Spectroelectrochemical Study of the Formation of Radical cations of 4,4’-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl as a Hole Transport Semiconductor Material

2011 ◽  
Vol 1286 ◽  
Author(s):  
Sharavsambuu Baasanjav ◽  
Gendensvren Bolormaa ◽  
Batjargal Naranbileg ◽  
Munkhbat Battulga ◽  
Chimed Ganzorig
Keyword(s):  
Radical Cations ◽  
Band Gap Energy ◽  
Hole Transport ◽  
Emission Region ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Quenching Process ◽  
Hole Transporting ◽  
Uv Visible ◽  
Hole Transporting Material

ABSTRACTSpectroelectrochemical study on a new absorption band of radical cations of 4,4’-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (α-NPD) as an electron-donor hole-transporting material used in organic electronics is reported in this work. UV-visible spectroscopic and cyclic voltammetric properties for α-NPD in solution are also examined. We find that the results are attributed to quenching process for blue fluorescence from α-NPD by excess α-NPD+ radical cations accumulated in the emission region in the organic light-emitting devices related to a relatively large overlap between the fluorescence spectrum of α-NPD and the absorption spectrum of α-NPD+ radical cations. The band gap energy for α-NPD is calculated from the UV-visible spectroscopic data.

A High Tg Carbazole-Based Hole-Transporting Material for Organic Light-Emitting Devices

2005 ◽  
Vol 17 (5) ◽  
pp. 1208-1212 ◽  
Author(s):  
Jiuyan Li ◽  
Di Liu ◽  
Yanqing Li ◽  
Chun-Sing Lee ◽  
Hoi-Lun Kwong ◽  
...  
Keyword(s):  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Hole Transporting ◽  
Organic Light Emitting Devices ◽  
Hole Transporting Material

Organic Light-Emitting Diodes Using Triphenylamine Based Hole Transporting Materials

2000 ◽  
Vol 621 ◽  
Author(s):  
Hisayoshi Fujikawa ◽  
Masahiko Ishii ◽  
Shizuo Tokito ◽  
Yasunori Taga
Keyword(s):  
Thermal Stability ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Hole Transporting ◽  
Hole Transporting Material ◽  
Increasing Temperature

ABSTRACTThe durability of the tris(8-quinolinolato) aluminum based light-emitting diode (LED) is related to the thermal stability of the hole transport layer. Several linear linkage triphenylamine oligomers were used for the hole transport layer. The thermal stability was clearly seen to depend on a glass transition temperature (Tg) of the hole transporting material, and a linear relationship between the Tg and the thermal stability was found. A lowering of “turn-on voltage” for light emission and an increase of luminous efficiency with increasing temperature was also observed. Excellent durability of the organic LED with a tetramer of triphenylamine was achieved at a high temperature of 120°C. Our results indicate that the linear linkage of triphenylamine leads to a high Tg and high device performance at high temperatures.

Both Luminous Efficiency and Lifetime Enhancement in Blue Fluorescence OLEDs by Modifying Molecular Structure of Hole Transporting Material

2011 ◽  
Vol 1286 ◽  
Author(s):  
Yoonhyun Kwak ◽  
Sun-Young Lee ◽  
Hye-In Jeong ◽  
Dae-Yup Shin ◽  
Young-Woo Song ◽  
...  
Keyword(s):  
Energy Levels ◽  
Luminous Efficiency ◽  
Coupling Reactions ◽  
Blue Fluorescence ◽  
Lumo Energy ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Hole Transporting ◽  
Palladium Catalyzed ◽  
Hole Transporting Material

ABSTRACTBoth luminous efficiency and lifetime in blue fluorescence organic light emitting devices (OLEDs) have been improved by modified HTMs with higher LUMO energy levels. The LUMO energy levels of HTM were increased by modifying substituent in HTM molecules. Two HTMs containing ortho and meta biphenyl substituent and one HTM containing thiophene substituent were synthesized via palladium catalyzed amine coupling reactions to compare with a para biphenyl substituent HTM-1 as a standard molecule. According to TDDFT calculations, these three modified HTMs showed 0.05-0.15 eV higher LUMO energy levels compared to the para biphenyl substituent HTM-1. The luminous efficiency and the lifetime (LT90) of OLEDs using HTM-2 at 500 cd/m2 have been enhanced up to 20 % and 52 %, respectively, compared to the standard device using HTM-1.

