LIGHT-EMITTING PROPERTIES OF FLUORENE-BASED COPOLYMERS

2004 ◽  
Vol 13 (03n04) ◽  
pp. 637-642 ◽  
Author(s):  
DO-HOON HWANG ◽  
JONG-DON LEE ◽  
MOO-JIN PARK ◽  
JI-HOON LEE ◽  
CHANG-HEE LEE
Keyword(s):  
Charge Transport ◽  
Random Copolymers ◽  
Device Performance ◽  
Visible Absorption ◽  
Light Emitting ◽  
Hole Transporting ◽  
Uv Visible ◽  
Pl Emission

A series of random copolymers of 2,7-dibromo-9,9-bis(4′-n-octyloxyphenyl) fluorene (BOPF) and 2,7-dibromo-N-(2′-ethylhexyl)carbazole (EHC) were synthesized through Ni (0)-mediated polymerization. Carbazole comonomer was introduced to improve the hole-transporting properties of PBOPF. The synthesized poly(BOPF-co-EHC)s showed similar UV-visible absorption and PL emission to PBOPF. EL devices were fabricated in an ITO/PEDOT/polymer/Ca/Al configuration. EL devices which used copolymers showed improved device performance over devices which used PBOPF homopolymers due to a more balanced charge transport.

EL Properties of Polyfluorene Copolymers Containing Hole-Transporting Carbazole Group

2003 ◽  
Vol 771 ◽  
Author(s):  
Do-Hoon Hwang ◽  
Jong-Don Lee ◽  
Moo-Jin Park ◽  
Ji-Hoon Lee ◽  
Chang-Hee Lee
Keyword(s):  
Charge Transport ◽  
Random Copolymers ◽  
Device Performance ◽  
Excimer Emission ◽  
Visible Absorption ◽  
Light Emitting ◽  
Hole Transporting ◽  
Uv Visible ◽  
Pl Emission ◽  
Carbazole Group

AbstractAn alkoxyphenyl substitutued new polyfluorene derivative, poly(9,9-bis(4'-n-octyloxyphenyl) fluorene) (PBOPF) was synthesized through Ni(0) mediated polymerization. Blue light-emitting PBOPF shows peak PL at 426 nm. No significant excimer emission was observed even after annealing the polymer film at 100 oC for 2h. Aseries of random copolymers of 2,7-dibromo-9,9-bis(4'-n-octyloxyphenyl)) fluorene (BOPF) and 2,7-dibromo-N-(2'-ethylhexyl)carbazole (EHC) were also synthesized through Ni(0) mediated polymerization. Carbazole comonomer was introduced to improve hole-transporting properties of PBOPF. The synthesized poly(BOPF-co-EHC)s showed similar UV-visible absorption and PL emission to PBOPF. EL devices were fabricated in an ITO/PEDOT/polymer/Ca/Al configuration. The EL devices using copolymers showed improved device performance than the device using PBOPF homopolymer due to a more balanced charge transport.

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).

Influence of hole transporting material on device performance in organic light-emitting diode

2000 ◽  
Vol 363 (1-2) ◽  
pp. 290-293 ◽  
Author(s):  
Shizuo Tokito ◽  
Koji Noda ◽  
Kou Shimada ◽  
Shin-ichiro Inoue ◽  
Makoto Kimura ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Device Performance ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
Hole Transporting ◽  
Hole Transporting Material

scholarly journals Improvement in hole transporting ability and device performance of quantum dot light emitting diodes

2020 ◽  
Vol 2 (1) ◽  
pp. 401-407
Author(s):  
Pei-Chieh Chiu ◽  
Sheng-Hsiung Yang
Keyword(s):  
Quantum Dot ◽  
Light Emitting Diodes ◽  
Device Performance ◽  
Light Emitting ◽  
Hole Transporting

A new additive BYK-P105 was blended with PEDOT:PSS as the HTL to improve the device performance of QLEDs.

