Efficient Green Electrophosphorescence with Al Cathode Using an Effective Electron-Injecting Polymer As the Host

Chen, Zhao; Niu, Qiao; Zhang, Yong; Ying, Lei; Peng, Junbiao; Cao, Yong

doi:10.1021/am9005258

Cited by 7 publications

(4 citation statements)

References 21 publications

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“…Recently, it was recognized that despite the presence of the low‐lying triplet states, conjugated polyfluorenes and their derivatives can be utilized as the host for green phosphorescent complex fac ‐tris(2‐(4‐ tert ‐butyl)‐phenylpyridine)iridium (Ir( t ‐Bu‐PPy) 3 ), as long as there is a thin layer of PVK incorporated as the anode buffer layer . The reduced phosphorescent quenching was also found to be associated with the exciton formation and charge carrier recombination within the PVK layer and the PVK/poly(9,9‐dioctylfluorene) (PFO) interface due to the accumulation of holes .…”

Section: Device Engineering For Wpledsmentioning

confidence: 99%

White Polymer Light‐Emitting Devices for Solid‐State Lighting: Materials, Devices, and Recent Progress

et al. 2014

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White polymer light-emitting devices (WPLEDs) have become a field of immense interest in both scientific and industrial communities. They have unique advantages such as low cost, light weight, ease of device fabrication, and large area manufacturing. Applications of WPLEDs for solid-state lighting are of special interest because about 20% of the generated electricity on the earth is consumed by lighting. To date, incandescent light bulbs (with a typical power efficiency of 12-17 lm W(-1) ) and fluorescent lamps (about 40-70 lm W(-1) ) are the most widely used lighting sources. However, incandescent light bulbs convert 90% of their consumed power into heat while fluorescent lamps contain a small but significant amount of toxic mercury in the tube, which complicates an environmentally friendly disposal. Remarkably, the device performances of WPLEDs have recently been demonstrated to be as efficient as those of fluorescent lamps. Here, we summarize the recent advances in WPLEDs with special attention paid to the design of novel luminescent dopants and device structures. Such advancements minimize the gap (for both efficiency and stability) from other lighting sources such as fluorescent lamps, light-emitting diodes based on inorganic semiconductors, and vacuum-deposited small-molecular devices, thus rendering WPLEDs equally competitive as these counterparts currently in use for illumination purposes.

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Section: Device Engineering For Wpledsmentioning

confidence: 99%

White Polymer Light‐Emitting Devices for Solid‐State Lighting: Materials, Devices, and Recent Progress

et al. 2014

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“…On the other hand, ion conducting polymers such as poly(ethyleneoxide) (PEO), PEGDE or PEGDE/rubrene, or even blends of an alkaline salt (e.g., Cs 2 CO 3 or KCF 3 SO 3 ) or an anionic surfactant (e.g., sodium dodecyl sulfate) with PEO have been suggested as solution processable interfacial layers. An alternative pathway involves the use of all-organic solution-deposited materials, such as properly functionalized conjugated polymers, , while Zhou et al have proposed implementing amine-bearing large band gap polymeric surface modifiers that lower substantially the work function of several materials used as cathode electrodes in different optoelectronic devices . In this direction, the most popular approach so far is based on the use of conjugated polymers with pendant ionic groups, the so-called conjugated polyelectrolytes (CPEs) .…”

Section: Introductionmentioning

confidence: 99%

All-Organic Sulfonium Salts Acting as Efficient Solution Processed Electron Injection Layer for PLEDs

