New Light Emitting Polymers and High Energy Hosts for Triplet Emission

ABSTRACTThis paper describes two aspects of research aimed at harnessing the triplet energy generated in electron-hole recombination in polymer electroluminescent devices. The purpose is to design solution-processible phosphorescent organometallic triplet emitters and to design high triplet energy polymer hosts that can transfer triplet energy to the phosphorescent guests. The method employed Suzuki cross coupling reactions to incorporate either phosphorescent cores or high energy triplet monomers covalently into polymer hosts to evaluate their optoelectronic properties. The results showed (i) efficient energy transfer from polyfluorene hosts to red phosphorescent guests and (ii) that pyridine and carbazole monomers could raise triplet energies of hosts. It is concluded that these approaches offer promise in the design of solution processible electrophosphorescent materials for red and green light emitting devices.

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Singlet and Triplet Energy Transfer in Phosphorescent Dye Doped Polymer Light Emitting Devices

MRS Proceedings ◽

10.1557/proc-708-bb3.40 ◽

2001 ◽

Vol 708 ◽

Cited By ~ 2

Author(s):

Yong-Young Noh ◽

Chang-Lyoul Lee ◽

Hae Won Lee ◽

Hyun-Nam Cho ◽

Jang-Joo Kim

Keyword(s):

Energy Transfer ◽

Conjugated Polymer ◽

Triplet Energy ◽

Efficient Energy Transfer ◽

Light Emitting ◽

Light Emitting Devices ◽

Host Materials ◽

Triplet Energy Transfer ◽

Polymer Light Emitting Devices ◽

Doped Polymer

ABSTRACTEffect of host polymers on energy transfer in phosphorescent dye doped polymer light emitting devices has been investigated. Poly (N-vinylcarbazol) [PVK] and poly (9,9'-di-n-hexyl-2,7-fluorene-alt-1,4(2,5dinhexyloxy) phenylene) [PFHP] were examined as the host materials for the phosphorescent dyes fac tris(2-phenypyridine) irdium(III) [Ir(ppy)3] and 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) [PtOEP]. The host and guest materials have the large spectrum overlap between the emission of the hosts and absorption of the guests. When the guests were doped in PVK, the singlet-singlet and triplet-triplet energy transfer took place efficiently. On the contrary, the energy transfer did not take place from φ-conjugated polymer PFHP to the guests, even though common requirements for Förster and Dexter energy transfer were fulfilled. Host aggregation in PFHP based phosphorescent dye doped light emitting devices can play an undesired role obstructing efficient energy transfer.

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Efficient organic manganese (II) bromide green-light-emitting diodes enabled by manipulating hole and electron transport layer

Journal of Materials Chemistry C ◽

10.1039/d1tc02550c ◽

2021 ◽

Author(s):

Hyunsik Im ◽

Atanu Jana ◽

Vijaya Gopalan Sree ◽

QIANKAI BA ◽

Seong Chan Cho ◽

...

Keyword(s):

Light Emitting Diodes ◽

Green Light ◽

Transport Layer ◽

Lead Free ◽

Electron Transport Layer ◽

Flat Panel Displays ◽

Flat Panel ◽

Inorganic Hybrid ◽

Light Emitting ◽

Light Emitting Devices

Lead-free, non-toxic transition metal-based phosphorescent organic–inorganic hybrid (OIH) compounds are promising for next-generation flat-panel displays and solid-state light-emitting devices. In the present study, we fabricate highly efficient phosphorescent green-light-emitting diodes...

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Pyridinyl-Carbazole Fragments Containing Host Materials for Efficient Green and Blue Phosphorescent OLEDs

Molecules ◽

10.3390/molecules26154615 ◽

2021 ◽

Vol 26 (15) ◽

pp. 4615

Author(s):

Dovydas Blazevicius ◽

Daiva Tavgeniene ◽

Simona Sutkuviene ◽

Ernestas Zaleckas ◽

Ming-Ruei Jiang ◽

...

Keyword(s):

Current Efficiency ◽

Quantum Efficiency ◽

External Quantum Efficiency ◽

Power Efficiency ◽

Triplet Energy ◽

New Host ◽

High Brightness ◽

Light Emitting ◽

Light Emitting Devices ◽

Host Materials

Pyridinyl-carbazole fragments containing low molar mass compounds as host derivatives H1 and H2 were synthesized, investigated, and used for the preparation of electro-phosphorescent organic light-emitting devices (PhOLEDs). The materials demonstrated high stability against thermal decomposition with the decomposition temperatures of 361–386 °C and were suitable for the preparation of thin amorphous and homogeneous layers with very high values of glass transition temperatures of 127–139 °C. It was determined that triplet energy values of the derivatives are, correspondingly, 2.82 eV for the derivative H1 and 2.81 eV for the host H2. The new derivatives were tested as hosts of emitting layers in blue, as well as in green phosphorescent OLEDs. The blue device with 15 wt.% of the iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic) emitter doping ratio in host material H2 exhibited the best overall characteristics with a power efficiency of 24.9 lm/W, a current efficiency of 23.9 cd/A, and high value of 10.3% of external quantum efficiency at 100 cd/m2. The most efficient green PhOLED with 10 wt% of Ir(ppy)3 {tris(2-phenylpyridine)iridium(III)} in the H2 host showed a power efficiency of 34.1 lm/W, current efficiency of 33.9 cd/A, and a high value of 9.4% for external quantum efficiency at a high brightness of 1000 cd/m2, which is required for lighting applications. These characteristics were obtained in non-optimized PhOLEDs under an ordinary laboratory atmosphere and could be improved in the optimization process. The results demonstrate that some of the new host materials are very promising components for the development of efficient phosphorescent devices.

