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Regioisomer effects of dibenzofuran-based bipolar host materials on yellow phosphorescent OLED device performance
摘要： Four regioisomers were synthesized for use as bipolar host materials for phosphorescent organic light-emitting diodes (PhOLEDs) by classic cross-coupling reactions using cyanofluorene and fused dibenzofuran and were readily purified. To realize the bipolar host material, a cyano-substituted fluorene was selected as the n-type unit and dibenzofuran as the p-type unit. Yellow PhOLEDs were fabricated with iridium(III) bis(4-phenylthieno[3,2-c]pyridinato-N,C20)acetylacetonate [PO-01] as a phosphorescent emitter. The achieved maximum current efficiency was 77.2 cd A?1 and the external quantum efficiency was 25.3% for the [PO-01]-based PhOLED; the 7-(dibenzo[b,d]furan-2-yl)-9,9-dimethyl-9H-fluorene-2-carbonitrile (CF-2-BzF) host had the best device performance. The color coordinates of yellow PhOLEDs at 1000 cd m?2 were (0.50, 0.50) (CF-1-BzF), (0.50, 0.49) (CF-2-BzF), (0.51, 0.49) (CF-3-BzF), and (0.50, 0.50) (CF-4-BzF).
关键词： regioisomer effects,phosphorescent organic light-emitting diodes,device performance,bipolar host materials,yellow PhOLEDs
更新于2025-09-23 15:19:57
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Theoretical and experimental study on the electronic and optical properties of K <sub/>0.5</sub> Rb <sub/>0.5</sub> Pb <sub/>2</sub> Br <sub/>5</sub> : a promising laser host material
摘要： The data on the electronic structure and optical properties of bromide K0.5Rb0.5Pb2Br5 achieved by first-principle calculations and verified by X-ray spectroscopy measurements are reported. The kinetic energy, the Coulomb potential induced by the exchange hole, spin-orbital effects, and Coulomb repulsion were taken into account by applying the Tran and Blaha modified Becke–Johnson function (TB-mBJ), Hubbard U parameter, and spin-orbital coupling effect (SOC) in the TB-mBJ + U + SOC technique. The band gap was for the first time defined to be 3.23 eV. The partial density of state (PDOS) curves of K0.5Rb0.5Pb2Br5 agree well with XES K Ll and Br Kb2, and XPS spectra. The valence band (VB) is characterized by the Pb-5d3/2 and Pb-5d5/2 sub-states locating in the vicinities of ~20 eV and ~18 eV, respectively. The VB middle part is mainly formed by K-3p, Rb-4p and Br-4s states, in which the separation of Rb-4p3/2 and Rb-4p1/2 was also observed. The strong hybridization of Br-p and Pb-s/p states near ~6.5 eV reveals a major covalent part in the Br–Pb bonding. With a large band gap of 3.23 eV, and the remarkably high possibility of inter-band transition in energy ranges of 4–7 eV, and 10–12 eV, the bromide K0.5Rb0.5Pb2Br5 is expected to be a very promising active host material for core valence luminescence and mid-infrared rare-earth doped laser materials. The anisotropy of optical properties in K0.5Rb0.5Pb2Br5 is not significant, and it occurs at the extrema in the optical spectra. The absorption coefficient a(u) is in the order of magnitude of 106 cm?1 for an energy range of 5–25 eV.
关键词： electronic structure,X-ray spectroscopy,optical properties,laser host material,first-principle calculations,K0.5Rb0.5Pb2Br5
更新于2025-09-23 15:19:57
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Photoresponsive Structured Liquids Enabled by Molecular Recognition at Liquida??Liquid Interfaces
摘要： Using the host-guest molecular recognition at the oil-water interface, a new-type photo-responsive nanoparticle surfactant (NPS), is designed and prepared to structure liquids. With the help of a polymeric surfactant, the interfacial host-guest interactions can be significantly enhanced, leading to a rapid formation and assembly of a NP monolayer, and offering sufficient binding energy to hold the NPs in a jammed state. The assembly of the NPSs can be reversibly manipulated via a photo-switchable jamming to unjamming transition, endowing the interface, as well as the macroscopic assemblies, with responsiveness to the external trigger (photons). This study, for the first time, opens the pathway for the construction of multi-responsive, structured all-liquid systems by introducing host?guest chemistry, showing promising potential applications in encapsulation, delivery systems, and unique microfluidic devices.
