Indolo[3,2,1-jk]carbazole-Derived Narrowband Violet-Blue Fluorophores: Tuning the Optical and Electroluminescence Properties by Chromophore Juggling.

The development of rigid polyaromatic building blocks for narrowband violet fluorophores has received tremendous attention. Herein, we designed and synthesized two new triangle-shaped rigid building blocks, namely, 2,5-di-tert-butylindolo[3,2,1-jk]carbazole (tBuICz) and 2,11-di-tert-butylindolo[3,2,1-jk]carbazole-4-carbonitrile (tBuICzCN), and tethered them with different chromophores to yield a series of violet-blue fluorophores, viz., ICzTPA-ICzPICN, and studied their structure-function relationship. The appended chromophores and cyano unit played a vital role in controlling the optical and electrical properties of the compounds. Except triphenylamine-substituted derivatives, the compounds showed pure violet emission (λem ≤ 403 nm). Intriguingly, the compounds exhibited narrow-band emission with a full-width at half-maximum ≤ 40 nm, attributed to the rigidity of the ICz core. The emission of the compounds displayed positive solvatochromism, which is ascribed to the photoinduced intramolecular charge transfer in the excited state. The compounds revealed excellent thermal robustness with T5d ≥ 363 °C. The triphenylamine-featuring derivatives displayed a high-lying HOMO compared to their congeners due to their electron-rich nature. When we applied these materials in organic light-emitting diodes, ICzPI outperformed in the series with an EQEmax of 3.07% and a current efficiency of 1.04 cd/A. Notably, its CIEy ∼ 0.046 precisely matched with the Rec.2020 standard of deep-blue color (CIEy ∼ 0.046).

Three-Color White Photoluminescence Emission Using Perovskite Nanoplatelets and Organic Emitter.

Three organic blue-light-emitting tetraphenylethylene (TPE) derivatives that exhibit aggregation-induced emission (AIE) were used as additives in the preparation of inorganic perovskite-structured green-light-emitting materials for three-color white-light emission. For these organic-inorganic light-emitting materials, two-color (blue and green) light-emitting films based on the CsPbBr3 perovskite-structured green-light-emitting inorganic material were prepared. The three TPE derivatives were prepared by varying the number of bromide groups, and a distinct AIE effect was confirmed when the derivatives were dissolved in a water-tetrahydrofuran mixed solvent containing 90 vol% water. When 0.2 molar ratio of the 1,1,2,2-tetrakis(4-bromophenyl)ethylene (TeBrTPE) additive was mixed with nanocrystal-pinning toluene solvent, the green-light-emission photoluminescence quantum efficiency (PLQY) value at 535 nm was 47 times greater than that of the pure bulk CsPbBr3 without additives and a blue emission at 475 nm was observed from the TeBrTPE itself. When a CBP:Ir(piq)3 film was prepared on top of this layer, three PL peaks with maximum wavelength values of 470, 535, and 613 nm were confirmed. The film exhibited white-light emission with CIE color coordinates of (0.25, 0.36).

Novel Yellow Azo Pyridone Derivatives with Different Halide Atoms for Image-Sensor Color Filters.

Novel yellow azo pyridone dye derivatives were synthesized for use in image-sensor color filters. The synthesized compounds have a basic chemical structure composed of azo, hydroxy, amide, and nitrile groups as well as different halide groups. New materials were evaluated on the basis of their optical, thermal, and surface properties under conditions mimicking those of a commercial device fabrication process. A comparison of their related performance revealed that, among the four prepared compounds, 5-((4,6-dichlorocyclohexa-2,4-dien-1-yl)diazenyl)-6-hydroxy-1,4-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (Cl-PAMOPC) exhibited the best performance as an image-sensor color filter material, including a solubility greater than 0.1 wt% in propylene glycol monomethyl ether acetate solvent, a high decomposition temperature of 263 °C, and stable color difference values of 4.93 and 3.88 after a thermal treatment and a solvent-resistance test, respectively. The results suggest that Cl-PAMOPC can be used as a green dye additive in an image-sensor colorant.

Synthesis and Electroluminescence Property of Green Fluorescent Dopant Including Anthracene and Diphenylamine Moiety.

