A new tricarbazole phosphine oxide bipolar host for efficient single-layer blue PhOLED

Chang, Hsiu-Ju; Tsai, Christina W.; Chang, Chien-Ping; Chen, Nien-Po; Wong, Ken‐Tsung; Hung, Wen‐Yi; Chen, Shou-Wei

doi:10.1016/j.orgel.2011.08.030

Cited by 37 publications

(12 citation statements)

References 32 publications

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“…We now turn from the aryl SO 2 based molecules to the aryl PO based analogs, which have also been widely used to develop high-efficiency blue-emitting host materials. [34][35][36][37][38][39] In the case of TPPO, the initial photodegradation step under UV irradiation has been shown to correspond to the homolytic dissociation of the relatively weak P-C P bond. 18,19 Optimized bond lengths for the S 0 and the T 1 states of TPPO are depicted in Figure 7.…”

Section: B) Relative Photostabilities Of Tppo and Dpsomentioning

confidence: 99%

“…Both the sulfonyl and phosphoryl groups have strong inductive electronwithdrawing character, and can energetically stabilize the lowest unoccupied molecular orbital (LUMO) of the -conjugated molecular cores to afford electron-transport materials. 33 Combined with their high triplet energies, aryl SO 2 and aryl PO derivatives have been used in the development of host materials that inhibit self-quenching of the light-emitting guests in both blue phosphorescent [34][35][36][37][38][39][40] and TADF OLEDs. [41][42][43] In addition, such aryl SO 2 and aryl PO based host materials exhibit good thermal stabilities.…”

Section: Introductionmentioning

confidence: 99%

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Chemical Stabilities of the Lowest Triplet State in Aryl Sulfones and Aryl Phosphine Oxides Relevant to OLED Applications

Hong

Scarpaci

et al. 2019

Chem. Mater.

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Aryl sulfones and phosphine oxides are widely used as molecular building blocks for host materials in the emissive layers of organic light-emitting diodes. In this context, the chemical stability of such molecules in the triplet state is of paramount concern to long-term device performance. Here, we explore the triplet excited-state (T 1) chemical stabilities of aryl sulfonyl and aryl phosphoryl molecules by means of UV absorption spectroscopy and density functional theory calculations. Both the sulfur-carbon bonds of the aryl sulfonyl molecules and the phosphorus-carbon bonds of aryl phosphoryl derivatives are significantly more vulnerable to dissociation in the T 1 state when compared to the ground (S 0) state. Although the vertical S 0 →T 1 transitions correspond to non-bonding→-orbital transitions, geometry relaxations in the T 1 state lead to -* character over the respective sulfur-carbon or phosphorus-carbon bond, a result of significant electronic state mixing, which facilitates bond dissociation. Both the activation energy for bond dissociation and the bond dissociation energy in the T 1 state are found to vary linearly with the adiabatic T 1-state energy. Specifically as T 1 becomes more energetically stable, the activation energy becomes larger, and dissociation becomes less likely, i.e., more endothermic or less exothermic. While substitutions of electron-donating or accepting units onto the aryl sulfones and aryl phosphine oxides have only marginal influence on the dissociation reactions, extension of the -conjugation of the aryl groups leads to a significant reduction in the triplet energy and a considerable enhancement in the T 1-state chemical stabilities.

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Section: B) Relative Photostabilities Of Tppo and Dpsomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemical Stabilities of the Lowest Triplet State in Aryl Sulfones and Aryl Phosphine Oxides Relevant to OLED Applications

Hong

Scarpaci

et al. 2019

Chem. Mater.

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“…More importantly, its triplet energy E T (2.55 eV) 40 is too low for sky-blue phosphors such as FIrpic. 41 Phosphine oxide (PO) 15,16,[42][43][44][45][46][47][48][49] and sulfone (SO 2 ) 50, 51 derivatives with high triplet energy have emerged as host materials for blue electrophosphorescence and have also been successfully utilized in OLEDs. For example, 4,4'-bis(diphenylphosphine oxide) biphenyl (PO1), synthesized by Sapochak and co-workers, 49 has a triplet exciton energy (2.72 eV) higher than CBP through substitution of the carbazoles with diphenylphosphoryl (Ph 2 P=O) groups; the reason is that the P=O group prevents electronic communication between the central diphenyl core and the outer phenyl groups.…”

Section: Degradation In Host Moleculesmentioning

confidence: 99%

Theoretical investigation of the degradation mechanisms in host and guest molecules used in OLED active layers

2014

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A feature of OLEDs that has to date received little attention is the prediction of the stability of the molecules involved in the electrical and optical processes. Here, we present computational results intended to aid in the development of stable systems. We identify degradation pathways and define new strategies to guide the synthesis of stable materials for OLED applications for both phosphorescent emitters and organic host materials. The chemical reactivity of these molecules in the active layers of the devices is further complicated by the fact that, during operation, they can be either oxidized or reduced (as they localize a hole or an electron) in addition to forming both singlet and triplet excitons.

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“…Another potential application for OLEDs is to be introduced for solid-state lighting in the near future [1][2][3][4][5][6][7]. In the past two decades, tremendous efforts have been spent to improve the performance of OLEDs such as developing efficient phosphorescent materials which can harvest both singlet and triplet excitons [8][9][10][11][12][13], exploiting various device configurations to efficiently utilize excitons [2][3][4]14]. Generally speaking, in order to obtain high efficiency, OLEDs always adopt multilayer structure including electron or hole/exciton blocking layer to avoid exciton quenching.…”

Section: Introductionmentioning

confidence: 99%

Highly efficient orange and white phosphorescent organic light-emitting devices with simplified structure

Xue

Han

Chen

et al. 2015

Organic Electronics

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A new tricarbazole phosphine oxide bipolar host for efficient single-layer blue PhOLED

Cited by 37 publications

References 32 publications

Chemical Stabilities of the Lowest Triplet State in Aryl Sulfones and Aryl Phosphine Oxides Relevant to OLED Applications

Chemical Stabilities of the Lowest Triplet State in Aryl Sulfones and Aryl Phosphine Oxides Relevant to OLED Applications

Theoretical investigation of the degradation mechanisms in host and guest molecules used in OLED active layers

Highly efficient orange and white phosphorescent organic light-emitting devices with simplified structure

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