Efficient white polymer light-emitting electrochemical cells

Xiong, Yan; Li, Lü; Liang, Jiajie; Gao, Huier; Chou, Shu-Yu; Pei, Qibing

doi:10.1039/c4mh00204k

Cited by 54 publications

(37 citation statements)

References 25 publications

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“…This feature increases their potential for use in traditional LEDs and even in soft-based light-emitting devices, such as light-emitting electrochemical cells (LECs). LECs are low-cost, easy fabrication lightening devices [16,36,37,38] based on a luminescent polymer mixed with mobile ionic species or intrinsically ionic transition-metal complexes. The introduction of the flexible chain ending with an ionic group [39,40,41] in the ligands made the metallated polymers compatible with an ionic medium.…”

Section: Introductionmentioning

confidence: 99%

A Highly Efficient White Luminescent Zinc (II) Based Metallopolymer by RGB Approach

2019

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Three aryl-hydrazone O,N,O tridentate ligands with a different electron-withdrawing substituent were prepared. The introduction of a flexible charged chain in the ligands guaranteed solubility in many organic solvents and in water. The increasing withdrawing aptitude of the substituents red-shifted the emission in the correspondent metallopolymers. The metallated polymers were obtained by grafting ligand-zinc (II) coordination fragments onto commercial poly-(4-vinylpyridine). Metallopolymers thin films exhibited red, green and blue emission colors defined by Commission Internationale d’Eclairage (CIE) coordinates and medium to excellent photoluminescence (PL) quantum yields (PLQYs) comparable with other highly-performing active materials for Light-Emitting Diodes (LEDs). By grafting a suitable mix of the three different coordination pendants, an efficient single-component white emissive metallopolymer with CIE (0.30, 0.31) was prepared. Thanks to the charged moiety, the polymers resulted miscible with an ionic liquid. The addition produced homogeneous polymeric layers with unaltered PL performances, potentially employable in Light-emitting Electrochemical Cells (LECs).

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Section: Introductionmentioning

confidence: 99%

A Highly Efficient White Luminescent Zinc (II) Based Metallopolymer by RGB Approach

2019

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“…LECs have recently gained some record high efficiencies (99 cd A −1 ) even when operated at high luminance levels (>1900 cd m −2 ) . Solution‐processed LECs now offer various colors and very high luminance . These achievements bring LECs closer to commercial relevance.…”

Section: Introductionmentioning

confidence: 99%

Stress Testing Polymer Light‐Emitting Electrochemical Cells: Suppression of Voltage Drift and Black Spot Formation

Gao

2018

Adv Materials Technologies

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The stress characteristics of the polymer light‐emitting electrochemical cells (PLECs) are comprehensively evaluated by varying a host of material and operational parameters. PLECs with the lowest salt concentration of less than 2.5% exhibit runaway voltage drift that leads to rapid cell destruction. PLECs with the lowest electrolyte polymer concentration and a 5% salt content exhibit the longest luminance half‐life, but are slow to activate and are plagued by black spots. At moderate‐to‐high electrolyte concentrations, the PLECs are relatively stable but are not immune to black spots and voltage drift. A lifetime figure‐of‐merit is introduced to quantitatively account for all three indicators of cell degradation in luminance decay, voltage drift, and black spot formation. A surprising discovery is that voltage drift and black spot formation can be effectively suppressed by drastically increasing the electrolyte content. A cell with a 70% electrolyte content exhibits the best lifetime of nearly 350 h when operated at a constant current density of 167 mA cm−2. The black spots can also be effectively eliminated by employing silver instead of aluminum as the cathode material.

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“…Injection of charges into the semiconducting polymer, and the charge compensation provided by the ions, form p-and n-doped regions at the anode and cathode sides, respectively 3,4,5,6 . Compared to conventional OLEDs, LECs are single-layer devices with low turn-on voltage and insensitivity to the film thickness and the work function of the electrode materials 7,8,9,10 .…”

Section: Introductionmentioning

confidence: 99%

Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells

Jafari

Liu

Engquist

et al. 2017

ACS Appl. Mater. Interfaces

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An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p-n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p-n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.

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Efficient white polymer light-emitting electrochemical cells

Abstract: An efficient white polymer light-emitting electrochemical cell has been fabricated with a thin-film sandwich architecture of glass/indium tin oxide/electroluminescent layer/aluminum.

Cited by 54 publications

References 25 publications

A Highly Efficient White Luminescent Zinc (II) Based Metallopolymer by RGB Approach

A Highly Efficient White Luminescent Zinc (II) Based Metallopolymer by RGB Approach

Stress Testing Polymer Light‐Emitting Electrochemical Cells: Suppression of Voltage Drift and Black Spot Formation

Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells

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