Synthesis of Carbazole-Based Polymers with 1,3,4-Oxadiazole Pendant Group and Their Application in Organic Light-Emitting Diodes

2008 ◽  
Vol 8 (9) ◽  
pp. 4846-4850
Author(s):  
Hui Wang ◽  
Jeong-Tak Ryu ◽  
Chao Cao ◽  
Younghwan Kwon
Keyword(s):  
Light Emitting Diodes ◽  
Band Gap Energy ◽  
Side Chain ◽  
Visible Absorption ◽  
Homo Energy ◽  
Light Emitting ◽  
Hole Transporting ◽  
Palladium Catalyzed ◽  
Polymer Light Emitting Diodes ◽  
Uv Visible

Structurally well-defined copolymers with high solubility were prepared via palladium-catalyzed polycondensation of N-(2-ethylhexyl)-3,6-dibromocarbazole with 2-aryl-5-(4-aminophenyl)-1,3,4-oxadiazole (aryl = phenyl, p-methylphenyl, p-methoxyphenyl). Copolymers consisted of alkylcarbazole groups in the main chain and 1,3,4-oxadiazole pendants in the side chain. The influence of their aryl substituents on physical, optical, band gaps and electroluminescent characteristics of the copolymers was investigated. Both UV-Visible absorption and photoluminescence emission peaks of the copolymers were similar to each other. The band gap energy of the polymers was measured in the range of 2.84∼2.88 eV, and HOMO energy in the range of −5.13∼−5.18 eV. These copolymers were used as hole-transporting layers (HTL) in the light-emitting diodes with Alq3 as an emitting layer. Compared to devices with P-H and P-OCH3 used as HTL, it should be noted that device with P-CH3 used as HTL showed higher luminescence. Maximum luminescence of devices was measured to be 276cd/m2 at 14 V with P-H, 625 cd/m2 at 15 V with P-CH3, and 471 cd/m2 at 14 V with P-OCH3. This might be due to effect of subtle changes in HOMO energy level of polymers with changing substituent groups. Phosphorescent polymer light emitting diodes were also fabricated with an emitting layer consisting of P-CH3 matrix and a red phosphorescent dopant (Ir-PIQCH).

Light Emitting Devices with Molecularly Doped Polymer Layers. A New Diamine as a Hole Transporting Molecule

1997 ◽  
Vol 488 ◽  
Author(s):  
V. Fattori ◽  
M. Cocchi ◽  
P. Di Marco ◽  
G. Giro ◽  
J. Kalinowski ◽  
...  
Keyword(s):  
Doping Level ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Present Contribution ◽  
Light Emitting ◽  
Polymer Layers ◽  
Light Emitting Devices ◽  
Hole Transporting ◽  
Doped Polymer

AbstractIn the present contribution a new hole transporting molecule belonging to the triphenyldiamine family (N,N'-diphenyl-N,N'-bis(4-metylphenyl)- 1, 1'-biphenyl-4,4'- diamine) in a polycarbonate matrix is studied as the hole transport layer in a two layer device with Alq3 as emitting layer. The dependence of the electrical and emitting behaviour on the doping level is studied and compared with the vacuum deposited diamine layer also interfaced with Alq3

HighTgTriphenylamine-Based Starburst Hole-Transporting Material for Organic Light-Emitting Devices

2007 ◽  
Vol 19 (24) ◽  
pp. 5851-5855 ◽  
Author(s):  
Qing-Xiao Tong ◽  
Shiu-Lun Lai ◽  
Mei-Yee Chan ◽  
Ka-Ho Lai ◽  
Jian-Xin Tang ◽  
...  
Keyword(s):  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Hole Transporting ◽  
Organic Light Emitting Devices ◽  
Hole Transporting Material

Inkjet printing high luminance phosphorescent OLED based on m-MTDATA:TPBi host

2019 ◽  
Vol 33 (12) ◽  
pp. 1950149 ◽  
Author(s):  
Xing Xing ◽  
Tong Lin ◽  
Yong-Xu Hu ◽  
Yu-Ling Sun ◽  
Wan-Ying Mu ◽  
...  
Keyword(s):  
Charge Transfer ◽  
High Performance ◽  
High Luminance ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Single Host ◽  
Hole Transporting ◽  
Phosphorescent Material ◽  
Hole Transporting Material ◽  
Balance Charge

