications are discussed.
关键词： host,roll-off,OLEDs,TADF,DMOC-DPS
更新于2025-09-11 14:15:04
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Fabrication of a Tyrosine Responsive Liquid Quantum dots based Biosensor Through Host-Guest Chemistry
摘要： Design and fabrication of a smart liquid quantum dots (LQDs) with high biomolecules selectivity and specificity remains a challenge. Herein, a multifunctional calix[4]arene derivatives (PCAD) was rationally designed and applied to fabricate a Tyr-responsive CdSe-LQDs system through host-guest chemistry. Such this biosensor displays an outstanding fluorescence/macroscopic response for Tyr and reversible fluidic features due to the hydrogen interaction between the PCAD of CdSe-LQDs and Tyr. These excellent results highlighted CdSe-LQDs as a promising platform for biological molecules recognition and separation in the future.
关键词： Calix[4]arene,Liquid Quantum dots,Biosensor,Host-Guest Chemistry,Tyrosine detection
更新于2025-09-11 14:15:04
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Metallacycle-Cored Supramolecular Polymers: Fluorescence Tuning by Variation of Substituents
摘要： Herein, we present a method for the preparation of supramolecular polymers with tunable fluorescence via the combination of metal-ligand coordination and phenanthrene-21-crown-7(P21C7)-based host-guest interaction. A suite of rhomboidal metallacycles with different substituents were prepared via the coordination-driven self-assembly of a P21C7-based 60° diplatinum (II) acceptor and 120° dipyridyl donors. By the variation of the substituents on the dipyridyl donors, the metallacycles exhibit emission wavelengths spanning the visible region (λmax = 427-593 nm). Metallacycle-cored supramolecular polymers were obtained via host-guest interactions between bis-ammonium salts and P21C7. The supramolecular polymers exhibit similar emission wavelengths of the individual metallacycles and higher fluorescent efficiency in solution and thin films. Utilizing a yellow-emitting supramolecular polymer thin film with high quantum yield (0.22), a white-light-emitting LED was fabricated by painting the thin film onto an ultra violet-LED. This study presents an efficient approach for tuning the properties of fluorescent supramolecular polymers and potential of metallacycle-cored supramolecular polymers as a platform for the fabrication of light-emitting materials with good processability and tunability.
关键词： host-guest interaction,fluorescence tuning,supramolecular polymers,metallacycles,light-emitting materials
更新于2025-09-11 14:15:04
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Molecular recognition and fluorescent sensing of urethane in water
摘要： Molecular recognition and fluorescent sensing of Group 2A carcinogen -- urethane was achieved in aqueous solution. The molecular sensors are the endo-functionalized molecular tubes with amide protons in the hydrophobic cavity. 1H NMR, fluorescence, and ITC titrations and single crystal X-ray crystallography reveal the binding stoichiometry, the binding affinities, and the driving forces. The binding is mainly driven by the hydrophobic effect through releasing the “high-energy” cavity water with minor contribution from hydrogen bonding. In addition, the syn-configured molecular tube was found to be a good fluorescent sensor for urethane in water (concentration range: 6.2 μmol/L - 60 μmol/L) and in beer (concentration range: 22.9 μmol/L – 60 μmol/L).
关键词： Molecular recognition,Urethane,Host-guest Chemistry,Fluorescent sensing
更新于2025-09-10 09:29:36
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Triarylboryl-substituted carbazoles as bipolar host materials for efficient green phosphorescent organic light-emitting devices
摘要： Two novel bipolar host materials based on carbazole and triarylborane moieties, i.e. B-2CZ and m-B-CZ, are synthesized and characterized. The spatially crowded compound B-2CZ exhibits a high thermal stability (Td > 340 °C) compared to the reported triarylboryl carbazoles, presumably due to the highly compact architecture. As a result, phosphorescent Ir(ppy)3 combined with both the borylated compounds is selected to construct a host-guest system. Devices A (B-2CZ) and B (m-B-CZ) achieve peak efficiencies of 19.3% (69.1 cd/A and 88.1 lm/W) and 19.1% (66.1 cd/A and 77.2 lm/W), respectively. The respective turn-on voltages of devices A and B are recorded at 2.4 and 2.6 V, which are much lower than that of device with the benchmark host (mCP, 3.3 V). In addition, at a higher practical luminance of 100 cd/m2 (1000 cd/m2), the external quantum efficiencies of devices A and B are still preserved at 19.1% (17.3%) and 18.2% (13.0%) with the mitigated efficiency drops of 1% (10%) and 5% (32%), suggesting the promising advantage for realizing efficient phosphorescent organic light-emitting devices.
关键词： Carbazole,Triarylborane,Bipolar host,Phosphorescent organic light-emitting devices
更新于2025-09-10 09:29:36