Observation of up-conversion fluorescence from exciplex of m-MTDATA:TPBi blend

Du, Hongchuan; Zhou, Qian; Yu, Yuan; Liu, Chenghao; Zhang, Xijian; Pang, Zhiyong; Han, Shiguo

doi:10.1016/j.jlumin.2021.118655

Cited by 8 publications

(8 citation statements)

References 34 publications

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“…This conception generates an ensemble of p ⃗ CT directed orthogonal to the interface plane, as recently evidenced for a material system comparable to ours . In this study, we use thin evaporated films of m-MTDATA and TPBi, as their interface was reported to form an efficient emissive CT state. , These films are sandwiched between aluminum and indium tin oxide (ITO) electrodes.…”

Section: Conceptionsupporting

confidence: 59%

“…The measured values of the EL peak are similar to the expected E CT around 2 eV, corresponding to the HOMO−LUMO offset of the bulk materials reduced by their Coulomb interaction. No significant m-MTDATA bulk emission around 420 nm (2.9 eV) 31,32 is observed. Increasing the intrinsic layer thickness from 0 to 20 nm increases (decreases) the peak-emission energy (wavelength) by over 200 meV (60 nm), approaching the emission wavelengths reported for the undoped systems, that is 520 nm for the bulk and 550 nm for the planar heterojunction.…”

Section: ■ Resultsmentioning

confidence: 94%

“… 29 In this study, we use thin evaporated films of m-MTDATA and TPBi, as their interface was reported to form an efficient emissive CT state. 31 , 32 These films are sandwiched between aluminum and indium tin oxide (ITO) electrodes.…”

Section: Conceptionmentioning

confidence: 99%

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Tuning Charge-Transfer States by Interface Electric Fields

Kirch,

Wolansky,

Miri Aabi Soflaa

et al. 2024

ACS Appl. Mater. Interfaces

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Intermolecular charge-transfer (CT) states are extended excitons with a charge separation on the nanometer scale. Through absorption and emission processes, they couple to the ground state. This property is employed both in light-emitting and light-absorbing devices. Their conception often relies on donor−acceptor (D−A) interfaces, so-called type-II heterojunctions, which usually generate significant electric fields. Several recent studies claim that these fields alter the energetic configuration of the CT states at the interface, an idea holding prospects like multicolor emission from a single emissive interface or shifting the absorption characteristics of a photodetector. Here, we test this hypothesis and contribute to the discussion by presenting a new model system. Through the fabrication of planar organic p-(i-)n junctions, we generate an ensemble of oriented CT states that allows the systematic assessment of electric field impacts. By increasing the thickness of the intrinsic layer at the D−A interface from 0 to 20 nm and by applying external voltages up to 6 V, we realize two different scenarios that controllably tune the intrinsic and extrinsic electric interface fields. By this, we obtain significant shifts of the CT-state peak emission of about 0.5 eV (170 nm from red to green color) from the same D−A material combination. This effect can be explained in a classical electrostatic picture, as the interface electric field alters the potential energy of the electric CT-state dipole. This study illustrates that CT-state energies can be tuned significantly if their electric dipoles are aligned to the interface electric field.

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Section: Conceptionsupporting

confidence: 59%

Section: ■ Resultsmentioning

confidence: 94%

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Tuning Charge-Transfer States by Interface Electric Fields

Kirch,

Wolansky,

Miri Aabi Soflaa

et al. 2024

ACS Appl. Mater. Interfaces

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“…In previous work, we developed a strategy to design NLO exciplexes and observed strong TPEF in several exciplex-based TADF materials. − The observed upconversion fluorescence is significantly strong benefiting from the RISC processes enabled by the small Δ E ST . Although the exciplexes successfully demonstrate their abilities of suppressing the triplet–triplet annihilation by converting triplets to singlets, the full exciton utilization is far from being realized in conventional binary exciplex materials and devices. − This can be confirmed by their photoluminescence quantum yields (PLQYs) and external quantum efficiencies (EQEs), which are much lower than the theoretical limits. , For both linear and nonlinear optical applications, developing strategies to further improve the utilization of nonradiative states is highly desired.…”

