Effect of metal films on the photoluminescence and electroluminescence of conjugated polymers

Becker, Heinrich; Burns, S. E.; Friend, Richard H.

doi:10.1103/physrevb.56.1893

Cited by 276 publications

(202 citation statements)

References 41 publications

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“…External quantum efficiencies (EQEs) of 30% have been reported recently [1][2][3][4][5][6] ; this is considered to be the light-outcoupling efficiency limit of phosphorescent OLEDs under isotropically oriented transition dipole moments 4 . It has long been recognized that orienting the transition dipole moment of an emitter along the horizontal direction (parallel to the substrate) can enhance the outcoupling efficiency beyond that achieved under isotropic orientation, as demonstrated in polymer-based and vacuumevaporated fluorescent molecule-based OLEDs [7][8][9][10][11][12][13] . Nonetheless, the orientation of the transition dipole moments of iridium complexes used as phosphorescent emitters in efficient OLEDs is typically considered to be isotropic because they are near-globular and small enough to have configurational diversity in their orientational states.…”

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confidence: 99%

Phosphorescent dye-based supramolecules for high-efficiency organic light-emitting diodes

et al. 2014

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Organic light-emitting diodes (OLEDs) are among the most promising organic semiconductor devices. The recently reported external quantum efficiencies (EQEs) of 29-30% for green and blue phosphorescent OLEDs are considered to be near the limit for isotropically oriented iridium complexes. The preferred orientation of transition dipole moments has not been thoroughly considered for phosphorescent OLEDs because of the lack of an apparent driving force for a molecular arrangement in all but a few cases, even though horizontally oriented transition dipoles can result in efficiencies of over 30%. Here we use quantum chemical calculations to show that the preferred orientation of the transition dipole moments of heteroleptic iridium complexes (HICs) in OLEDs originates from the preferred direction of the HIC triplet transition dipole moments and the strong supramolecular arrangement within the co-host environment. We also demonstrate an unprecedentedly high EQE of 35.6% when using HICs with phosphorescent transition dipole moments oriented in the horizontal direction.

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confidence: 99%

Phosphorescent dye-based supramolecules for high-efficiency organic light-emitting diodes

et al. 2014

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“…These experiments demonstrated an ef®cient quenching of the EL over a distance of about 20 nm in a region adjacent to the cathode. Furthermore, from photoluminescence (PL) experiments an effective quenching region of nearly 20 nm has been obtained for cyano derivatives of PPV [13]. It should be noted that in our model, the quenching region abruptly ends at a distance L q , whereas experiments [12,13] show a more gradual increase of the light intensity with increasing distance from the cathode.…”

Section: Methodsmentioning

confidence: 66%

Performance of a polymer light-emitting diode with enhanced charge carrier mobility

et al. 2001

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“…Orientation of the transition dipole moments of a light-emitting molecule plays a critical role on the performance of OLEDs. 9,14,20,21 Higher light out-coupling efficiency and EQE have been achieved when the emitters were oriented parallel to the substrates. Our ellipsometry results imply that the molecular orientation of the heptafluorene neat film should have only small effects on the OLEDs properties.…”

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confidence: 99%

Horizontal molecular orientation in solution-processed organic light-emitting diodes

Zhao

Komino

Inoue

et al. 2015

Applied Physics Letters

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Horizontal orientation of the emission transition dipole moments achieved in glassy vapor-deposited organic thin films leads to an enhancement of the light out-coupling efficiency in organic light-emitting diodes (OLEDs). Here, our combined study of variable angle spectroscopic ellipsometry and angle dependent photoluminescence demonstrates that such a horizontal orientation can be achieved in glassy spin-coated organic films based on a composite blend of a heptafluorene derivative as a dopant and a 4,4′-bis(N-carbazolyl)-1,1′-biphenyl as a host. Solution-processed fluorescent OLEDs with horizontally oriented heptafluorene emitters were then fabricated and emitted deep blue electroluminescence with an external quantum efficiency as high as 5.3%.

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Effect of metal films on the photoluminescence and electroluminescence of conjugated polymers

Cited by 276 publications

References 41 publications

Phosphorescent dye-based supramolecules for high-efficiency organic light-emitting diodes

Phosphorescent dye-based supramolecules for high-efficiency organic light-emitting diodes

Performance of a polymer light-emitting diode with enhanced charge carrier mobility

Horizontal molecular orientation in solution-processed organic light-emitting diodes

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