Synthesis and characterization of new blue-light-emitting polymers based on PPP and PPV having fluorene pendant at vinyl bridge

Kim, Yun-Hi,Jung, Sang-Yun,Jung, Sung Ouk,Park, Moon-Hak,Kwon, Soon-Ki Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of polymer science Part A, Polymer chemist Vol.44 No.16

<P>The new poly(arylene vinylene) derivatives, which are composed of biphenylene vinylene phenylene vinylene, biphenylene vinylene m-phenylene vinylene, terphenylene vinylene phenylene vinylene, and terphenylene vinylene m-phenylene vinylene as backbone and bulky fluorene pendants at each vinyl bridge, were designed, synthesized, and characterized. The obtained polymers showed weight-average molecular weights of 11,100–39,800 with polydispersity indexes ranging from 1.5 to 2.1. The resulting polymers were amorphous with high thermal stability and readily soluble in common organic solvents. The obtained polymers showed blue emission (λ<SUB>max</SUB> = 456–475 nm) in PL spectra, and polymer 4 containing terphenylene vinylene m-phenylene vinylene showed the most blue shifted blue emission (λ<SUB>max</SUB> = 456 nm). The double layer light-emitting diode devices fabricated by using obtained polymers as emitter emitted bright blue light. The device showed turn on voltage around 6.5 V and brightness of 70–250 cd/m<SUP>2</SUP>. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4923–4931, 2006</P> <B>Graphic Abstract</B> <P>The new poly(arylene vinylene) derivatives, which are composed of biphenylene vinylene phenylene vinylene, biphenylene vinylene m-phenylene vinylene, terphenylene vinylene phenylene vinylene, and terphenylene vinylene m-phenylene vinylene as backbone and bulky fluorene pendants at each vinyl bridge, were designed and synthesized by the Suzuki coupling and nickel(0)-mediated polycoupling. <img src='wiley_img/0887624X-2006-44-16-POLA21579-gra001.gif' alt='wiley_img/0887624X-2006-44-16-POLA21579-gra001'> </P>

Synthesis and characterization of fluorene-based copolymers containing siloxane or distilbene moieties on their main chain

Cho, Hoon-Je,Park, Moo-Jin,Hwang, Do-Hoon,Ahn, Taek,Hong, Ji-Won,Lee, Jonghee,Cho, Nam Sung,Shim, Hong-Ku Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of polymer science Part A, Polymer chemist Vol.47 No.6

<P>Two novel types of polyfluorene copolymers containing siloxane linkages or distilbene moieties on their main-chains were synthesized by Ni(0)-mediated Yamamoto coupling polymerization. These polymers, designated P2Silo05, P2Silo15, PF-P02, and PF-P05 were prepared by copolymerization between 2,7-dibromo-9,9′-dihexylfluorene and bis(bromobenzene)-terminated disiloxane monomer (for P2Silo05 and P2Silo15) or dibromodistilbene monomer (for PF-P02 and PF-P05). All of the polymers were highly soluble in common organic solvents such as chloroform, toluene, and p-xylene. The glass transition temperatures of the polymers were between 92 and 113 °C, and the decomposition temperatures for a 5% weight loss (T<SUB>d</SUB>) were above 420 °C for all of the polymers, demonstrating high thermal stability. The molecular weight (M<SUB>w</SUB>) of the polymers ranged from 4.2 × 10<SUP>4</SUP> to 8.8 × 10<SUP>4</SUP>. The blue shift of the maximum in the UV-visible absorption was greater in polymers with a higher molar percentage of siloxane linkages or distilbene moieties than in homo poly (dihexylfluorene) (PDHF). However, the photoluminescence spectra of the polymers were similar to those of PDHF in terms of the onsets and patterns. Single-layer light-emitting diodes were fabricated with a configuration of ITO/PEDOT:PSS/polymers/Ca/Al. The maximum electroluminescence emission wavelengths of the polymers were 425–450 nm, corresponding to pure blue light. The CIE co-ordinates of the polyfluorenes containing siloxane linkages or distilbene moieties ranged from (0.21, 0.21) to (0.17, 0.10), indicating deeper blue light than that of PDHF {CIE co-ordinates of (0.25, 0.29)}, with P2Silo15 giving the deepest blue-light {CIE co-ordinates of (0.17, 0.10)}. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1595–1608, 2009</P> <B>Graphic Abstract</B> <P>We have synthesized two types of polyfluorene copolymers containing siloxane linkages or distilbene moieties on their main-chains. To the best of our knowledge, P2Silo05 and P2Silo15 are the first polyfluorene copolymers that contain siloxane linkages on their main-chains. Interestingly, the CIE coordinates of the polyfluorenes containing siloxane linkages or distilbene moieties ranged from (0.21, 0.21) to (0.17, 0.10), indicating a deeper blue light emission than that of PDHF {CIE coordinates of (0.25, 0.29)}. <img src='wiley_img/0887624X-2009-47-6-POLA23259-gra001.gif' alt='wiley_img/0887624X-2009-47-6-POLA23259-gra001'> </P>