关键词： self-assembly,liquid-liquid interfaces,host-guest chemistry,Structured liquid,nanoparticle surfactants
更新于2025-09-23 15:19:57
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Diphenylamine/triazine hybrids as bipolar hosts for phosphorescent organic light-emitting diodes
摘要： The bipolar host materials employing diphenylamine (DPA) as donor unit and triazine (TRZ) as acceptor unit could achieve suitable energy levels and balanced charge transporting properties, which are necessary for high performance of organic light-emitting diodes (OLEDs). In this work, three DPA/TRZ based host materials, named 2-(4-(N,N-diphenylamino)phenyl)-4,6-diphenyl-1,3,5-triazine (DPA-TRZ), 2,4-bis(4-(N,N-diphenylamino)phenyl)-6-phenyl-1,3,5-triazine (DDPA-TRZ), and 2,4,6-tris(4-(N,N-diphenylamino)phenyl)-1,3,5-triazine (TDPA-TRZ) were designed and synthesized. Their thermal, photophysical, electrochemical, and carrier transporting properties were investigated to reveal the relationship between molecular structure and properties. The number of DPA units could regularly tune the optical and electrical properties of the hybrids. The triplet excited state energy (ET) values of DPA-TRZ, DDPA-TRZ, and TDPA-TRZ are 2.38, 2.51, and 2.73 eV, respectively. To evaluate the electroluminescent properties of the three host materials, blue, green, red, and white phosphorescent OLEDs (PhOLEDs) were fabricated and characterized. With the highest ET value, TDPA-TRZ can afford from blue to red phosphorescent emitters. All these devices exhibited EQEs of over 20% with relatively low efficiency roll-offs. The single-host white PhOLEDs based on TDPA-TRZ showed impressive color stability and superior color rendition. These results demonstrate that the combination of DPA and TRZ is an effective way to construct highly efficient bipolar host materials.
关键词： diphenylamine,triazine,phosphorescent organic light-emitting diodes,charge transporting properties,bipolar host materials
更新于2025-09-23 15:19:57
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A negative polaron resistant p-type host for extended lifetime in deep blue phosphorescent organic light-emitting diodes
摘要： A novel mixed host employing a negative polaron stabilizing p-type host was developed to extend the device lifetime of blue phosphorescent organic light-emitting diodes (PhOLEDs). Instead of a conventional p-type host with only a hole transport unit, a p-type host with a negative polaron resistant unit in addition to the hole transport unit was used in the mixed host consisting of a p-type host and an n-type host. The p-type host had benzonitrile as a negative polaron resistant unit which stabilized the molecule under negative polarons. The use of the p-type host with the benzonitrile unit almost doubled the device lifetime of the blue PhOLEDs due to the improved negative polaron stability of the hosts. Therefore, the p-type host with the weak electron accepting benzonitrile unit can play the role of a lifetime extending p-type host to replace a conventional p-type host.