We have synthesized green fluorescent emitters of N9,N9,N10,N10-tetraphenylanthracene-9,10-diamine (TAD) and N9,N9,N10,N10-tetra-o-tolylanthracene-9,10-diamine (oMe-TAD) including anthracene and diphenylamine moiety and evaluated properties of compounds. The methyl groups were introduced to the diphenylamine to prevent molecular aggregation of the dopant and reduce self-quenching through steric hindrance of molecular structure. In solution state, photoluminescence (PL) maximum wavelength is 508 nm for TAD and 519 nm for oMe-TAD. In film state, PL maximum wavelength is 518 nm for TAD and 527 nm for oMe-TAD. In electroluminescence (EL) spectra, EL maximum wavelength of TAD is 508 nm and EL maximum wavelength of oMe-TAD is 522 nm. The doped device using TAD as green fluorescent dopant exhibited CE of 17.7 cd/A, PE of 7.74 lm/W, and EQE of 6.11%. The doped device using oMe-TAD as dopant exhibited CE of 19.8 cd/A, PE of 7.23 lm/W, and EQE of 5.97%.

Hybrid White Organic Light Emitting Diodes Using Dual Core Blue Fluorescent Emitter.

White OLED (WOLED) devices were fabricated using blue emitting materials, TP-AA-TP, TP-AA-TPB, and TPB-AA-TPB, and yellow emitting material polyphenylenevinylene derivative (PDY 132). Three devices were fabricated with the following structure: ITO/PEDOT:PSS (50 nm)/PDY-132 (40 nm)/NPB (10 nm)/Blue EML (30 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). PDY-132 was used by spin coating, and then three blue fluorescent materials were used by vapor deposition to form a white light emitting device. The color coordinates of WOLED using TP-AA-TP, TP-AA-TPB and TPB-AA-TPB were (0.291, 0.317), (0.317, 0.371) and (0.345, 0.457), respectively. Device using TP-AA-TP as blue emitting material showed the highest efficiencies at 10 mA/cm², L.E of 5.58 cd/A, P.E of 2.16 lm/W and E.Q.E of 2.96%.

New Pyrene Derivatives Having Rigid Imidazole Moiety for Blue Emitters.

Pyrene, imidazole and dibenzofuran were used to synthesize new blue emitters of 1-(4-(dibenzo[b,d]furan-4-yl)phenyl)-2-(pyren-1-yl)-1H-phenanthro[9,10-d]imidazole (BFP-PI) and 1-(4-(dibenzo[b,d]furan-4-yl)phenyl)-4,5-diphenyl-2-(pyren-1-yl)-1H-imidazole (BFP-DPI). In the film state, BFP-PI and BFP-DPI show photoluminescence (PL) maximum values of 462 nm and 459 nm. The relative PL quantum efficiency (PLQY) of BFP-PI and BFP-DPI is 89.16% and 79.2% by using reference compound of 9,10-diphenylanthracene. The device using BFP-PI in the non-doped state as emitting material showed current efficiency (C.E.) of 3 cd/A and external quantum efficiency (E.Q.E.) of 2.15%, and the device using BFP-DPI as emitting material exhibited C.E. of 2.64 cd/A and E.Q.E. of 1.6%.

Three-Dimensional Structures Based on the Fusion of Chrysene and Spirobifluorene Chromophores for the Development of Blue OLEDs.

A new deep-blue chromophore containing a three-dimensionally (3D) shaped CS core composed of fused chrysene and spirofluorene units is synthesized. A pair of m-terphenyl (TP) units is also substituted onto the CS core at two different sets of positions to form two additional compounds: CS-TPTP and TP-CS-TP. The TP-CS-TP compound showed the highest efficiency with an external quantum efficiency (EQE) of 3.05% and Commission Internationale de L'Eclairage coordinates (CIE) of (0.148, 0.098) corresponding to the emission of blue light. This approach for forming a new chromophore is expected to lead to the development of functional organic materials with excellent characteristics.

New Yellow Synergist for Stable Pigment Dispersion of Inkjet Ink.

Minimizing ink droplet and self-dispersed pigment mixture are becoming hot issues for high resolution of inkjet printing. New synergist including sulfonic acid group of PY-74 was suggested and synthesized. Pigment itself did not show water solubility but new synergist, SY-11 exhibited good solubility in water and organic solvents such as DMSO and DMF. When aqueous pigment ink was prepared with SY-11, storage stability of the ink has been remained for 7 days under periodically repeated heating and cooling conditions. Particle size of formulated ink was around 150 nm.

Synthesis and Electroluminescence Properties of New Dual-Core Derivatives.