Hole-transporting materials for low donor content organic solar cells: Charge transport and device performance

2020 ◽  
Vol 76 ◽  
pp. 105480 ◽  
Author(s):  
Wei Jiang ◽  
Chen Tao ◽  
Martin Stolterfoht ◽  
Hui Jin ◽  
Meera Stephen ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Transport ◽  
Organic Solar Cells ◽  
Device Performance ◽  
Hole Transporting ◽  
Hole Transporting Materials

scholarly journals Position Effects of Metal Nanoparticles on the Performance of Perovskite Light-Emitting Diodes

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 993
Author(s):  
Chen-Min Yang ◽  
Fang-Chung Chen
Keyword(s):  
Metal Nanoparticles ◽  
Light Emitting Diodes ◽  
Device Performance ◽  
Perovskite Layer ◽  
Position Effects ◽  
Au Nps ◽  
Light Emitting ◽  
Hole Transporting ◽  
Near Future ◽  
Luminance Efficiency

Metal nanoparticles have been widely used for improving the efficiencies of many optoelectronic devices. Herein, position effects of gold nanoparticles (Au NPs) on the performance of perovskite light-emitting diodes (PeLEDs) are investigated. Amphiphilic Au NPs are synthesized so that they can be incorporated into different layers of the PeLEDs to enhance device efficiencies. The photoluminescent (PL) studies indicate apparent position effects; the strongest PL intensity occurs when the NPs are directly blended with the light-emitting perovskite layer. In contrast, the PeLEDs exhibit the highest luminance efficiency while the Au NPs are placed in the hole-transporting layer. The direct blending of the NPs in the perovskite layer might affect the electrical properties, resulting in inferior device performance. The results reported herein can help to understand the enhancing mechanism of the PeLEDs and may also lead to even better efficiencies in the near future.

Synthesis and Characterization of Highly Twisted and Bulky Tetraoctyloxybiphenyl-Containing Polyfluorene Copolymers: Toward Efficient Blue Polymer Light Emitting Diodes

2007 ◽  
Vol 7 (11) ◽  
pp. 3810-3814
Author(s):  
In-Nam Kang ◽  
Sung-Hwan Lim ◽  
Jong-Wook Park ◽  
Kyoung-Soo Kim ◽  
Min-Chul Chung ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diodes ◽  
Blue Emission ◽  
Random Copolymers ◽  
Synthesis And Characterization ◽  
Coupling Reactions ◽  
Light Emitting ◽  
Polymer Light Emitting Diodes ◽  
Pl Emission

We have synthesized new blue light emitting random copolymers, poly(9,9′-n-dioctylfluorene-co-2,2′,6,6′-tetraoctyloxybiphenyl-3,3′-diyl)s (PFTOBPs), via Ni(0)-mediated coupling reactions. The PL emission peaks of the resulting copolymers closely resembled those of the polyfluorene (PF) homopolymer. The EL devices fabricated using these copolymers exhibited highly pure blue emission with approximate 1931 CIE coordinates of (0.15, 0.15) at 1000 cd/m2. The maximum brightnesses ranged from 2000 to 12000 cd/m2 with maximum efficiencies from 0.53 to 0.97 cd/A. The efficiencies were found to increase as the fraction of TOBP in the copolymers was increased, which may result the inhibition of exciton quenching that is produced by the introduction of the highly twisted and bulky TOBP moieties into the copolymers.

Synthesis and Characterization of Highly Twisted and Bulky Tetraoctyloxybiphenyl-Containing Polyfluorene Copolymers: Toward Efficient Blue Polymer Light Emitting Diodes

2007 ◽  
Vol 7 (11) ◽  
pp. 3810-3814 ◽  
Author(s):  
In-Nam Kang ◽  
Sung-Hwan Lim ◽  
Jong-Wook Park ◽  
Kyoung-Soo Kim ◽  
Min-Chul Chung ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diodes ◽  
Blue Emission ◽  
Random Copolymers ◽  
Synthesis And Characterization ◽  
Coupling Reactions ◽  
Light Emitting ◽  
Polymer Light Emitting Diodes ◽  
Pl Emission

