Photoluminescence and Electroluminescence Quenching in 8-Hydroxyquinoline Aluminum Chelates

1995 ◽  
Vol 413 ◽  
Author(s):  
Xian-man Zhang ◽  
Keith A. Higginson ◽  
Fotios Papadimitrakopoulos
Keyword(s):  
Molecular Orbital ◽  
Elevated Temperatures ◽  
Light Emitting Diode ◽  
Condensation Reaction ◽  
Energy Levels ◽  
Polymeric Compound ◽  
Light Emitting ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital ◽  
Pl Quenching

ABSTRACTThe present communication proposes a mechanism for photoluminescence (PL) and electroluminescence (EL) quenching in aluminum(III) 8-hydroxyquinoline (Alq3) chelates. Our experiments indicate that in the presence of moisture, ligand exchange of 8-hydroxyquinoline with water can occur. At elevated temperatures, the liberated 8-hydroxyquinoline undergoes a condensation reaction in the presence of traces of oxygen, generating a dark, non-emissive polymeric compound. Spectroscopic and electrochemical methods were used to determine the band gap and energy levels (highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO)) of this byproduct. Steady state PL experiments indicate that (0.5 to 1%) concentration of this byproduct, evenly dispersed in Alq3 films, results in dramatic PL quenching. Deliberate insertion of an approximately 50 Å thick film of this byproduct into the interface of a poly(p-phenylenevinylene)/Alq3 light emitting diode (LED) completely quenches the EL as well. Initial data suggest an energy transfer quenching mechanism.

Electrochemistry, a Useful Tool in the Synthesis of Oligothiophenes

2021 ◽  
Vol 25 ◽  
Author(s):  
Fabiana Pandolfi ◽  
Martina Bortolami ◽  
Marta Feroci ◽  
Leonardo Mattiello ◽  
Vincenzo Scarano ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Organic Semiconductors ◽  
Organic Solar Cells ◽  
Field Effect Transistors ◽  
Energy Levels ◽  
Organic Field Effect Transistors ◽  
Light Emitting ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital ◽  
Organic Photodetectors

: Thiophene derivatives, either "small molecules," oligomers or polymers, play a role of primary importance among organic semiconductors. Therefore they have numerous and different technological applications in the field of Organic Electronics. For this reason, thiophene-based materials are found in devices such as organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), organic solar cells (OSCs), organic photodetectors, and many others. Oligothiophenes and polythiophenes have in common excellent charge transport properties and synthetic procedures that are now well established. Furthermore, oligothiophenes do not possess the intrinsic disadvantages of polythiophenes, such as the lack of well-defined structures and the inevitable presence of impurities. Electrochemistry can give a significant contribution to the field of oligothiophenes not only by allowing the determination of the highest-occupied molecular orbital (HOMO) and the lowest-unoccupied molecular orbital (LUMO) energy levels by the means of cyclic voltammetry (CV), but also rendering oligothiophenes syntheses more expeditious in comparison with the classical organic ones. This review outlines the application of electrochemistry techniques to the synthesis of oligothiophene derivatives.

Porphyrin doping of dichloride-bis(5,7-dichloroquinolin-8-olato)tin(IV) complex for electroluminescence

2013 ◽  
Vol 17 (05) ◽  
pp. 351-358 ◽  
Author(s):  
Mohammad Janghouri ◽  
Ezeddin Mohajerani ◽  
Mostafa M. Amini ◽  
Naser Safari
Keyword(s):  
Molecular Orbital ◽  
Light Emitting Diode ◽  
Low Cost ◽  
Energy Levels ◽  
Orbital Energy ◽  
Homogeneous Layer ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Fundamental Structure ◽  
Organic Light