Georgiadou

Vasilopoulou

Palilis

et al. 2013

ACS Appl. Mater. Interfaces

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Herein we introduce the all-organic triphenylsulfonium (TPS) salts cathode interfacial layers (CILs), deposited from their methanolic solution, as a new simple strategy for circumventing the use of unstable low work function metals and obtaining charge balance and high electroluminescence efficiency in polymer light-emitting diodes (PLEDs). In particular, we show that the incorporation of TPS-triflate or TPS-nonaflate at the polymer/Al interface improved substantially the luminous efficiency of the device (from 2.4 to 7.9 cd/A) and reduced the turn-on and operating voltage, whereas an up to 4-fold increase in brightness (∼11 250 cd/m(2) for TPS-triflate and ∼14 682 cd/m(2) for TPS-nonaflate compared to ∼3221 cd/m(2) for the reference device) was observed in poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-2,1',3-thiadiazole)] (F8BT)-based PLEDs. This was mainly attributed to the favorable decrease of the electron injection barrier, as derived from the open-circuit voltage (Voc) measurements, which was also assisted by the conduction of electrons through the triphenylsulfonium salt sites. Density functional theory calculations indicated that the total energy of the anionic (reduced) form of the salt, that is, upon placing an electron to its lowest unoccupied molecular orbital, is lower than its neutral state, rendering the TPS-salts stable upon electron transfer in the solid state. Finally, the morphology optimization of the TPS-salt interlayer through controlling the processing parameters was found to be critical for achieving efficient electron injection and transport at the respective interfaces.

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“…The utilization of conjugated polyelectrolyte or its precursor as an interlayer between the active layer and the high E Φ metal cathode have been widely investigated in recent decades for PLEDs − and polymer solar cells (PSCs) − for promoting device performance. They are composed of conjugated polymer main chain and pendant high-polarity moieties such as sulfate-, − phosphonate-, − diethanolamino-, − dimethylamino-, − dimethylammonium-, − or crown ether − as the side chain. As for PLEDs, the introduction of conjugated polyelectrolyte or its precursor as an electron-injection layer (EIL) has been confirmed to form an interfacial dipole ,− ,, to environmentally stable high E Φ metal cathode such as Al and Ag.…”

Section: Introductionmentioning

confidence: 99%

Electric-Field-Induced Excimer Formation at the Interface of Deep-Blue Emission Poly(9,9-dioctyl-2,7-fluorene) with Polyelectrolyte or Its Precursor as Electron-Injection Layer in Polymer Light-Emitting Diode and Its Prevention for Stable Emission and Higher Performance

Tsai

Jen

et al. 2018

ACS Appl. Mater. Interfaces

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Conjugated polyelectrolytes and their precursors as electron-injection layer (EIL) in polymer light-emitting diode have attracted extensive attention because they allow the use of environmentally stable high work function metals as cathode with efficient electron injection. Here, for the first time, we find that an undesirable green emission component (470-650 nm) in the electroluminescence spectra is observed during continuous operation of deep-blue emission β-phase poly(9,9-dioctyl-2,7-fluorene) (β-PFO) device upon introducing polyelectrolyte poly[9,9-bis(6'-(18-crown-6)methoxy)hexyl fluorene] chelating to potassium ion (PFCn6:K) as EIL. This phenomenon also happens to nonchelating PFCn6, poly[(9,9-bis(3'-( N, N-dimethylamino)propyl)-2,7-fluorene)- alt-2,7-(9,9-dioctylfluorene)], or even nonemissive poly[4-((18-crown-6)methoxy)methyl styrene] chelating to K (PSCn6:K). It can be ascribed to electric-field induction accompanied by thermal motion of a highly polar side chain in the polyelectrolyte leading to local segmental alignment of PFO main chains at the emitting layer (EML)/EIL interface and thus formation of green emission excimer, which is supported by the following observations: appearance of green emission component using nonemissive PSCn6:K as EIL, absence of green emission component as the device is operated at low-temperature (78 K) at which molecular thermal motion are frozen, and absence of green emission upon introducing 2,2',2″-(1,3,5-phenylbenzenetriyl)tris[1-phenyl-1 H-benzimidazole] as buffer layer in between EML and EIL for the prevention of direct contact of EML with polyelectrolyte or its precursor EIL.

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Efficient Green Electrophosphorescence with Al Cathode Using an Effective Electron-Injecting Polymer As the Host

Cited by 7 publications

References 21 publications

White Polymer Light‐Emitting Devices for Solid‐State Lighting: Materials, Devices, and Recent Progress

White Polymer Light‐Emitting Devices for Solid‐State Lighting: Materials, Devices, and Recent Progress

All-Organic Sulfonium Salts Acting as Efficient Solution Processed Electron Injection Layer for PLEDs

Electric-Field-Induced Excimer Formation at the Interface of Deep-Blue Emission Poly(9,9-dioctyl-2,7-fluorene) with Polyelectrolyte or Its Precursor as Electron-Injection Layer in Polymer Light-Emitting Diode and Its Prevention for Stable Emission and Higher Performance

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