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

2001 ◽  
Vol 708 ◽  
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.

Electrochemically triggered upconverted luminescence for light-emitting devices

2019 ◽  
Vol 55 (84) ◽  
pp. 12611-12614 ◽  
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.

scholarly journals Investigation of Energy Transfer in Star-Shaped White Polymer Light-Emitting Devices via the Time-Resolved Photoluminescence

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1719 ◽  
Author(s):  
Hui He ◽  
Xiaoqing Liao ◽  
Jiang Cheng ◽  
Ying Li ◽  
Junsheng Yu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Current Efficiency ◽  
Intermolecular Interactions ◽  
Efficient Energy Transfer ◽  
Time Resolved ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Efficient Energy ◽  
Polymer Light Emitting Devices ◽  
Time Resolved Photoluminescence

A series of white polymer light-emitting devices (WPLEDs) were fabricated by utilizing star-shaped white-emission copolymers containing tri[1-phenylisoquinolinato-C2,N]iridium (Ir(piq)3), fluorenone (FO) and poly(9,9-dioctylfluorene) (PFO) as red-, green- and blue-emitting (RGB) components, respectively. In these WPLEDs, a maximum current efficiency of 6.4 cd·A−1 at 20 mA·cm−2 and Commission Internationale d’Eclairage (CIE) coordinates of (0.33, 0.32) were achieved, and the current efficiency was still kept to 4.2 cd·A−1 at the current density of 200 mA·cm−2. To investigate energy transfer processes among the three different chromophores of the star-shaped copolymers in these WPLEDs, the time-resolved photoluminescence (PL) spectra were recorded. By comparing the fluorescence decay lifetimes of PFO chromophores in the four star-like white-emitting copolymers, the efficient energy transfer from PFO units to Ir(piq)3 and FO chromophores was confirmed. From time-resolved PL and the analysis of energy transfer process, the results as follows were proved. Owing to the star-like molecular structure and steric hindrance effect, intermolecular interactions and concentrations quenching in the electroluminescence (EL) process could also be sufficiently suppressed. The efficient energy transfer also reduced intermolecular interactions’ contribution to the enhanced device performances compared to the linear single-polymer white-light systems. Moreover, saturated stable white emission results from the joint of energy transfer and trap-assisted recombination. This improved performance is expected to provide the star-like white-emitting copolymers with promising applications for WPLEDs.

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

Molecules ◽  
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.

New Light Emitting Polymers and High Energy Hosts for Triplet Emission

2004 ◽  
Vol 846 ◽  
Author(s):  
Chris S. K. Mak ◽  
Scott E. Watkins ◽  
Charlotte K. Williams ◽  
Nicholas R. Evans ◽  
Khai Leok Chan ◽  
...  
Keyword(s):  
Green Light ◽  
High Energy ◽  
Design Solution ◽  
Coupling Reactions ◽  
Triplet Energy ◽  
Electron Hole ◽  
Efficient Energy Transfer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Cross Coupling Reactions

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.

Dynamics of Polarons in Guest-Host-System Polymer Light Emitting Devices

1997 ◽  
Vol 488 ◽  
Author(s):  
E.J.W. List ◽  
J. Partee ◽  
W. Graupner ◽  
J. Shinar ◽  
G. Leising
Keyword(s):  
Energy Transfer ◽  
Magnetic Resonance ◽  
Excitation Energy ◽  
Active Layer ◽  
Excitation Energy Transfer ◽  
Light Emitting ◽  
Host System ◽  
Light Emitting Devices ◽  
Polymer Light Emitting Devices

AbstractThe conjugated ladder-type poly(paraphenylene) is an attractive material for blue polymer light emitting devices (PLED). Blending the active layer with small amounts of a red emitting guest polymer, the emission shifts from blue to red with increasing guest concentration due to efficient excitation energy transfer. The results of photoluminescence detected magnetic resonance, electroluminescence detected magnetic resonance measurements and current detected magnetic resonance measurements on PLEDs based on 0.05w%/o - 2w%/o red emitting poly(perylene-co-diethynylbenzene) (PPDB) in the active layer of the PLED are presented and discussed.

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