Blue-Light-Emitting Photostable Hybrid Films for High-Efficiency Large-Area Light Converter and Photonic Applications

Kang, Jung-Soo,Kang, Jun-Gill,Sohn, Youngku,Leung, Kam Tong American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.51

<P>A blue fluorophore of Schiff base zinc complex is prepared by a hydrolysis-free solution-based synthetic method. Under ultraviolet (UV) excitation, the complex produces blue emission with a quantum yield (<I>Q</I>) of 42.6% in methylene chloride and 24.0% in standalone powder form. Quantum mechanical calculations show that the blue emission is generated by the change in the chemical state of the ligand associated with the complexation with Zn cations. Thin films of Zn complexes incorporated in polymethylmethacrylate (PMMA) and cellulose acetate butyrate (CAB) polymers are also prepared by dispersing the complexes into the polymer matrices. These hybrid polymer films exhibit several notable features, particularly enhanced luminescence efficiency (with maximum <I>Q</I> of 85.8% for PMMA and 30.0% for CAB) and scalability for fabrication over a large area while retaining the original properties of the host polymers. Light-emitting diodes are also fabricated using the CAB hybrid thin films, and they show a Q of 43.2% with excellent photostability. The complex and its hybrid films demonstrate their great potential for such applications as UV-to-blue conversion devices in photoelectronics, solar-cell concentrators, solid-state lighting and display, and greenhouse agriculture.</P> [FIG OMISSION]</BR>

Simple modification of anthracene for the blue emitting materials

Kim, Si Hyun,Lee, Seung Hee The Korean Society of Applied Science and Technolo 2017 한국응용과학기술학회지 Vol.34 No.1

Anthracene has been a motive molecule for the blue-emitting materials in OLED. Since the blue emission needs big band gap between HOMO and LUMO, the blue-emitting materials are rare. In this paper, some anthracene derivatives containing simple aryl groups are synthesized and characterized. Regardless of the substituents the absorption and the emission bands are similar to each other and similar to the derivatives with the bulky silyl groups. The thermal and the CIE tests imply that among the tested 9-(2-naphthyl)-10-phenylanthracene is most promising for the diode. The material for the emission layer has to be investigated, which is simple to be prepared as well as good in the electrical and the thermal properties.

Simple modification of anthracene for the blue emitting materials

김시현,이승희 한국응용과학기술학회 2017 한국응용과학기술학회지 Vol.34 No.1

Anthracene has been a motive molecule for the blue-emitting materials in OLED. Since the blue emission needs big band gap between HOMO and LUMO, the blue-emitting materials are rare. In this paper, some anthracene derivatives containing simple aryl groups are synthesized and characterized. Regardless of the substituents the absorption and the emission bands are similar to each other and similar to the derivatives with the bulky silyl groups. The thermal and the CIE tests imply that among the tested 9-(2-naphthyl)-10-phenylanthracene is most promising for the diode. The material for the emission layer has to be investigated, which is simple to be prepared as well as good in the electrical and the thermal properties.

Simple modification of anthracene for the blue emitting materials

Si Hyun Kim,Seung Hee Lee 한국유화학회 2017 한국응용과학기술학회지 Vol.34 No.1

Anthracene has been a motive molecule for the blue-emitting materials in OLED. Since the blue emission needs big band gap between HOMO and LUMO, the blue-emitting materials are rare. In this paper, some anthracene derivatives containing simple aryl groups are synthesized and characterized. Regardless of the substituents the absorption and the emission bands are similar to each other and similar to the derivatives with the bulky silyl groups. The thermal and the CIE tests imply that among the tested 9-(2-naphthyl)-10-phenylanthracene is most promising for the diode. The material for the emission layer has to be investigated, which is simple to be prepared as well as good in the electrical and the thermal properties.

Tetraphenylimidazole-Based Excited-State Intramolecular Proton-Transfer Molecules for Highly Efficient Blue Electroluminescence

Park, Sanghyuk,Seo, Jangwon,Kim, Se Hun,Park, Soo Young WILEY-VCH Verlag 2008 Advanced Functional Materials Vol.18 No.5

<P>Aiming for highly efficient blue electroluminescence, we have designed and synthesized a novel class of tetraphenylimidazole- based excited-state intramolecular proton-transfer (ESIPT) molecules with covalently linked charge-transporting functional groups (carbazole- and oxadiazole-functionalized hydroxyl-substituted tetraphenylimidazole (HPI), i.e., HPI-Cbz and HPI-Oxd, respectively). High T<SUB>g</SUB> (ca. 130 °C) amorphous films of HPI-Cbz and HPI-Oxd showed intense and ideal blue-light emission (λ<SUB>max</SUB> = 462 and 468 nm, Φ<SUB>PL</SUB> = 0.44 and 0.38) with a large Stokes shift of over 160 nm and a narrow full width at half-maximum of less than 65 nm. Organic light-emitting devices using HPI-Cbz and HPI-Oxd as the emitting layer generated an efficient blue electroluminescence (EL) emission peaking at around 460 nm with excellent CIE coordinates of (x, y) = (0.15, 0.11). A maximum external quantum efficiency of 2.94%, and a maximum brightness of 1 229 cd m<SUP>−2</SUP> at 100 mA cm<SUP>−2</SUP>, as well as a low turn-on voltage of 4.8 V were achieved in this work.</P> <B>Graphic Abstract</B> <P>Novel hydroxyl-substituted tetraphenylimidazole derivatives promise efficient bright-blue electroluminescence as shown in the figure. Devices based on these structures attained current densities of 1.96 cd A<SUP>−1</SUP> and quantum efficiencies of up to 2.94%. The devices also showed much improved morphological and thermal stability. <img src='wiley_img/1616301X-2008-18-5-ADFM200700827-content.gif' alt='wiley_img/1616301X-2008-18-5-ADFM200700827-content'> </P>