New blue emitting materials based on dual core concept, TP-AF-TP and TP-HAF-TP were synthesized through boronylation and Suzuki coupling reactions. In the thin film state, TP-AF-TP and TP- HAF-TP exhibited maximum PL values at 445 and 440 nm, respectively. A non-doped OLED device based on TP-AF-TP and TP-HAF-TP showed current efficiency of 3.16 and 2.67 cd/A, respectively. TP-AF-TP exhibited a higher EL efficiency than that of TP-HAF-TP.

Synthesis and Electroluminescence Properties of New Type Multi-Chromophore Emitting Materials for Organic Light-Emitting Diodes.

New three emitting compounds, AK-1, AK-2 and AK-3 including diazocine moiety were synthesized through Suzuki-coupling reaction. Physical properties such as optical, electroluminescent properties were investigated. UV-visible spectrum of AK-1, AK-2 and AK-3 in film state showed maximum 392, 393 and 401 nm. PL spectrum of AK-1, AK-2 and AK-3 showed maximum emission wavelength of 472, 473 and 435 nm. Three compounds were used as EML in OLED device: ITO/2-TNATA (60 nm)/NPB (15 nm)/EML (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). AK-3 OLED device showed C.I.E value of (0.18, 0.26) and luminance efficiency of 0.51 cd/A at 10 mA/cm2. New derivatives including diazocine moiety were introduced as OLED emitting material and the EL efficiency was increased by the proper combination of core and side group.

Synthesis and Property of New Propeller Shaped Emitting Materials for Organic Light-Emitting Devices.

New propeller type emitting compound, namely 3,6-di-anthracen-9-yl-9,10-bis-(4-anthracen-9-yi-phenyl)-phenanthrene[TAnDAP] and 3,6-bis-(10-phenyl-anthracen-9-yl)-9,10-bis-[4-(10-phenyl-anthracen-9-yl)-phenyl]-phenanthrene [TAnPDAP] were synthesized through Suzuki and McMurry reactions. We investigated their physical properties such as optical, electrochemical, and electroluminescent properties. The two compounds were used as an emitting layer in OLED devices: ITO/2-TNATA (60 nm)/NPB (15 nm)/non-doped: TAnDAP or TAnPDAP (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). The TAnDAP OLED device showed C.I.E. value of (0.28, 0.41) and luminance efficiency of 3.81 cd/A at 10 mA/cm2. The TAnPDAP device showed C.I.E. value of (0.20, 0.27) and high luminance efficiency of 5.40 cd/A at 10 mA/cm2. TAnPDAP was found to show better luminance efficiency and C.I.E. value than TAnDAP because it has a bulky 9-phenylanthracene.

Silk fibroin and 4-hexylresorcinol incorporation membrane for guided bone regeneration.

The objective of this study was to demonstrate that a silk fibroin (SF) and 4-hexylresorcinol (4-HR) incorporation membrane could be used for a guided bone regeneration technique. Fourier transform infrared measurements were obtained to determine change of physical property of SF membrane by 4-HR incorporation. Two peri-implant defects, 3.0 × 5.0 mm (width × length), were prepared on the lateral side of the implant hole in the tibia of New Zealand white rabbits (n = 8). The peri-implant defect was left unfilled in the control group. Silk fibroin + 4-HR membrane was applied to the peri-implant defect in the experimental group. The 8 animals were killed at 8 weeks after implantation. Subsequently, removal torque test and histomorphometric evaluation were done. Fourier transform infrared spectroscopy showed no specific chemical interaction between 4-HR and SF. In the histomorphometric analysis, the mean bone regeneration was 18.3 ± 1.9 mm(2) in the experimental group and 9.3 ± 0.9 mm(2) in the control group (P = 0.004). In conclusion, the SF and 4-HR incorporation membrane successfully regenerated bone in the rabbit tibia peri-implant bone defect model.

High-performance blue OLED using multiresonance thermally activated delayed fluorescence host materials containing silicon atoms.