In organic light-emitting devices (OLEDs), the high performance of devices depends on balanced charge transfer in emitting layer (EML). However, the balance charge transfer is hard to achieve in the single host material-based EML. In this work, a high luminance co-host based OLEDs is printed. In detail, green phosphorescent material tris[2-(p-tolyl)pyridine]iridium(III) [Formula: see text] is used as dopant, and a hole-transporting material [Formula: see text]-tris[3-methy-lphenyl(phenyl)amino]-triphenylamine (m-MTDATA) blended with an electron-transporting material 1,3,5-tris(phenyl-2-benzimidazolyl)-benzene (TPBi) as co-host. As a result, the optimized printing co-host OLEDs with 10 wt.% [Formula: see text] shows a maximum luminance of [Formula: see text], which is much higher than the CDBP counterpart.

scholarly journals New materials for Organic Light-Emitting Diodes

1995 ◽  
Vol 413 ◽  
Author(s):  
S. Joshua Jacobs ◽  
Timothy P. Pollagi ◽  
Michael B. Sinclair ◽  
Rodger D. Scurlock ◽  
Peter R. Ogilby
Keyword(s):  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
New Materials ◽  
Light Emitting ◽  
Double Heterostructure ◽  
Organic Light ◽  
Hole Transporting ◽  
Hole Transporting Material

ABSTRACTWe have investigated the performance of a class of heterocycles, 5,10-dihetera- 5,10-dihydroindeno[3,2b]indenes, as hole transport agents in simple double heterostructure organic light-emitting diodes with tris(8-hydroxyquinoline)aluminum (Alq). The best of these materials, 5,10-dihydroindolo[3,2b]indole, yields devices with luminance and lifetimes comparable to those obtained using N,N′-di-(3-methylphenyl)-N,N′- diphenyl-4,4′-diaminobiphenyl (TPD) as a hole transporting material.

Fabrication of Micro-OLEDs by Room-temperature Curing Nanocontact-print Lithography Using DLC Molds

2012 ◽  
Vol 1511 ◽  
Author(s):  
Ippei Ishikawa ◽  
Keisuke Sakurai ◽  
Shuji Kiyohara ◽  
Taisuke Okuno ◽  
Hideto Tanoue ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Nanoimprint Lithography ◽  
Room Temperature ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Insulating Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Ito Glass

ABSTRACTThe microfabrication technologiesfor organic light-emitting devices (OLEDs) are essential to the fabrication of the next generation of light-emitting devices. The micro-OLEDs fabricated by room-temperature curing nanoimprint lithography (RTC-NIL) using diamond molds have been investigated. However, light emissions from 10 μm-square-dot OLEDs fabricated by the RTC-NIL method have not been uniform. Therefore, we proposed the fabrication of micro-OLEDs by room-temperature curing nanocontact-print lithography (RTC-NCL) using the diamond-like carbon (DLC) mold. The DLC molds used in RTC-NCL were fabricated by an electron cyclotron resonance (ECR) oxygen ion shower with polysiloxane oxide mask in electron beam (EB) lithography technology. The mold patterns are square and rectangle dots which has 10 µm-width, 10 µm-width and50 µm-length, respectively. The height of the patterns is 500 nm. The DLC molds were used to form the insulating layer of polysiloxane in RTC-NCL. We carried out the RTC-NCL process using the DLC mold under the following optimum conditions: 0.1 MPa-pressure for coating DLC mold with polysiloxane film, 2.1 MPa-pressure for transferring polysiloxane from DLC mold pattern to indium tin oxide (ITO) glass substrate. We deposited N, N'-Diphenyl -N, N'-di (m-tolyl)benzidine (TPD) [40 nm-thickness] as hole transport layer / Tris(8-quinolinolato)aluminum (Alq3) [40 nm-thickness] as electron transport layer / Al [200 nm-thickness] as cathode on ITO glass substrateas anode in this order. We succeeded in formation of the insulating layer with square and rectangle dots which has 10 µm-width,10 µm-width and 50 µm-length, and operation of micro-OLEDs by RTC-NIL using DLC molds.

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