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

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1712 ◽  
Author(s):  
Barbara Panunzi ◽  
Rosita Diana ◽  
Ugo Caruso
Keyword(s):  
Thin Films ◽  
Ionic Liquid ◽  
Organic Solvents ◽  
Light Emitting Diodes ◽  
Blue Emission ◽  
Quantum Yields ◽  
Electrochemical Cells ◽  
Active Materials ◽  
Tridentate Ligands ◽  
Light Emitting

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).

An ester-substituted polyfluorene derivative for light-emitting electrochemical cells: bright blue emission and its application in a host–guest system

2018 ◽  
Vol 2 (5) ◽  
pp. 952-958 ◽  
Author(s):  
Go Nagatsu ◽  
Tomo Sakanoue ◽  
Shizuka Tane ◽  
Fumihiro Yonekawa ◽  
Taishi Takenobu
Keyword(s):  
Ionic Liquid ◽  
Blue Emission ◽  
Bright Light ◽  
Electrochemical Cells ◽  
Light Emitting ◽  
System P ◽  
Guest System ◽  
Bright Blue

Ester substitution realized phase compatible film blends of a polymer and an ionic liquid for bright light-emitting electrochemical cells.

scholarly journals Stable blue-emissive aluminum acetylacetonate nanocrystals with high quantum yield of over 80% and embedded in polymer matrix for remote UV-pumped white light–emitting diodes

Nanophotonics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1509-1518
Author(s):  
Hong Zheng ◽  
Bingkun Chen ◽  
Lifu Shi ◽  
Fa Zhang ◽  
Ziheng Zhao ◽  
...  
Keyword(s):  
Composite Film ◽  
White Light ◽  
Light Emitting Diodes ◽  
Composite Films ◽  
Blue Emission ◽  
Quantum Yields ◽  
Aluminum Compound ◽  
Light Emitting ◽  
Air Atmosphere ◽  
White Light Emitting Diodes

AbstractBlue-emissive nanocrystals (NCs) with high photoluminescence quantum yields (PL QYs) and excellent stability are essential for lighting and displays. Here, a facile top-down approach (including two steps: thermal annealing and ultrasonic treatment) by using aluminum acetylacetonate (Al(acac)3) as a precursor is adopted to fabricate blue-emissive Al(acac)3 NCs with high PL QY reaching 81.8%, the highest reported value for the aluminum compound-based NCs so far. Additionally, the as-fabricated Al(acac)3 NC solution (in toluene) exhibits high stability under air atmosphere condition, maintaining 61.2% of initial PL QY after 1 year. Furthermore, solution-processed Al(acac)3 NCs/poly(methyl methacrylate) (PMMA) composite film with blue emission is demonstrated. Finally, combinations of the blue-emitting Al(acac)3 NCs/PMMA composite film with red-emitting and green-emitting CuInS2 composite films are realized, resulting in remote ultraviolet-pumped white light-emitting diodes with a high color rendering index of 91. These findings inform new blue-emissive NCs and composite films, potentially paving the way to design new structures of lighting and display devices.

scholarly journals High-performance quasi-2D perovskite light-emitting diodes: from materials to devices

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Li Zhang ◽  
Changjiu Sun ◽  
Tingwei He ◽  
Yuanzhi Jiang ◽  
Junli Wei ◽  
...  
Keyword(s):  
Energy Transfer ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Structural Characteristics ◽  
Quantum Yields ◽  
Research Directions ◽  
Light Emitting ◽  
Perovskite Materials ◽  
Quantum Confinement Effects ◽  
Semiconducting Properties

AbstractQuasi-two-dimensional (quasi-2D) perovskites have attracted extraordinary attention due to their superior semiconducting properties and have emerged as one of the most promising materials for next-generation light-emitting diodes (LEDs). The outstanding optical properties originate from their structural characteristics. In particular, the inherent quantum-well structure endows them with a large exciton binding energy due to the strong dielectric- and quantum-confinement effects; the corresponding energy transfer among different n-value species thus results in high photoluminescence quantum yields (PLQYs), particularly at low excitation intensities. The review herein presents an overview of the inherent properties of quasi-2D perovskite materials, the corresponding energy transfer and spectral tunability methodologies for thin films, as well as their application in high-performance LEDs. We then summarize the challenges and potential research directions towards developing high-performance and stable quasi-2D PeLEDs. The review thus provides a systematic and timely summary for the community to deepen the understanding of quasi-2D perovskite materials and resulting LED devices.

scholarly journals Solution-Processed Efficient Blue Phosphorescent Organic Light-Emitting Diodes (PHOLEDs) Enabled by Hole-Transport Material Incorporated Single Emission Layer

