Chemical Degradation in Organic Light‐Emitting Devices: Mechanisms and Implications for the Design of New Materials

Schmidbauer, Susanna; Hohenleutner, Andreas; König, Burkhard

doi:10.1002/adma.201205022

Cited by 320 publications

(314 citation statements)

References 72 publications

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“…Generally, OLED lifetimes have improved enough to enter the commercial market, and a review of some of the latest OLED materials shows a trend of more planar, stiffer molecules. 73 The progress in OLEDs further supports the idea that the general chemical stability of OSCs could also benefit from stiffer molecules with denser, more crystalline morphologies.…”

Section: Photochemical Reactions In the Absence Of Oxygen And Watermentioning

confidence: 62%

Molecular Packing and Arrangement Govern the Photo-Oxidative Stability of Organic Photovoltaic Materials

et al. 2015

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For long-term performance chemically robust materials are desired for organic solar cells (OSCs). Illuminating neat films of OSC materials in air and tracking the rate of absorption loss, or photobleaching, can quickly screen a material's photo-chemical stability. In this report, we photobleach neat films of OSC materials including polymers, solution-processed oligomers, solution-processed small molecules, and vacuum-deposited small molecules. Across the materials we test, we observe photobleaching rates that span seven orders of magnitude. Furthermore, we find that the film morphology of any particular material impacts the observed photobleaching rate, and that amorphous films photobleach faster than crystalline ones. In an extreme case, films of amorphous rubrene photobleach at a rate 2500 times faster than polycrystalline films. When we compare density to photobleaching rate, we find that stability increases with density. We also investigate the relationship between backbone planarity and chemical reactivity. The polymer PBDTTPD is more photostable than its more twisted and less ordered furan derivitative, PBDFTPD. Finally, we relate our work to what is known about the chemical stability of structural polymers, organic pigments, and organic light emitting diode materials. For the highest chemical stability, planar materials that form dense, crystalline film morphologies should be designed for OSCs.

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Section: Photochemical Reactions In the Absence Of Oxygen And Watermentioning

confidence: 62%

Molecular Packing and Arrangement Govern the Photo-Oxidative Stability of Organic Photovoltaic Materials

et al. 2015

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“…The CBP or TCTA exposed to negative polarons can be degraded due to low bond dissociation energy (BDE) under negative polarons. Comparing the BDE of C (sp 2 )—N (sp 2 ) bond of CBP and C (sp 2 )—N (sp 3 ) of TCTA, the BDE of former C—N bond (36.9 kcal mol −1 ) is higher than that of the latter C—N bond (35.6 kcal mol −1 ) under negative polarons, which stabilizes CBP:DBFTrz relative to TCTA:DBFTrz 18. Both electroplex and exciplex hosts can suppress electron injection into the hole transport type hosts, but the hole transport type host in the electroplex host can be more robust than that in the exciplex host because the hole transport type host in the electrolex has relatively weak hole transport character.…”

Section: Resultsmentioning

confidence: 97%

Electroplex as a New Concept of Universal Host for Improved Efficiency and Lifetime in Red, Yellow, Green, and Blue Phosphorescent Organic Light‐Emitting Diodes

et al. 2017

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A new concept of host, electroplex host, is developed for high efficiency and long lifetime phosphorescent organic light‐emitting diodes by mixing two host materials generating an electroplex under an electric field. A carbazole‐type host and a triazine‐type host are selected as the host materials to form the electroplex host. The electroplex host is found to induce light emission through an energy transfer process rather than charge trapping, and universally improves the lifetime of red, yellow, green, and blue phosphorescent organic light‐emitting diodes by more than four times. Furthermore, the electroplex host shows much longer lifetime than a common exciplex host. This is the first demonstration of using the electroplex as the host of high efficiency and long lifetime phosphorescent organic light‐emitting diodes.

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“…[9][10][11] However, phosphorescent materials incorporate expensive and scarce metals such as iridium or platinum and display significant degradation in the blue spectral region. 12,13 Metal-free, thermally activated delayed fluorescence (TADF) materials are considered to be third-generation emitters for OLEDs. [14][15][16][17][18] The basic requirement for efficient TADF is that the highest occupied and lowest unnocupied molecular orbital (HOMO and LUMO, respectively) are spacially separated to achieve a small energy gap between the lowest lying singlet and triplet states.…”

Section: Introductionmentioning

confidence: 99%

Pendant Homopolymer and Copolymers as Solution-Processable Thermally Activated Delayed Fluorescence Materials for Organic Light-Emitting Diodes

Ren

Nobuyasu²,

Dias³

et al. 2016

Macromolecules

148

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This study reports a series of polymers with an insulating backbone and varying ratios of 2-(10H-phenothiazin-10-yl)dibenzothiophene-S,S-dioxide as a pendant TADF unit. Steady-state and time-resolved fluorescence spectroscopic data confirm the efficient TADF properties of the polymers. Styrene, as a co-monomer, is shown to be a good dispersing unit for the TADF groups, by greatly supressing the internal conversion and triplet-triplet annihilation.Increasing the styrene content within the copolymers results in relatively high triplet energy, small energy splitting between the singlet and triplet states (E ST ) and a strong contribution from delayed fluorescence to the overall emission. Green emitting OLED devices employing these polymers as spin-coated emitting layers give high performance, which is dramatically enhanced in the copolymers compared to the homopolymer. Within the series, Copo1 with a regiorandom ratio of 37% TADF units : 63% styrene units displays the best performance with a maximum external quantum efficiency (EQE) of 20.1% and EQE at 100 cd m -2 of 5.3%.2

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Chemical Degradation in Organic Light‐Emitting Devices: Mechanisms and Implications for the Design of New Materials

Cited by 320 publications

References 72 publications

Molecular Packing and Arrangement Govern the Photo-Oxidative Stability of Organic Photovoltaic Materials

Molecular Packing and Arrangement Govern the Photo-Oxidative Stability of Organic Photovoltaic Materials

Electroplex as a New Concept of Universal Host for Improved Efficiency and Lifetime in Red, Yellow, Green, and Blue Phosphorescent Organic Light‐Emitting Diodes

Pendant Homopolymer and Copolymers as Solution-Processable Thermally Activated Delayed Fluorescence Materials for Organic Light-Emitting Diodes

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