关键词： p-type host,device lifetime,negative polaron,benzonitrile,blue phosphorescent organic light-emitting diodes
更新于2025-09-23 15:19:57
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Dissociative Nature of C(sp2)-N(sp3) bonds of Carbazole Based Materials via Conical Intersection: Simple Method to Predict the Exciton Stability of Host Materials for blue OLEDs: A Computational Study
摘要： In this work, the origin of singlet and triplet exciton-induced degradation of host materials with C(sp2)?N(sp3) bonds around nitrogen (carbazoles, acridines etc), connecting donor and acceptor units, were unravelled using DFT and CASSCF methods. The results reveal that molecules (employed in OLEDs) with basic unit containing C(sp2)?N(sp3) bonds (nitrogen connected to carbon in triangular fashion) have natural tendency to fragment at C-N bond through S1/S0 conical intersection (CI). The calculation of barrier heights, to reach dissociation point, indicates that degradation via triplet states is kinetically less feasible (?G* T1-TS >25 kcal mol-1) compared to first singlet excited state (?G* S1-TS ?7-30 kcal mol-1). However, long lifetime of triplets (as compared to singlets) aids in the reverse intersystem crossing from triplet to singlet state for subsequent degradation. From the results and inference, ?G* S1-TS and ?ES1-T1 are proposed to be the controlling factors for exciton-induced degradation of host materials with C(sp2)?N(sp3) bonds. Further, multiple functionalization of carbazole moieties reveal that polycyclic aromatic systems employed as acceptor unit of host materials are best suited for PhOLEDs as they will increase their lifetime due to larger ?G* S1-TS and ?ES1-T1. For TADF-based devices, materials with fused ring systems (with N(sp3) at the centre) in the donor unit is the most recommended one based on the findings of this work, as it avoids the dissociative channel altogether. Negative linear correlation between ?G* S1-TS and HOMO-LUMO gap is observed, which provides indirect way to predict the kinetic stability of these materials in excitonic states. These initial results are promising for future development of QSAR-type approach for smart designing of host materials for long-life blue OLEDs.
关键词： C(sp2)?N(sp3) bonds,OLED,DFT,degradation,host materials,conical intersection,CASSCF
更新于2025-09-23 15:19:57
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Novel Competitive Fluorescence Sensing Platform for L-carnitine Based on Cationic Pillar[5]Arene Modified Gold Nanoparticles
摘要： Supramolecular host-guest interaction and sensing between cationic pillar[5]arenes (CP5) and L-carnitine were developed by the competitive host-guest recognition for the first time. The fluorescence sensing platform was constructed by CP5 functionalized Au nanoparticles (CP5@Au-NPs) as receptor and probe (rhodamine 123, R123), which shown high sensitivity and selectivity for L-carnitine detection. Due to the negative charge and molecular size properties of L-carnitine, it can be highly captured by the CP5 via electrostatic interactions and hydrophobic interactions. The host-guest mechanism between PP5 and L-carnitine was studied by 1H NMR and molecular docking, indicating that more affinity binding force of CP5 with L-carnitine. Therefore, a selective and sensitive fluorescent method was developed. It has a linear response of 0.1–2.0 and 2.0–25.0 μM and a detection limit of 0.067 μM (S/N = 3). The fluorescent sensing platform was also used to detect L-carnitine in human serum and milk samples, which provided potential applications for the detection of drugs abuse and had path for guarding a serious food safety issues.
关键词： L-carnitine,cationic pillar[5]arenes,host–guest recognition,Au nanoparticles
更新于2025-09-23 15:19:57
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Luminescent Solar Concentrators Based on Renewable Polyester Matrices
摘要： This study reports for the first time the use of bio-based alternatives for PMMA as host matrix for luminescent solar concentrators (LSCs). Notably, two types of renewable polyesters were synthesized in varying molar ratios via a two-step melt-polycondensation reaction with dibutyl tin oxide as catalyst. The first is a homopolymer of diethyl 2,3:4,5-di-O-methylene galactarate (GxMe) and isosorbide (IGPn), and the second is a random copolymer of GxMe with 1,3-propanediol and dimethyl terephthalate (GTPn). The two polyesters were found to be optically transparent, totally amorphous with a Tg higher than 45 8C and temperature resistance comparable to PMMA. Lumogen Red (LR) and an aggregation-induced emission (AIE) fluorophore, TPETPAFN, were utilized as fluorophores and the derived thin polymer films (25 mm) were found highly homogeneous, especially for those prepared from GTPn, possibly due to the presence of compatibilizing terephthalate units in the matrix composition and the higher molecular weight. The spectroscopic characterization and the optical efficiency determination (hopt) evidenced LSCs performances similar or superior to those collected from LR/PMMA thin films. Noteworthy, hopt of 7.7 % and 7.1 % were recorded for the GTPn-based matrix containing LR and TPETPAFN, respectively, thus definitely supporting the bio-based polyesters as renewable and highly high-performance LSCs.