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 554
Author(s):  
Taeshik Earmme
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Emission Layer ◽  
Solution Processed ◽  
Light Emitting ◽  
Organic Light ◽  
Single Emission ◽  
Blue Phosphorescent

Solution-processed blue phosphorescent organic light-emitting diodes (PHOLEDs) based on a single emission layer with small-molecule hole-transport materials (HTMs) are demonstrated. Various HTMs have been readily incorporated by solution-processing to enhance hole-transport properties of the polymer-based emission layer. Poly(N-vinylcarbazole) (PVK)-based blue emission layer with iridium(III) bis(4,6-(di-fluorophenyl)pyridinato-N,C2′)picolinate (FIrpic) triplet emitter blended with solution-processed 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) gave luminous efficiency of 21.1 cd/A at a brightness of 6220 cd/m2 with an external quantum efficiency (EQE) of 10.6%. Blue PHOLEDs with solution-incorporated HTMs turned out to be 50% more efficient compared to the reference device without HTMs. The high hole mobility, high triplet energy of HTM, and favorable energy transfer between HTM blended PVK host and FIrpic blue dopant were found to be important factors for achieving high device performance. The results are instructive to design and/or select proper hole-transport materials in solution-processed single emission layer.

scholarly journals Dimension control of in situ fabricated CsPbClBr2 nanocrystal films toward efficient blue light-emitting diodes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Chenhui Wang ◽  
Dengbao Han ◽  
Junhui Wang ◽  
Yingguo Yang ◽  
Xinyue Liu ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Blue Emission ◽  
Light Emitting ◽  
Mixed Ligands ◽  
Dimension Control ◽  
Nanocrystal Films ◽  
Width Distribution ◽  
Quantum Well Width

AbstractIn the field of perovskite light-emitting diodes (PeLEDs), the performance of blue emissive electroluminescence devices lags behind the other counterparts due to the lack of fabrication methodology. Herein, we demonstrate the in situ fabrication of CsPbClBr2 nanocrystal films by using mixed ligands of 2-phenylethanamine bromide (PEABr) and 3,3-diphenylpropylamine bromide (DPPABr). PEABr dominates the formation of quasi-two-dimensional perovskites with small-n domains, while DPPABr induces the formation of large-n domains. Strong blue emission at 470 nm with a photoluminescence quantum yield up to 60% was obtained by mixing the two ligands due to the formation of a narrower quantum-well width distribution. Based on such films, efficient blue PeLEDs with a maximum external quantum efficiency of 8.8% were achieved at 473 nm. Furthermore, we illustrate that the use of dual-ligand with respective tendency of forming small-n and large-n domains is a versatile strategy to achieve narrow quantum-well width distribution for photoluminescence enhancement.

scholarly journals Two-dimensional perovskites with alternating cations in the interlayer space for stable light-emitting diodes

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yiyue Zhang ◽  
Masoumeh Keshavarz ◽  
Elke Debroye ◽  
Eduard Fron ◽  
Miriam Candelaria Rodríguez González ◽  
...  
Keyword(s):  
Thin Films ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Interlayer Space ◽  
High Current Density ◽  
Operational Stability ◽  
Infrared Light ◽  
Two Dimensional ◽  
Commercial Development ◽  
Light Emitting

Abstract Lead halide perovskites have attracted tremendous attention in photovoltaics due to their impressive optoelectronic properties. However, the poor stability of perovskite-based devices remains a bottleneck for further commercial development. Two-dimensional perovskites have great potential in optoelectronic devices, as they are much more stable than their three-dimensional counterparts and rapidly catching up in performance. Herein, we demonstrate high-quality two-dimensional novel perovskite thin films with alternating cations in the interlayer space. This innovative perovskite provides highly stable semiconductor thin films for efficient near-infrared light-emitting diodes (LEDs). Highly efficient LEDs with tunable emission wavelengths from 680 to 770 nm along with excellent operational stability are demonstrated by varying the thickness of the interlayer spacer cation. Furthermore, the best-performing device exhibits an external quantum efficiency of 3.4% at a high current density (J) of 249 mA/cm2 and remains above 2.5% for a J up to 720 mA cm−2, leading to a high radiance of 77.5 W/Sr m2 when driven at 6 V. The same device also shows impressive operational stability, retaining almost 80% of its initial performance after operating at 20 mA/cm2 for 350 min. This work provides fundamental evidence that this novel alternating interlayer cation 2D perovskite can be a promising and stable photonic emitter.