A method for obtaining red emission from an organic-light emitting diode has been developed by dissolving red and yellow dyes in a common solvent and thermally evaporating the mixture in a single furnace. Dichlorido-bis(5,7-dichloroquinolin-8-olato)tin(IV) complex ( Q2SnCl2 , Q = 5,7-dichloro-8-hydroxyquinoline) has been synthesized for using as a fluorescent material in organic light-emitting diodes (OLEDs). The electronic states HOMO (Highest Occupied Molecular Orbital)/LUMO (Lowest Occupied Molecular Orbital) energy levels explored by means of cyclic voltammetry measurements. A device with fundamental structure of ITO/PEDOT:PSS (55nm)/PVK (90nm)/ Q2SnCl2/Al (180nm) was fabricated and its electroluminescence performance at various thicknesses of light emitting layer (LEL) of Q2SnCl2 is reported. By following this step, an optimal thickness for the doping effect was also identified and explained. Finally a device with fundamental structure of ITO/PEDOT:PSS (55nm)/PVK (90nm)/meso-tetraphenylporphyrin (TPP): Q2SnCl2 (75nm)/ Al (180nm) was fabricated and its electroluminescence performance at various concentrations of dye has been investigated. It is shown that this new method is promising candidate for fabrication of low cost OLEDs at more homogeneous layer.

scholarly journals Emphasizing the Operational Role of a Novel Graphene-Based Ink into High Performance Ternary Organic Solar Cells

2019 ◽  
Author(s):  
Minas M. Stylianakis ◽  
Dimitriοs M. Kosmidis ◽  
Katerina Anagnostou ◽  
Christos Polyzoidis ◽  
Miron Krassas ◽  
...  
Keyword(s):  
Solar Cells ◽  
Molecular Orbital ◽  
Organic Solar Cells ◽  
High Performance ◽  
Energy Levels ◽  
Fullerene Derivative ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital ◽  
Synthetic Routes

A novel solution-processed graphene-based material was synthesized by treating graphene oxide (GO) with 2,5,7-trinitro-9-oxo-fluorenone-4-carboxylic acid (TNF-COOH) moieties, via simple synthetic routes. The yielded molecule N-[(carbamoyl-GO)ethyl]-N’-[(carbamoyl)-(2,5,7-trinitro-9-oxo-fluorene)] (GO-TNF) was thoroughly characterized and it was shown that it presents favorable highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels to function as a bridge component between the polymeric donor poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl}) (PTB7) and the fullerene derivative acceptor [6,6]-phenyl-C71-butyric-acid-methylester (PC71BM). In this context, a GO-TNF based ink was prepared and directly incorporated within the binary photoactive layer, in different volume ratios (1-3% ratio to the blend), for the effective realization of inverted ternary organic solar cells (OSCs) of the structure ITO/PFN/PTB7:GO-TNF:PC71BM/MoO3/Al. The addition of 2% v/v GO-TNF ink led to a champion power conversion efficiency (PCE) of 8.71% that was enhanced by ~13% as compared to the reference cell.

Synthesis, crystal structure and photophysical properties of 1,4-bis(1,3-diazaazulen-2-yl)benzene: a new π building block

2018 ◽  
Vol 74 (2) ◽  
pp. 171-176
Author(s):  
Peili Sun ◽  
Zongyao Zhang ◽  
Hongxia Luo ◽  
Pu Zhang ◽  
Yujun Qin ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Building Block ◽  
Photophysical Properties ◽  
Condensation Reaction ◽  
Energy Levels ◽  
Three Dimensional ◽  
Experimental Result ◽  
Monoclinic System ◽  
H Nmr ◽  
Lowest Unoccupied Molecular Orbital

A dimerized 1,3-diazaazulene derivative, namely 1,4-bis(1,3-diazaazulen-2-yl)benzene [or 2,2′-(1,4-phenylene)bis(1,3-diazaazulene)], C22H14N4, (I), has been synthesized successfully through the condensation reaction between 2-methoxytropone and benzene-1,4-dicarboximidamide hydrochloride, and was characterized by 1H NMR and 13C NMR spectroscopies, and ESI–MS. X-ray diffraction analysis reveals that (I) has a nearly planar structure with good π-electron delocalization, indicating that it might serve as a π building block. The crystal belongs to the monoclinic system. One-dimensional chains were formed along the a axis through π–π interactions and adjacent chains are stabilized by C—H...N interactions, forming a three-dimensional architecture. The solid emission of (I) in the crystalline form exhibited a 170 nm red shift compared with that in the solution state. The observed optical bandgap for (I) is 3.22 eV and a cyclic voltammetry experiment confirmed the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The calculated bandgap for (I) is 3.37 eV, which is very close to the experimental result. In addition, the polarizability and hyperpolarizability of (I) were appraised for its further application in second-order nonlinear optical materials.

