Electroluminescent Properties of Spiro[fluorene-benzofluorene]-Containing Blue Light Emitting Materials

doi:10.5012/bkcs.2009.30.4.863

Cited by 12 publications

(1 citation statement)

References 20 publications

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“…In 2002, Wu and his colleagues 12 used 2,7bis[2-(4-tert-butylphenyl)pyrimidine-5-yl-9,9′-spirobifluorene as a host of perylene in a blue OLED and obtained a maximum brightness of 80000 cd•m -2 . Lee et al 21 fabricated a simple blue device using 2,7-bis(diphenylphosphoryl)-9,9′-spirobi[fluorene] as a host material and realized a quantum efficiency of as high as 20.3% without any LiF electron injection layer. Recently, Wang′s team 22 synthesized 3,6-di(9H-carbazol-9-yl)-9,9′-spirobi[fluorene], with which as a host they exhibited a OLED with a very low turnon voltage of 2.8 V and a high current efficiency of 34.2 cd•A -1 .…”

Section: Introductionmentioning

confidence: 99%

One-Step Synthesis of Spirobi[fluorene] and Spiro[fluorene-9,9′-xanthene] Derivatives and Their Applications in Organic Light-Emitting Devices: Performance Enhancement and Related Optical Phenomena

Guan¹,

Song²,

Sun³

et al. 2016

Acta Physico-Chimica Sinica

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Section: Introductionmentioning

confidence: 99%

One-Step Synthesis of Spirobi[fluorene] and Spiro[fluorene-9,9′-xanthene] Derivatives and Their Applications in Organic Light-Emitting Devices: Performance Enhancement and Related Optical Phenomena

Guan¹,

Song²,

Sun³

et al. 2016

Acta Physico-Chimica Sinica

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Versatile p‐Type Chemical Doping to Achieve Ideal Flexible Graphene Electrodes

Han

Kwon

et al. 2016

Angewandte Chemie

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Abstract:We report effective solution-processed chemical ptype doping of graphene using trifluoromethanesulfonic acid (CF 3 SO 3 H, TFMS), that can provide essential requirements to approach an ideal flexible graphene anode for practical applications:i )h igh optical transmittance,i i) lows heet resistance (70 %d ecrease), iii)h igh work function (0.83 eV increase), iv) smooth surface,a nd iv) air-stability at the same time.The TFMS-doped graphene formed nearly ohmic contact with ac onventional organic hole transporting layer,a nd ag reen phosphorescent organic light-emitting diode with the TFMS-doped graphene anode showed lower operating voltage, and higher device efficiencies (104. The widely used indium tin oxide (ITO) transparent electrode is not appropriate for use in flexible electronics, because it is brittle,i ncreasingly expensive,a nd causes diffusion of impurities into devices. [1][2][3] Therefore,f lexible transparent electrodes must be developed before the use of flexible electronics is practical. Graphene is aone atom thick sheet of sp 2 hybridized carbon atoms that has unique electrical properties and mechanical robustness.[2, 4-11] Therefore,m any researchers have explored ways to use graphene electrodes in flexible organic optoelectronics. [2,[12][13][14][15][16][17][18][19][20][21][22] However, the pristine graphene has suffered from two inherent major problems:1)The first disadvantage comes from its low charge carrier density.T herefore,t he pristine graphene has much higher sheet resistance (200-300 W sq À1 )t han does ITO ( % 10 W sq À1 ), which resulted in high operating voltage and poor luminous power efficiency (PE)inorganic light-emitting diodes (OLEDs), [15,16] and thus graphene requires an additional doping process to improve the charge carrier concentration and the electrical conductivity. [2,[20][21][22][23][24][25][26][27] 2) Thep ristine graphenes work function (WF = 4.4 eV) is much lower than that of ITO( 4.8 eV).[2] Thel ow WF of the pristine graphene significantly limits the hole injection from the graphene anode to an overlying organic layers in OLEDs. [2,15,16] Thenitric acid (HNO 3 )and the gold (III) chloride (AuCl 3 )have been widely used as chemical p-type dopants for graphene to reduce sheet resistance (R s ). [2,6,[21][22][23] However,these conventional chemical dopants cause instability problems:t he HNO 3 gradually evaporates from the graphene in the ambient condition due to its volatility,thereby causing gradual decrease of electrical conductivity of the p-doped graphene and its device; [2a, 22-24] TheA uCl 3 leaves 50-100 nm Au particles on the graphene surface,w hich degrades device efficiencya nd stability increasing current leakage in the thin film devices.[2a] Therefore,tofabricate ideal graphene anodes for organic optoelectronics needs aversatile p-type doping method that can meet essential requirements at the same time:i )h igh optical transmittance (OT), ii)the low R s comparable to that of ITO, iii)t he high surface WF that can effectively reduce the hole i...

show abstract

Versatile p‐Type Chemical Doping to Achieve Ideal Flexible Graphene Electrodes

Han

Kwon

et al. 2016

Angew Chem Int Ed

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We report effective solution-processed chemical p-type doping of graphene using trifluoromethanesulfonic acid (CF3 SO3 H, TFMS), that can provide essential requirements to approach an ideal flexible graphene anode for practical applications: i) high optical transmittance, ii) low sheet resistance (70 % decrease), iii) high work function (0.83 eV increase), iv) smooth surface, and iv) air-stability at the same time. The TFMS-doped graphene formed nearly ohmic contact with a conventional organic hole transporting layer, and a green phosphorescent organic light-emitting diode with the TFMS-doped graphene anode showed lower operating voltage, and higher device efficiencies (104.1 cd A(-1) , 80.7 lm W(-1) ) than those with conventional ITO (84.8 cd A(-1) , 73.8 lm W(-1) ).

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Electroluminescent Properties of Spiro[fluorene-benzofluorene]-Containing Blue Light Emitting Materials

Cited by 12 publications

References 20 publications

One-Step Synthesis of Spirobi[fluorene] and Spiro[fluorene-9,9′-xanthene] Derivatives and Their Applications in Organic Light-Emitting Devices: Performance Enhancement and Related Optical Phenomena

One-Step Synthesis of Spirobi[fluorene] and Spiro[fluorene-9,9′-xanthene] Derivatives and Their Applications in Organic Light-Emitting Devices: Performance Enhancement and Related Optical Phenomena

Versatile p‐Type Chemical Doping to Achieve Ideal Flexible Graphene Electrodes

Versatile p‐Type Chemical Doping to Achieve Ideal Flexible Graphene Electrodes

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