Four color stacked white organic light-emitting diodes utilizing the concept of triplet harvesting

2011 ◽  
Vol 1286 ◽  
Author(s):  
Th. C. Rosenow ◽  
S. Olthof ◽  
S. Reineke ◽  
B. Lüssem ◽  
K. Leo
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Organic Light Emitting Diodes ◽  
Light Sources ◽  
Emission Layer ◽  
Light Emitting ◽  
Organic Light ◽  
Blue Emitters ◽  
Color Rendering ◽  
Triplet Harvesting

ABSTRACTOrganic light-emitting diodes (OLEDs) are developing into a competitive alternative to conventional light sources. Nevertheless, OLEDs need further improvement in terms of efficiency and color rendering for lighting applications. Fluorescent blue emitters allow deep blue emission and high stability, while phosphorescent blue emitter still suffer from insufficient stability. The concept of triplet harvesting is the key for achieving internal quantum efficiencies up to 100 % and simultaneously benefiting from the advantages of fluorescent blue emitters. Here, we present a stacked OLED consisting of two units comprising four different emitters in total. The first unit takes advantage of the concept of triplet harvesting and combines the light emission of a fluorescent blue and a phosphorescent red emitter. The second unit emits light from a single emission layer consisting of a matrix doped with phosphorescent green and yellow emitters. With this approach, we reach white color coordinates close to the standard illuminant A and a color rendering index of above 75. The presented devices are characterized by high luminous efficacies of above 30 lm/W on standard glass substrates without outcoupling enhancement.

Pyridine-Incorporated Dihexylquaterthiophene: A Novel Blue Emitter for Organic Light Emitting Diodes (OLEDs)

2012 ◽  
Vol 65 (9) ◽  
pp. 1244 ◽  
Author(s):  
Prashant Sonar ◽  
Sonsoles Garcia Santamaria ◽  
Ting Ting Lin ◽  
Alan Sellinger ◽  
Henk Bolink
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Organic Light Emitting Diodes ◽  
High Yield ◽  
Device Performance ◽  
Host Matrix ◽  
Maximum Brightness ◽  
Light Emitting ◽  
Organic Light ◽  
Processing Techniques

The synthesis and characterisation of 2,5-bis(5′-hexyl-[2,2′-bithiophen]-5-yl)pyridine (Th4PY) and its use as a blue emitter in organic light emitting diodes (OLEDs) is reported. Th4PY was synthesised in high yield using a straightforward Suzuki coupling route with commercially available starting materials. As Th4PY is both soluble and has low molecular weight, blue OLEDs were fabricated using both spin-coating and vacuum deposition thin film processing techniques to study the effect of processing on device performance. OLED devices using a spin-coated layer consisting of 4′,4′′-tris(N-carbazolyl)triphenylamine (TCTA) and 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) as a host matrix together with Th4PY as emitter exhibited highly efficient sky-blue emission with a low turn-on voltage of 3 V, a maximum brightness close to 15000 cd m–2 at 8 V, and a maximum luminous efficiency of 7.4 cd A–1 (6.3 lm W–1) with CIE coordinates of x = 0.212, y = 0.320. The device performance characteristics are compared using various matrices and processing techniques. The promising sky-blue OLED performance, solution processability, and ambient stability make Th4PY a promising blue emitter for application in OLEDs.

Quasi‐2D CsPbBr x I 3− x Composite Thin Films for Efficient and Stable Red Perovskite Light‐Emitting Diodes

2021 ◽  
pp. 2101419
Author(s):  
Ping Liu ◽  
Wanqing Cai ◽  
Cong Zhao ◽  
Siwei Zhang ◽  
Pengbo Nie ◽  
...  
Keyword(s):  
Thin Films ◽  
Light Emitting Diodes ◽  
Composite Thin Films ◽  
Light Emitting

Synthesis of Red Luminescent Non Symmetric Styryl-4H-Pyran-4-Ylidene Fragment Containing Derivatives for Organic Light-Emitting Diodes

2011 ◽  
Vol 222 ◽  
pp. 271-274 ◽  
Author(s):  
Elmars Zarins ◽  
Janis Jubels ◽  
Valdis Kokars
Keyword(s):  
Organic Solvents ◽  
Spectral Properties ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Amorphous Films ◽  
Light Emitting ◽  
Organic Light ◽  
Volatile Organic ◽  
Derivatives Of

New organic glassy non symmetric styryl- derivatives of 2(2,6-substituted-4H-pyran-4-ylidene)-malononitrile, 2(2,6-substituted-4H-pyran-4-ylidene)-1H-indene-1,3(2H)-dione and 2(2,6-substituted-4H-pyran-4-ylidene)-pyrimidine-2,4,6(1H,3H,5H)-trione were synthesized. They form thin solid amorphous films from volatile organic solvents (DCM and chloroform). Their spectral properties have been studied.

Sign in / Sign up

Export Citation Format

Share Document