We report three highly efficient multiresonance thermally activated delayed fluorescence blue-emitter host materials that include 5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene (DOBNA) and tetraphenylsilyl groups. The host materials doped with the conventional N7,N7,N13,N13,5,9,11,15-octaphenyl-5,9,11,15-tetrahydro-5,9,11,15-tetraaza-19b,20b-diboradinaphtho[3,2,1-de:1',2',3'-jk]pentacene-7,13-diamine (ν-DABNA) blue emitter exhibit a high photoluminescence quantum yield greater than 0.82, a high horizontal orientation greater than 88%, and a short photoluminescence decay time of 0.96-1.93 µs. Among devices fabricated using six synthesized compounds, the device with (4-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)phenyl)triphenylsilane (TDBA-Si) shows high external quantum efficiency values of 36.2/35.0/31.3% at maximum luminance/500 cd m-2/1,000 cd m-2. This high performance is attributed to fast energy transfer from the host to the dopant. Other factors possibly contributing to the high performance are a T1 excited-state contribution, inhibition of aggregation by the bulky tetraphenylsilyl groups, high horizontal orientation, and high thermal stability. We achieve a high efficiency greater than 30% and a small roll-off value of 4.9% at 1,000 cd m-2 using the TDBA-Si host material.

Organic-Inorganic Hybrid Device with a Novel Deep-Blue Emitter of a Donor-Acceptor Type, with ZnO Nanoparticles for Solution-Processed OLEDs.

Two new deep-blue emitters with bipolar properties based on an organoboron acceptor and carbazole donor were newly synthesized: 2-(9H-carbazol-9-yl)-5-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho [3,2,1-de]anthracen-7-yl)-5H-benzo[b]carbazole (TDBA-BCZ) and 5-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho [3,2,1-de]anthracen-7-yl)-8-phenyl-5,8-dihydroindolo[2,3-c]carbazole (TDBA-PCZ). The two emitters showed deep-blue and real-blue photoluminescence emission in their solution and film states, respectively. The doped spin-coated films were prepared using synthesized materials and showed a root-mean-square roughness of less than 0.52 nm, indicating excellent surface morphology. The doped devices, fabricated via a solution process using TDBA-BCZ and TDBA-PCZ as the dopants, showed electroluminescence peaks at 428 and 461 nm, corresponding to the Commission Internationale de L'éclairage (CIE) coordinates of (0.161, 0.046) and (0.151, 0.155), respectively. The external quantum efficiency (EQE)/current efficiency (CE) of the solution-processed forward devices, with TDBA-BCZ and TDBA-PCZ as dopants, were 7.73%/8.67 cd/A and 10.58%/14.24 cd/A, respectively. An inverted OLED device fabricated using rod-shaped ZnO nanoparticles as an electron injection layer showed a CE of 1.09 cd/A and an EQE of 0.30%.

Synthesis and Electro-Optical Property of Green Fluorescent Emitter Based on Anthracene Core and Optimized Side Groups.

New green emitter is designed and synthesized by selecting anthracene having high photoluminescence quantum yield (PLQY) and diphenylamine side group substituted methyl and t-butyl group: N9,N10-bis(5-(tert-butyl)-2-methylphenyl)-N9,N10-bis(2,4-dimethylphenyl)anthracene-9,10-diamine (3Me-1Bu-TPADA). Photophysical, electrochemical, and electroluminescent (EL) properties of 3Me-1Bu-TPADA were investigated. The maximum photoluminescence (PL) emission wavelengths of 3Me-1Bu-TPADA in solution and in a film were 528 nm and 531 nm, respectively. 3Me-1Bu-TPADA has excellent thermal properties with glass transition temperatures (Tg) of 110 °C, melting temperatures (Tm) of 217 °C of, and degradation temperature (Td) of 330 °C. 3Me-1Bu-TPADA was used as an emitting layer in non-doped devices: ITO/2-TNATA (60 nm)/NPB (15 nm)/3Me-1Bu-TPADA (30 nm)/Alq3 (30 nm)/LiF (1 nm)/Al (200 nm). The 3Me-1Bu-TPADA device showed luminance efficiency of 6.05 cd/A, EQE of 2.68% at 10 mA/cm².

Anthracene Green Fluorescent Derivatives Based on Optimized Side Groups for Highly Efficient Organic Light-Emitting Diode Emitters.

Two green fluorescent materials, N,N,N',N'-Tetra-o-tolyl-anthracene-9,10-diamine (o-Me-TAD) and N,N'-bis(2,5-dimethylphenyl)-N,N'-di-o-tolylanthracene-9,10-diamine (DMe-o-Me-TAD) including anthracene and diphenylamine moiety, were synthesized by Buchwald-Hartwig amination. In solution state, PL maximum wavelength of o-Me-TAD and DMe-o-Me-TAD is 518 nm and 520 nm. The doped device using o-Me-TAD as green fluorescent dopant exhibited CE of 19.78 cd/A and EQE of 5.97%. The doped device using DMe-o-Me-TAD as dopant exhibited CE of 22.37 cd/A and EQE of 7.02% without roll-off. Doped devices fabricated using o-Me-TAD and DMe-o-Me-TAD show the EL peaks at 522 and 523 nm corresponding to the Commission Internationale de L'Eclairage (CIE) coordinates of (0.29, 0.63) and (0.27, 0.61).