关键词： luminescent solar concentrators,renewable host matrices,aggregation-induced emission,fluorophores,polyesters
更新于2025-09-23 15:19:57
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Mononuclear cell collection for extracorporeal photopheresis by using the <i>“</i> off‐line <i>”</i> system: A comparative study between COBE Spectra and Spectra Optia devices
摘要： Background: Extracorporeal photopheresis (ECP) is an efficient and established therapy to treat acute and chronic graft vs host disease (GVHD). Using an “off-line” method, the first step (mononuclear cell [MNC] collection) is decisive, as long as a high MNC yield and purity in the collected product is desirable. Two “off-line” devices were compared: the COBE Spectra and the Spectra Optia (Terumo BCT), using both continuous and intermittent protocols. Patients and methods: Twelve patients with GvHD (7 acute/5 chronic) were enrolled between June 2014 and May 2015 and were alternatively assigned for each procedure to either the COBE Spectra or the Spectra Optia cell separator. Patients characteristics and procedure/product parameters were analyzed. Results: Two hundred procedures (100 per device) were included. The Spectra Optia system showed higher total nucleated cells and MNC collection efficiencies (18.6(10.2-29.7) vs 7.9(4.1-14.8)% and 43.6(20.3-59.5) vs 23.3(11.4-37.1)%, P < .001) and monocyte and lymphocyte collection efficiencies (55.2(17.7-83.2) vs 22.8(9-38.9)% and 38.3(26.7-53.4) vs 22.2(9-38.9)%, respectively, P < .001). Absolute platelet loss (PL) and PL per liter of blood processed were significantly lower in the Spectra Optia group (22.9(18.3-28.1) vs 33.6(26.5-41.1)%, P < .001 and 3.7(3.1-4.5) vs 4.3(3.5-4.2)%, P = .01, respectively). However, granulocyte contamination was higher (4.5(1.3-36) vs 1.2(0.4-5.7)%, P < .001) and a higher product haematocrit was obtained with the Spectra Optia (1(0.5-1.6) vs 0.3 (0.2-0.5)%, P < .001), without an impact on irradiation time. Conclusions: In our study, Spectra Optia proved to be safe and effective in collecting MNC with high yield and purity for ECP in GvHD.
关键词： mononuclear cell collection,cell separator,graft vs host disease,extracorporeal photopheresis
更新于2025-09-23 15:19:57
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Suppression of device degradation mechanism by triphenylsilyl group substitution of the host for blue phosphorescent organic light-emitting diodes
摘要： The effect of triphenylsilyl group substitution in the host materials for blue phosphorescent organic light-emitting diodes was studied by synthesizing two hole transport type hosts with and without the triphenylsilyl group in the identical backbone structure. The two host materials were applied as the hosts of blue phosphorescent emitter and the comparison of the emission behavior of the two hosts revealed that the triphenylsilyl group suppressed triplet exciton quenching of the blue phosphorescent emitters. As a result, the blue host with the triphenylsilyl group showed improved device efficiency and extended device lifetime in the blue phosphorescent devices. The blue phosphorescent device with the triphenylsilyl group substituted host showed improved external quantum efficiency and elongated device lifetime compared to the triphenylsilyl free host based device. The bulky triphenylsilyl group was effective to extend the device lifetime of the blue phosphorescent device through reduced triplet exciton induced annihilation.
关键词： host,blue device,device lifetime,phosphorescent host
更新于2025-09-19 17:13:59