2,2′-[(Disulfanediyl)bis{5-[(1E)-(2-hydroxybenzylidene)amino]-1,3-thiazole-4,2-diyl}]diphenol: synthesis, crystal structure and calculation of molecular hyperpolarizability

2017 ◽  
Vol 73 (8) ◽  
pp. 609-612 ◽  
Author(s):  
Seyed Amir Zarei ◽  
Mohammad Piltan ◽  
Asmar Mashhun ◽  
Hadi Amiri Rudbari ◽  
Giuseppe Bruno
Keyword(s):  
Molecular Orbital ◽  
Condensation Reaction ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Highest Occupied Molecular Orbital ◽  
Molecular Hyperpolarizability ◽  
Lowest Unoccupied Molecular Orbital ◽  
Ir Spectroscopic ◽  
Base Compound

The title Schiff base compound {systematic name: 2-[5-[(E)-(2-hydroxybenzylidene)amino]-4-(2-{5-[(E)-(2-hydroxybenzylidene)amino]-2-(2-hydroxyphenyl)-1,3-thiazol-4-yl}disulfanyl)-1,3-thiazol-2-yl]phenol}, C32H22N4O4S4, incorporating a disulfanediyl (dithio) linkage, was obtained from the condensation reaction between two equivalents of salicylaldehyde and one equivalent of dithiooxamide in dimethylformamide, and was characterized by elemental analysis, IR spectroscopic analysis and single-crystal X-ray diffraction. A one-dimensional chain is formed along the b axis via double intermolecular C—H...S hydrogen bonds. The HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies and some related molecular parameters were calculated at the B3LYP/6-311G(d,p) level of theory. The molecular hyperpolarizability was also calculated.

scholarly journals An Effective D-π-A Type Donor Material Based on 4-Fluorobenzoylacetonitrile Core Unit for Bulk Heterojunction Organic Solar Cells

2021 ◽  
Vol 11 (2) ◽  
pp. 646
Author(s):  
Shabaz Alam ◽  
M. Shaheer Akhtar ◽  
Abdullah ◽  
Eun-Bi Kim ◽  
Hyung-Shik Shin ◽  
...  
Keyword(s):  
Solar Cells ◽  
Molecular Orbital ◽  
Organic Solar Cells ◽  
High Performance ◽  
Bulk Heterojunction ◽  
Energy Levels ◽  
Photovoltaic Properties ◽  
Donor Material ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

In order to develop new and effective donor materials, a planar donor-π-acceptor (D-π-A) type small organic molecule (SOM), 2-(4-fluorobenzoyl)-3-(5″-hexyl-[2,2′:5′,2″-terthiophen]-5-yl) acrylonitrile, named as H3T-4-FOP, was synthesized by the reaction of 4-fluorobenzoylacetonitrile (as acceptor unit) and hexyl terthiophene (as donor unit) derivatives. Promising optical, solubility, electronic and photovoltaic properties were observed for the H3T-4-FOP SOM. Significantly, the presence of 4-fluorobenzoylacetonitrile as an acceptor unit in H3T-4-FOP SOM tuned the optical band gap to ~2.01 eV and procured the reasonable energy levels as highest occupied molecular orbital (HOMO) of −5.27 eV and lowest unoccupied molecular orbital (LUMO) −3.26 eV. The synthesized H3T-4-FOP SOM was applied as a donor material to fabricate solution-processed bulk heterojunction organic solar cells (BHJ-OSCs) with an active layer of H3T-4-FOP: PC61BM (1:2, w/w) and was validated as having a good power conversion efficiency (PCE) of ~4.38%. Our studies clearly inspire for future designing of multifunctional groups containing the 4-fluorobenzoylacetonitrile based SOM for high performance BHJ-OSCs.

Impact of side-chain fluorination on photovoltaic properties: fine tuning of the microstructure and energy levels of 2D-conjugated copolymers

2017 ◽  
Vol 5 (32) ◽  
pp. 16702-16711 ◽  
Author(s):  
Jisoo Shin ◽  
Min Kim ◽  
Boseok Kang ◽  
Jaewon Lee ◽  
Heung Gyu Kim ◽  
...  
Keyword(s):  
Solar Cells ◽  
Molecular Orbital ◽  
Polymer Solar Cells ◽  
Energy Levels ◽  
Fine Tuning ◽  
Side Chain ◽  
Photovoltaic Properties ◽  
Highly Efficient ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The control of the molecular energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is crucial to the design of highly efficient polymer solar cells (PSCs).