We have synthesized new blue light emitting random copolymers, poly(9,9′-n-dioctylfluorene-co-2,2′,6,6′-tetraoctyloxybiphenyl-3,3′-diyl)s (PFTOBPs), via Ni(0)-mediated coupling reactions. The PL emission peaks of the resulting copolymers closely resembled those of the polyfluorene (PF) homopolymer. The EL devices fabricated using these copolymers exhibited highly pure blue emission with approximate 1931 CIE coordinates of (0.15, 0.15) at 1000 cd/m2. The maximum brightnesses ranged from 2000 to 12000 cd/m2 with maximum efficiencies from 0.53 to 0.97 cd/A. The efficiencies were found to increase as the fraction of TOBP in the copolymers was increased, which may result the inhibition of exciton quenching that is produced by the introduction of the highly twisted and bulky TOBP moieties into the copolymers.

scholarly journals Polymeric Hole Transport Materials for Red CsPbI3 Perovskite Quantum-Dot Light-Emitting Diodes

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 896
Author(s):  
Zong-Liang Tseng ◽  
Shih-Hung Lin ◽  
Jian-Fu Tang ◽  
Yu-Ching Huang ◽  
Hsiang-Chih Cheng ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Comparative Study ◽  
External Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Device Performance ◽  
Light Emitting ◽  
Device Structures ◽  
Hole Transporting ◽  
Hole Transporting Materials

In this study, the performances of red CsPbI3-based all-inorganic perovskite quantum-dot light-emitting diodes (IPQLEDs) employing polymeric crystalline Poly(3-hexylthiophene-2,5-diyl) (P3HT), poly(9-vinycarbazole) (PVK), Poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidine (Poly-TPD) and 9,9-Bis[4-[(4-ethenylphenyl)methoxy]phenyl]-N2,N7-di-1-naphthalenyl-N2,N7-diphenyl-9H-fluorene-2,7-diamine (VB-FNPD) as the hole transporting layers (HTLs) have been demonstrated. The purpose of this work is an attempt to promote the development of device structures and hole transporting materials for the CsPbI3-based IPQLEDs via a comparative study of different HTLs. A full-coverage quantum dot (QD) film without the aggregation can be obtained by coating it with VB-FNPD, and thus, the best external quantum efficiency (EQE) of 7.28% was achieved in the VB-FNPD device. We also reported a standing method to further improve the degree of VB-FNPD polymerization, resulting in the improved device performance, with the EQE of 8.64%.

scholarly journals White light emitting dysprosium doped lanthanum oxalate single crystals

2021 ◽  
Vol 2070 (1) ◽  
pp. 012097
Author(s):  
S Vandana ◽  
Cyriac Joseph
Keyword(s):  
Single Crystals ◽  
White Light ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Visible Absorption ◽  
Light Emitting ◽  
X Ray ◽  
Uv Visible ◽  
Thermal Stability Of

Abstract Single crystals of Lanthanum oxalate [La2 (C2O4)3]1OH2O and Dy3+ doped Lanthanum oxalate [La2-xDyx (C2O4)3]10H2O with x=0.1, 0.15, 0.2 were grown by gel method and characterised by X-ray powder diffraction analysis. Thermal stability of sample was investigated by thermo gravimetric analysis. UV-Visible absorption and photo-luminescent studies were also conducted. The emission spectrum on exciting at 271nm and 364 nm were recorded in which Dy3+ ions showed four emission bands at positions 458nm (blue), 478 nm (blue), 572 nm (yellow) and 655 nm (red) corresponding to transitions 4I15/2→ 6H15/2, 4F9/2→ 6H15/2, 4F9/2→ 6H13/2 and 4F9/2→ 6H11/2 respectively. The CIE coordinates, colour purity and CCT values were calculated, and all these parameters show that Dy3+ doped lanthanum oxalate single crystals are suitable candidates for white light emitting applications.

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