New Thermal Latent Catalyst Using Titanium and Organic Ligand for Urethane Polymerization.

New thermal-latent metal catalyst such as tetrakis (lauorate) titanium (LPTi) was designed and synthesized based on a lauroyl peroxide and titanium. The synthetic method is simple with one step reaction. LPTi structure was confirmed by FT-IR analysis, also nano-sized structure of LPTi confirmed using SEM-EDX. LPTi is thermal-latent metal catalyst including titanium that not only promotes urethane synthesis reaction but also increases the dissociation rate of blocked isocyanate. As a result of quantitative analysis of NCO (%) through back titration, when LPTi was added, NCO (%) increased from 2.34% to 3.24%. LPTi can be used as an excellent catalyst for urethane reaction by reducing the polymerization time by about 30% compared to no catalyst. LPTi can be applied to the electronic polymer synthesis.

Synthesis and Blue Pixel Property of New Violet Dye for Image Sensors.

In this study, a blue photoresist with the hybrid dye-pigment system was developed by mixing xanthene-based dye (XPDIA) and blue pigment 15:6 (1:1, 5 wt% of total mixture amount) in order to develop high-performance image sensors with high thermal and chemical stability. The colorant used in this study has the nano-sized particle of around 100 nm and the physical property is related with the photonic property in image sensor application such as the cameras of mobile phone, car black box, security, etc. The hybrid dye-pigment system showed a high transmittance of more than 90% at 450 nm, and Δab showed very low color difference of 0.52. In solvent resistance, high transmittance of 90% was perfectly maintained, and Δab showed low color difference of 1.08. Migration test result exhibited no change at all after dipping in PGMEA transmittance spectrum. These results are due to the high absorption optical properties of XPDIA dye in the HDPS and the high thermal and chemical stability properties of the PB15:6 pigment. As a result, it was confirmed that the mixed blue hybrid spin coating film exhibited excellent thermal and chemical stability as well as good optical property.

High Efficiency Green Fluorescent Dopant Through the Optimized Side Group for Organic Light Emitting Diodes.

OLED light emitting materials have a molecular size corresponding to the nano scale and are converted into light energy when given electrical energy. The new green fluorescent dopant material was successfully synthesized by using anthracene as a central core and introducing a methyl group and tert-butyl group at various positions as diphenylamine group. Two compounds are N9,N9,N10,N10-tetraphenylanthracene-9,10-diamine (TAD) and N9,N10-bis(4-(tert-butyl) phenyl)-N9,N10-di-o-tolylanthracene-9,10-diamine (p-Tb-o-Me-TAD). The synthesized material emits green light with the maximum wavelengths of 508 and 523 nm. p-Tb-o-Me-TAD shows excellent PLQY of 86.2% in solution state. When the synthesized material was used as a dopant in a device, TAD showed current efficiency (CE) of 17.71 cd/A and external quantum efficiency (EQE) of 6.11%. The device using p-Tb-o-Me-TAD dopant exhibited current efficiency (CE) of 24.24 cd/A and external quantum efficiency (EQE) of 7.27%.

Synthesis and Electroluminescence Property of Anthracene Green Fluorescent Derivatives Based on Optimized Side Groups.

Molecular size of OLED emitting materials is nano-metric size and when it is applied to the electric field it emits the light based on the energy conversion result. As new green fluorescent emitters, N,N,N',N'-Tetra-m-tolyl-anthracene-9,10-diamine (m-Me-TAD) and N,N,N',N'-Tetra-p-tolyl-anthracene-9,10-diamine (p-Me-TAD) were synthesized and the properties were evaluated. In solution state, photoluminescence (PL) maximum wavelength is 517 nm for m-Me-TAD and 529 nm for p-Me-TAD. In electroluminescence (EL) spectra, EL maximum wavelength of m-Me-TAD is 518 nm and p-Me-TAD is 533 nm. The doped device using m-Me-TAD as green fluorescent dopant exhibited current efficiency (CE) of 17.41 cd/A and external quantum efficiency (EQE) of 7.41%. The doped device with p-Me-TAD was optimized in order to achieve a green OLED with high efficiency.