Studies on the photodegradation of red, green and blue phosphorescent OLED emitters

Schmidbauer, Susanna; Hohenleutner, Andreas; König, Burkhard

doi:10.3762/bjoc.9.245

Cited by 43 publications

(34 citation statements)

References 26 publications

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“…[35][36][37][38] It is discovered that the exciton-induced bond rupture and subsequent reactions play important role during the degradation process. Recently, researchers in the fi eld of organic electroluminescence have paid attention to investigate the degradation process of organic emitters under electrical driving.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, researchers in the fi eld of organic electroluminescence have paid attention to investigate the degradation process of organic emitters under electrical driving. [35][36][37][38] It is discovered that the exciton-induced bond rupture and subsequent reactions play important role during the degradation process. [ 39,40 ] It is also recommended that rigidifying of the molecular structure can effi ciently reduce the degradation reactions due to decreased rotational fl exibility.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Antiphotobleaching: A Type of Structurally Rigid Chromophore Ready for Constructing Highly Luminescent and Highly Photostable Europium Complexes

Wei

Zhao

Chen

et al. 2016

Adv Funct Materials

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2085wileyonlinelibrary.com found to be effective in light harvesting and sensitizing the lanthanide emission through the "antenna effect." [1][2][3] Bright luminescence can be detected even if the LLCs are diluted into extremely low concentration. Therefore, LLCs are very promising for a wide range of applications, such as bioimaging, [ 4 ] immunoassay, [ 5 ] sensors, [ 6 ] light conversion fi lms for photovoltaic devices, [ 7,8 ] light emitting diode (LED) phosphors, [ 9 ] and organic LEDs (OLEDs). [ 2,10 ] Large quantities of LLCs have been synthesized and tremendous progress has been made to improve their luminescent properties. From the standpoint of materials engineering, convenient synthesis, high emission quantum yield (>0.5), and excellent photostability (no degradation >20 h under UV/blue excitation) are quite essential for successful application of such materials. [ 11 ] Up to now, photoinstability has become the major obstacle that limits the applicability of LLCs. In most conditions, lanthanide complexes (e.g., Eu 3+ and Tb 3+ chelates) harvest excitation energy from UV/blue light. However, organic ligands in the compounds are likely to be destroyed by the high energy photons. This photodegradation process has been observed in various kinds of, most currently known, lanthanide complexes. [12][13][14][15][16][17][18][19] Taking the most commonly used β-diketone derivatives as an example, although ligands like 2-thenoyltrifl uoroacetonate (TTA) and 1,3-diphenylpropane-1,3-dionate (DBM) are widely utilized for complexation of Eu 3+ ion and constructing luminescent material with high photoluminescence quantum yield (PLQY), [ 20,21 ] LLCs based on such kind of ligands suffer from serious photodegradation upon UV exposure, showing continuous decrease of the emission intensity. [ 22,23 ] To overcome this shortcoming, lanthanide complexes have been incorporated into polymers, [ 24,25 ] ionic liquids, [ 12 ] organic-inorganic hybrid systems, [ 13,19,[26][27][28][29][30][31] and so on, where the matrix plays the role of a protective cage for the complexes, strongly decreasing the UV degradation rate. However, such techniques always demand complicated synthesis process and may cause decreased PLQYs, [ 32 ] and these roles are still uncertain to remain effective for long enough time toward practical Antiphotobleaching is a critical challenge in the fi eld of luminescent lanthanide complexes (LLCs) as well as in many disciplines concerning organic luminescent processes. In this work, a type of structurally rigid organic ligand, 4-hydroxy-1,5-naphthyridine (ND), is developed, which can not only effi ciently sensitize the europium emission but also demonstrate unique photostability. A series of ND derivatives with different substituent groups are synthesized and their singlet and triplet excited state energy levels are systematically investigated. Photophysical characterizations of the corresponding europium complexes reveal that the sensitization effi ciencies ( η sens ) are close to 100% and the total photolumines...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antiphotobleaching: A Type of Structurally Rigid Chromophore Ready for Constructing Highly Luminescent and Highly Photostable Europium Complexes

Wei

Zhao

Chen

et al. 2016

Adv Funct Materials

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“…However, the hot excited states generated by triplet–triplet annihilation of blue emitters possess an energy of ≈6 eV,23 meaning that these T d concepts are not suitable in estimating the material stability of blue emitters. To cope with this deficiency and provide better assessment on material stability, there are a number of literature reports on the use of either 400 nm LED24 or UV irradiation25 to test photostability of OLED emitters in solution and in a solid organic matrix. The photostabilities studies of bis‐tridentate Ir(III) complexes remain rare in comparison to the corresponding tris ‐bidentate phosphors.…”

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confidence: 99%

Bis‐Tridentate Iridium(III) Phosphors with Very High Photostability and Fabrication of Blue‐Emitting OLEDs

et al. 2018

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Sky‐blue and blue‐emitting, carbazolyl functionalized, bis‐tridentate Ir(III) phosphors Cz‐1–Cz‐3 with bright emission and short radiative lifetime are successfully synthesized in a one‐pot manner. They exhibit very high photostability against UV–vis irradiation in degassed toluene, versus both green and true‐blue‐emitting reference compounds, i.e., fac‐[Ir(ppy)3] and mer‐[Ir(pmp)3]. Organic light‐emitting diodes (OLEDs) based on Cz‐2 exhibit maximum external quantum efficiency (EQE) of 21.6%, EQE of 15.1% at 100 cd m−2, and with CIEx , y coordinates of (0.17, 0.25). This study provides a conceptual solution to the exceedingly stable and efficient blue phosphor. It is promising that long lifespan blue OLED based on these emitters can be attained with further engineering of devices suitable for commercial application.

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“…It is known that organic materials degrade easily when light, moisture and/or oxygen are present simultaneously [1][2][3][4][5]; this is the reason for which organic electronic devices such as organic light emitting diodes (OLEDs) need to be encapsulated. Most of the studies regarding the device degradation are related to the operational degradation, i.e.…”

Section: Introductionmentioning

confidence: 99%

Fast photoluminescence quenching in thin films of 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl exposed to air

Tomović

Jovanović

Đurišić

et al. 2015

Journal of Luminescence

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Studies on the photodegradation of red, green and blue phosphorescent OLED emitters

Cited by 43 publications

References 26 publications

Antiphotobleaching: A Type of Structurally Rigid Chromophore Ready for Constructing Highly Luminescent and Highly Photostable Europium Complexes

Antiphotobleaching: A Type of Structurally Rigid Chromophore Ready for Constructing Highly Luminescent and Highly Photostable Europium Complexes

Bis‐Tridentate Iridium(III) Phosphors with Very High Photostability and Fabrication of Blue‐Emitting OLEDs

Fast photoluminescence quenching in thin films of 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl exposed to air

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