Enhanced Native Acceptor-related Blue Emission of ZnO Thin Films Annealed in an Oxygen Ambient

심은희,Choeun Lee,Eiwhan Jung,Jinyong Lee,김두수,이영민,김득영,이세준 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.11

The thermodynamic behaviors of charged point defects in the unintentionally-doped ZnO thin films were investigated. The as-grown sample displayed two different types of blue-emission bands: one is at ~2.95 eV from native-donor zinc-interstitial Zn<SUB>i</SUB> and the other is at ~3.17 eV from native-acceptor zinc-vacancy V<SUB>Zn</SUB>. In the samples annealed at oxygen ambience, V<SUB>Zn</SUB>-related emission was dramatically enhanced and Zn<SUB>i</SUB>-related emission was drastically reduced. The behavior was observed to become more apparent when the annealing temperature was increased. The results can be explained by both the increased generation probability and the lowered formation enthalpy of V<SUB>Zn</SUB> in oxygen-rich environment, particularly at higher temperature.

Ultrahighly-efficient and pure deep-blue thermally activated delayed fluorescence organic light-emitting devices based on dimethylacridine/thioxanthene-S,S-dioxide

Jeon, Young Pyo,Kong, Byung Ki,Lee, Eun Jung,Yoo, Keon-Ho,Kim, Tae Whan Elsevier 2019 Nano energy Vol.59 No.-

<P><B>Abstract</B></P> <P>A novel deep-blue emissive dopant material, 2,7-bis(9,9-dimethylacridine-10(9H)-yl)-9,9-diphenyl-9H-thioxanthene 10-,10-dioxide (DMA-ThX), is synthesized for use in highly-efficient thermally activated delayed fluorescence organic light-emitting devices (TADF OLEDs). The molecular design of DMA-ThX retains the overlap between the lowest singlet excited state (S<SUB>1</SUB>) and the lowest triplet excited state (T<SUB>1</SUB>) because of its twisted molecular structure. From photoluminescence emission measurements at low temperature, the difference between the S<SUB>1</SUB> and the T<SUB>1</SUB> energy levels of DMA-ThX is found to be 0.07 eV. Furthermore, the external quantum efficiency of the deep-blue-emitting TADF OLEDs with DMA-ThX-doped bis[2-(diphenylphosphino)phenyl] ether oxide is 18.4%, which is significant, and the Commission Internationale de l'Eclairage coordinates are (0.14, 0.14), indicative of very pure deep-blue emission.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A deep-blue TADF organic material DMA-ThX is synthesized. </LI> <LI> The bandgap of DMA-ThX is 3.4 eV corresponding to deep-blue emission. </LI> <LI> The gap (ΔEST) between S1 and T1 energy levels is 0.07 eV. </LI> <LI> Tg and Tm of DMA-ThX are above 150 and 300 °C, respectively. </LI> <LI> External quantum efficiency of the device is 18.4% with (0.14, 0.14) in CIE. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Strategies for improving luminescence efficiencies of blue-emitting metal halide perovskites

Grandhi G. Krishnamurthy,김하준,Viswanath N. S. M.,조한빈,한주형,김성민,Im Won Bin 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.1

Lead halide perovskites (LHPs) are suitable as the emissive layers in light-emitting diodes (LEDs). The external quantum effi ciency of green LEDs based on LHPs is now over 20%. Nevertheless, the blue LHP LEDs lag behind the green ones in terms of effi ciency. Photoluminescence (PL) quantum yield (QY) and stability of the NCs under various operating conditions are two major factors that infl uence the LED performance. Therefore, to promote the eff orts towards achieving improved LED effi ciencies, herein, we summarize several synthetic methods that produce blue-emitting LHP NC, followed by several approaches devised to boost their PL QYs up to near unity. Light-induced anion segregation is one of the limitations of using blue-emitting mixed-halide LHPs, which triggers the attention to single halide, quantum-confi ned LHP nanoplatelets (NPLs). Syntheses, structure, and luminescent properties of organic–inorganic and all-inorganic blue-emitting LHP NPLs are discussed elaborately. In the last portion, the luminescent properties of lead-free metal halides, which are of current interest, are discussed, followed by an outlook and future directions. In conclusion, our review discusses various literature attempts to obtain stable blue-emitting LHP NCs, which can be helpful in a better design of the blue-emitting LHP NCs towards various light-emitting applications.