Section: Introductionmentioning

confidence: 99%

Ternary Exciplexes for Enhanced Two-Photon Excited Fluorescence by the Synergy Effect of Dual Reverse Intersystem Crossing Channels

Zhou

et al. 2023

J. Phys. Chem. C

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A nonlinear optical (NLO) ternary exciplex is developed using a two-photon absorbing acceptor material tris- (2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB), a twophoton absorbing donor material 4,4′-cyclohexylidenebis[N,N-bis(ptolyl)aniline] (TAPC), and a linear optical acceptor material 2,4,6tris(1,1′-biphenyl)-1,3,5-triazine (T2T). In the ternary mixture, the high-energy exciplex TAPC:3TPYMB and the low-energy exciplex TAPC:T2T generate an effective synergy effect on the basis of their reverse intersystem crossing (RISC) channels to achieve further utilization of triplet excitons, giving rise to significantly enhanced one-and two-photon excited fluorescence properties. The highest photoluminescence quantum yield (PLQY) of the ternary exciplex 3TPYMB:TAPC:T2T measured in air atmosphere is ∼77.8%, which is greatly improved compared to that of the binary exciplex TAPC:T2T (∼39.6%) and the binary exciplex TAPC:3TPYMB (∼3.7%). More interestingly, the ternary exciplex also exhibits enhanced two-photon excited fluorescence under long-wavelength laser excitation. In comparison, no improvement in PLQY is observed in another ternary exciplex 3TPYMB:4,4′,4″-tris(carbazole-9yl)triphenylamine (TCTA):T2T, which lacks an effective synergy effect between its high-and low-energy exciplex RISC channels. Our synergistic dual-channel RISC strategy may be helpful for the design of multicomponent thermally activated delayed fluorescence (TADF) NLO materials and facilitate the development of NLO applications.

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“…Organic chromophores have attracted much research attention in recent years due to their promising applications in the field of light-emitting devices, lasers, nonlinear optics, sensors, and solar cells. − Motivated by the increasing demands for energy-saving and high-performance commercial optoelectronic products, great efforts have been made in the design and preparation of highly efficient molecular light-emitting materials. − Although organic molecules often have the advantages of being easy to be tailored and modified, , the pursuit of high-performance organic light-emitting materials is a long-term research task in view of the energy loss mechanism in organic chromophores.…”

Section: Introductionmentioning

confidence: 99%

High-PLQY and Efficient Upconverted Fluorescence of the TAPC/PBD Exciplex with Fluorescent Guests

Zhou

et al. 2022

J. Phys. Chem. C

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The pursuit of high-performance low-cost organic light-emitting materials is a long-term task. The down-and upconverted fluorescence from an electron donor−acceptor host composed of di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole with fluorescent guests, 9,10-bis[N,N-di-(p-tolyl)-amino]anthracene (TTPA) and 5,6,11,12-tetraphenylnaphthacene (rubrene), was investigated. We found that the energy loss mechanism can be greatly suppressed by the effective Forster resonance energytransfer process from the exciplex host to fluorescent guests. An extremely high photoluminescence quantum yield (PLQY) up to 98.41% was achieved, as well as strong upconverted green, orange, and blue fluorescence was observed in TTPA-, rubrene-, and undoped exciplex blends, respectively, under the excitation of near-infrared femtosecond laser. These low-cost materials with high PLQYs and strong upconverted fluorescence properties may have great application potential in light-emitting devices, lasers, and bioimaging applications.

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Observation of up-conversion fluorescence from exciplex of m-MTDATA:TPBi blend

Cited by 8 publications

References 34 publications

Tuning Charge-Transfer States by Interface Electric Fields

Tuning Charge-Transfer States by Interface Electric Fields

Ternary Exciplexes for Enhanced Two-Photon Excited Fluorescence by the Synergy Effect of Dual Reverse Intersystem Crossing Channels

High-PLQY and Efficient Upconverted Fluorescence of the TAPC/PBD Exciplex with Fluorescent Guests

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