Organic Optoelectronic Devices Containing Water/Alcohol‐Soluble Conjugated Polymers and Conjugated Polyelectrolytes*

Hu, Sujun; Zhong, Chengmei; Wu, Hongbin; Cao, Yong

doi:10.1002/9783527655700.ch11

Cited by 5 publications

(3 citation statements)

References 192 publications

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“…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) . These may be anionic (e.g., polysulfonates with alkali or alkylammonium cations as counterions), cationic (mainly alkylammonium or N-heterocyclic cations, like, e.g., imidazolium with corresponding halide anions), or even zwitterionic (e.g., ammonium sulfonates without free counterions) or diblock or triblock copolymers. Recently, the importance of the conjugated nature of the polyelectrolytes used as electron injecting layers was put into question. − In fact, Min et al reported on a small molecule zwitterionic compound without any π-delocalized unit, which showed excellent device performance…”

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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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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“…Conjugated polyelectrolytes (CPEs) are macromolecules that contain an electronically delocalized backbone and solubilizing side groups with ionizable functionalities . CPEs are therefore soluble in polar solvents and combine the dependence of polyelectrolytes on electrostatic forces with the properties of organic semiconductors. As a result of these unique properties, CPEs have been extensively applied in biosensors , and single-component light-emitting electrochemical cells (LECs) and as interfacial layers in multilayer polymer light-emitting diodes (PLEDs), − organic photovoltaics, , and field-effect transistors .…”

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confidence: 99%

Operational Mechanism of Conjugated Polyelectrolytes

et al. 2014

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Conjugated polyelectrolytes (CPEs) are versatile materials used in a range of organic optoelectronic applications. Because of their ionic/electronic nature, characterizing these materials is nontrivial, and their operational mechanism is not fully understood. In this work we use a methodology that combines constant-voltage-driven current-density transient measurements with fast current vs voltage scans to allow decoupling of ionic and electronic phenomena. This technique is applied to diodes prepared with cationic CPEs having different charge-compensating anions. Our results indicate that the operational mechanism of these devices is governed by electrochemical doping of the CPE. On the basis of the notion that the saturated depletion layer for the anions consists of the same π-conjugated backbone material, we discern how the extent and speed of formation of the doped region depend on the anion structure. Apart from addressing fundamental transport questions, this work provides a tool for future characterization of different CPEs and other similar systems.

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“…While the exact ratio would be dependent on the specific system, solid hole-conductors seem to disfavour carrier recombination more than a liquid electrolyte system. Early research to replace the liquid electrolyte explored replacing it with conductive, organic polymers [46][47][48][49]; more recently the use of inorganic semiconductors as possible alternatives has emerged [50][51][52][53][54][55][56][57].…”

Section: Introductionmentioning

confidence: 99%