A Novel Family of Boron‐Containing Hole‐Blocking Amorphous Molecular Materials for Blue‐ and Blue–Violet‐Emitting Organic Electroluminescent Devices

Kinoshita, Motoi; Kita, Hiroshi; Shirota, Yasuhiko

doi:10.1002/adfm.200290007

Cited by 102 publications

(68 citation statements)

References 45 publications

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“…[3][4][5][6][7] Owing to the above-mentioned features, TABs are used as emitting and/or charge-transport materials in optoelectronic devices, such as organic light-emitting diodes (OLED). [1,2,[8][9][10] In particular the combination of TABs with Abstract: We synthesized a series of amino substituted triarylboranes (TABs) 1-3 by copper(i)-catalyzed cross-coupling reactions. The title compounds were investigated by means of cyclic voltammetry (CV) and UV-visible absorption and fluorescence spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Electrochemistry and Photophysics of Donor‐Substituted Triarylboranes: Symmetry Breaking in Ground and Excited State

Stahl

Lambert

Kaiser

et al. 2006

Chemistry A European J

161

152

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We synthesized a series of amino substituted triarylboranes (TABs) 1-3 by copper(I)-catalyzed cross-coupling reactions. The title compounds were investigated by means of cyclic voltammetry (CV) and UV-visible absorption and fluorescence spectroscopy. Electrochemical oxidation of tris(4-carbazolyl-2,6-dimethylphenyl)borane (3) leads to the formation of an electroactive polymer film on the electrode surface. The charge-transfer (CT) absorption band of all three TABs shows a pronounced negative solvatochromism, while the emission is positively solvatochromic. By combining Jortner's theory, AM1 computations, and electrooptical absorption measurements (EOAM), this unexpected behavior was shown to be due to a dipole inversion upon S0-->S1 excitation. Furthermore, polarized steady-state fluorescence spectroscopy and EOAM prove that the ground-state geometry of 3 is of lower symmetry than D3 and that the excitation energy can be transferred from one subchromophore to another within the lifetime of the excited state. Exciton-coupling theory was used to quantitatively analyze this excitation transfer.

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Section: Introductionmentioning

confidence: 99%

Electrochemistry and Photophysics of Donor‐Substituted Triarylboranes: Symmetry Breaking in Ground and Excited State

Stahl

Lambert

Kaiser

et al. 2006

Chemistry A European J

161

152

View full text Add to dashboard Cite

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“…Since a decade, boron-based materials have been the focus of numerous researches, especially devoted to Organic Electronics as these materials exhibit a remarkable electron mobility due to the vacant p-orbital of the boron atom [74][75][76]89,90]. Triarylboron derivatives are also characterized by their bulkiness and these materials are also strong electron withdrawing groups.…”

Section: Triarylborane Emittersmentioning

confidence: 99%

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

et al. 2018

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Organic light-emitting diodes offer attractive perspectives for the next generation display and lighting technologies. The potential is huge and the list of potential applications is almost endless. So far, blue emitters still suffer from noticeably inferior electroluminescence performances in terms of efficiency, lifespan, color quality, and charge injection/transport when compared to that of the other colors. Emitting materials matching the NTSC standard blue of coordinates (0.14, 0.08) are extremely rare and still constitutes the focus of numerous academic and industrial researches. In this context, we review herein the recent developments on highly emissive deep-blue thermally activated delayed fluorescence emitters that constitute the third-generation electroluminescent materials.

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“…[29] We observed that the EL emission was dominated by the emission of rubrene ( Figure S3, Supporting Information), confirming the effectiveness of the host-guest energy transfer. We deposited a hole-transport/electron-blocking layer of N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD) [30] from solution for the first time. This simply prepared layer effectively reduces exciton quenching by the MoO x / Au anode.…”

Section: Doi: 101002/adma201605987mentioning

confidence: 99%

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

et al. 2017

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probability of a triplet pair forming a singlet) in solution is >60%, much higher than the spin-statistical prediction of 25% (one pair of triplets collides to form one of the four states: one singlet S 1 and three triplets T 1 , assuming higher triplet and quintet states are inaccessible). Practical application of solar energy conversion requires the TTA-UC material to be in solid state rather than in solution phase. However, the TTA-UC quantum yield of solidstate systems remains low, typically below 5%, [10] and is moderately high (about 10%) in only one example. [19] To achieve high efficiencies, high excitation intensities (200 mW cm −2 or above) are commonly required. These imply that in solid state, the experimentally observed reaction efficiency of TTA-UC was up to about 20%, below the 25% spin-statistical limit.To achieve highly efficient triplet fusion (TTA-UC) in OLEDs and other TTA upconverters, we consider four criteria for the selection of emitters: (1) high fluorescence quantum yield, (2) short singlet lifetime, (3) long triplet lifetime, and (4) the energy of two triplet excitons, 2E(T 1 ) lies slightly above that of the singlet exciton, E(S 1 ), but below the second triplet state, E(T 2 ) (and also the energies of any spin-quintet states) (E(S 1 ) ≲ 2E(T 1 ) < E(T 2 )). The first and second criteria are prerequisites for efficient fluorescence. The third criterion is essential for the accumulation of a sufficiently high triplet population density required for rapid triplet-triplet collision processes. The fourth criterion ensures that higher-lying triplet or quintet states do not provide loss channels. The spin states of the triplet excitons give in principle nine spin configurations for the interacting triplet exciton pair, five associated with a quintet, three with a triplet, and one with the singlet state. It is generally considered that the quintet is always higher in energy than the initial triplet pair, so is neglected. If there are no energetically accessible higher-lying triplet states at E(T 2 ), we expect only the S 1 and T 1 excitons to form. Triplets produced from this reaction can be recycled and participate in a further fusion reaction. [7] The basic working principle of a triplet fusion LED (FuLED) is illustrated in Figure 1a. The initial stage (Stage I) of the device operation includes charge injection and exciton formation. Exciton formation on the emissive molecules may occur directly or indirectly through an additional exciton transfer step from a host material. If a host material is present, the S 1 and T 1 of the host are required to be higher than that of the emitter to allow efficient host-emitter energy transfer and to ensure long triplet lifetime of the emitter (Criterion 3 discussed above). The 25% singlet population can be converted to light emission (and nonradiative losses) from the singlet channel immediately, resulting in prompt electroluminescence (EL). The 75% triplet excitons remain nonemissive, but the population of triplets is When an organic light-emitting dio...

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A Novel Family of Boron‐Containing Hole‐Blocking Amorphous Molecular Materials for Blue‐ and Blue–Violet‐Emitting Organic Electroluminescent Devices

Cited by 102 publications

References 45 publications

Electrochemistry and Photophysics of Donor‐Substituted Triarylboranes: Symmetry Breaking in Ground and Excited State

Electrochemistry and Photophysics of Donor‐Substituted Triarylboranes: Symmetry Breaking in Ground and Excited State

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

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