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The dark exciton ground state promotes photon-pair emission in individual perovskite nanocrystals

Nature Communications ◽

10.1038/s41467-020-19740-7 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Philippe Tamarat ◽

Lei Hou ◽

Jean-Baptiste Trebbia ◽

Abhishek Swarnkar ◽

Louis Biadala ◽

...

Keyword(s):

Near Infrared ◽

Exciton State ◽

Lead Iodide ◽

Electron Hole ◽

Light Emitting ◽

Perovskite Nanocrystals ◽

Light Emitting Devices ◽

Optical And Electronic Properties ◽

Wide Range ◽

Halide Perovskites

AbstractCesium lead halide perovskites exhibit outstanding optical and electronic properties for a wide range of applications in optoelectronics and for light-emitting devices. Yet, the physics of the band-edge exciton, whose recombination is at the origin of the photoluminescence, is not elucidated. Here, we unveil the exciton fine structure of individual cesium lead iodide perovskite nanocrystals and demonstrate that it is governed by the electron-hole exchange interaction and nanocrystal shape anisotropy. The lowest-energy exciton state is a long-lived dark singlet state, which promotes the creation of biexcitons at low temperatures and thus correlated photon pairs. These bright quantum emitters in the near-infrared have a photon statistics that can readily be tuned from bunching to antibunching, using magnetic or thermal coupling between dark and bright exciton sublevels.

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Simultaneous realization of high-efficiency, low-drive voltage, and long lifetime TADF OLEDs by multifunctional hole-transporters

Journal of Materials Chemistry C ◽

10.1039/d0tc00330a ◽

2020 ◽

Vol 8 (21) ◽

pp. 7200-7210 ◽

Cited By ~ 2

Author(s):

Takahiro Kamata ◽

Hisahiro Sasabe ◽

Nozomi Ito ◽

Yoshihito Sukegawa ◽

Ayato Arai ◽

...

Keyword(s):

High Efficiency ◽

Triplet Energy ◽

Energy Hole ◽

Light Emitting ◽

Drive Voltage ◽

Light Emitting Devices ◽

Thermally Activated ◽

Highly Efficient ◽

Organic Light ◽

Long Lifetime

A smart high-triplet energy hole-transporter exhibits significant stability in the anion state realizing record-breaking highly efficient and long-living thermally activated delayed fluorescent (TADF) organic light-emitting devices (OLEDs).

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Electrochemically triggered upconverted luminescence for light-emitting devices

Chemical Communications ◽

10.1039/c9cc05845a ◽

2019 ◽

Vol 55 (84) ◽

pp. 12611-12614 ◽

Cited By ~ 3

Author(s):

Haruki Minami ◽

Takuya Ichikawa ◽

Kazuki Nakamura ◽

Norihisa Kobayashi

Keyword(s):

Energy Transfer ◽

Triplet Energy ◽

Light Emitting ◽

Light Emitting Devices ◽

Triplet Energy Transfer ◽

First Time ◽

Triplet Triplet Annihilation

Electrochemically triggered upconverted luminescence through triplet–triplet energy transfer (TTET) and subsequent triplet–triplet annihilation upconversion (TTA-UC) is observed for the first time.

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Ultrapure and highly efficient green light emitting devices based on ligand-modified CsPbBr3 quantum dots

Photonics Research ◽

10.1364/prj.391703 ◽

2020 ◽

Vol 8 (7) ◽

pp. 1086 ◽

Cited By ~ 11

Author(s):

Dongdong Yan ◽

Shuangyi Zhao ◽

Huaxin Wang ◽

Zhigang Zang

Keyword(s):

Quantum Dots ◽

Green Light ◽

Light Emitting ◽

Light Emitting Devices ◽

Highly Efficient ◽

Cspbbr3 Quantum Dots

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Structures and photophysical properties of two luminescent bipyridine compounds: 2′,6′-difluoro-6-[3-(pyridin-2-yloxy)phenyl]-2,3′-bipyridine and 2′,6′-dimethoxy-6-[3-(pyridin-2-yloxy)phenyl]-2,3′-bipyridine

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229620004301 ◽

2020 ◽

Vol 76 (5) ◽

pp. 381-388

Author(s):

Ki-Min Park ◽

Kiyull Yang ◽

Suk-Hee Moon ◽

Youngjin Kang

Keyword(s):

Theoretical Calculations ◽

Photophysical Properties ◽

Three Dimensional ◽

Organic Light Emitting Diodes ◽

Coupling Reactions ◽

X Ray Diffraction ◽

Light Emitting ◽

Cross Coupling Reactions ◽

Host Materials ◽

Supramolecular Networks

The title compounds, C21H13F2N3O (1) and C23H19N3O3 (2), have been synthesized by typical cross-coupling reactions. Both compounds have been characterized by single-crystal X-ray diffraction. Bipyridine 1 exhibits a fully extended structure in which the terminal pyridine rings are oriented away from each other, while bipyridine 2 displays a bent structure in which terminal pyridine rings are oriented in the same direction. Several intermolecular interactions lead to the formation of two- and three-dimensional supramolecular networks in the crystal structures of 1 and 2, respectively. Compound 1 bears fluorine substituents and emits a strong fluorescence with λmax = 325 nm, while methoxy-substituted compound 2 displays red-shifted emissions with λmax = 366 nm. The emissions observed in both compounds originate from phenyl- and 2,3′-bipyridine-based π–π* transitions, according to theoretical calculations. Both compounds have high triplet energies (T1) ranging from 2.64 to 2.65 eV, which makes them potential host materials in organic light-emitting diodes (OLEDs).

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