scholarly journals Effect of Host Moieties on the Phosphorescent Spectrum of Green Platinum Complex

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 454 ◽  
Author(s):  
Yukiko Iwasaki ◽  
Hirohiko Fukagawa ◽  
Takahisa Shimizu
Keyword(s):  
Emission Spectrum ◽  
Molecular Orbital ◽  
Platinum Complex ◽  
Delayed Fluorescence ◽  
Molecular Structures ◽  
Light Emitting ◽  
Exciplex Formation ◽  
Highest Occupied Molecular Orbital ◽  
Wide Color Gamut ◽  
Lowest Unoccupied Molecular Orbital

Highly efficient, operationally stable, and pure-color organic light-emitting diodes (OLEDs) are of considerable significance for developing practical wide-color-gamut displays. Further, we have demonstrated the feasibility of an efficient pure green phosphorescent OLED (PHOLED) by employing a narrow-band platinum complex and a top-emitting structure. The utilization of the thermally activated delayed fluorescence (TADF) material as the phosphorescent host is expected to serve as a promising solution for obtaining operationally stable PHOLEDs with high color purity. However, the emission spectrum of the platinum complex in the TADF host exhibits a considerably broad emission spectrum. This study investigates the cause of the spectral change by evaluating the photoluminescence spectra of the platinum complex in various hosts exhibiting different molecular structures. The triazine unit in the host material was observed to result in exciplex formation between the lowest unoccupied molecular orbital (LUMO) of the host and the highest occupied molecular orbital (HOMO) of the platinum complex. Therefore, the TADF material that sterically hinders the triazine unit is considered to be suitable to prevent both exciplex formation and spectral broadening.

scholarly journals Detailed analytical studies of 1,2,4-triazole derivatized quinoline

2019 ◽  
Vol 10 (4) ◽  
pp. 281-294 ◽  
Author(s):  
Shilpa Mallappa Somagond ◽  
Manjunath Ningappa Wari ◽  
Saba Kauser Jaweed Shaikh ◽  
Sanjeev Ramchandra Inamdar ◽  
Madan Kumar Shankar ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Active Sites ◽  
Density Functional ◽  
Energy Gap ◽  
Energy Levels ◽  
Visual Image ◽  
Monoclinic Space Group ◽  
Charge Delocalization ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The present study describes, the X-ray single crystal analysis of 4-((2-chloro-6-methoxyquinolin-3-yl)methyl)-2-phenyl-2H-1,2,4-triazol-3(4H)-one (TMQ). The crystal data for C19H15ClN4O2: monoclinic, space group P21/n (no. 14), a = 7.3314(15) Å, b = 12.459(3) Å, c = 18.948(4) Å, β = 98.322(9)°, V = 1712.5(6) Å3, Z = 4, T = 296.15 K, μ(MoKα) = 0.245 mm-1, Dcalc = 1.423 g/cm3, 5082 reflections measured (3.926° ≤ 2Θ ≤ 38.556°), 1428 unique (Rint = 0.0545, Rsigma = 0.0574) which were used in all calculations. The final R1 was 0.0423 (I >2σ(I)) and wR2 was 0.1145 (all data). The Density functional theory optimized molecular geometries in TMQ agree closely with those obtained from crystallographic studies. The Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energy levels and energy gap were calculated by experimental (UV absorption & Cyclic voltammetry) and theoretical studies in two different solvents. The natural bond orbital analysis was performed to understand the molecular interaction on the basis of stability of molecule arising from hyper-conjugative interaction and charge delocalization. Hirshfeld surface and their related fingerprint plots enabled the identification of significant intermolecular interaction. The molecular electrostatic potential analysis provides the visual image of the chemically active sites and comparable reaction of atoms.

scholarly journals PffBT4T-2OD Based Solar Cells with Aryl-Substituted N-Methyl-Fulleropyrrolidine Acceptors

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4100 ◽  
Author(s):  
Hugo Gaspar ◽  
Flávio Figueira ◽  
Karol Strutyński ◽  
Manuel Melle-Franco ◽  
Dzmitry Ivanou ◽  
...  
Keyword(s):  
Solar Cells ◽  
Molecular Orbital ◽  
Density Functional ◽  
Polymer Solar Cells ◽  
Energy Levels ◽  
The Novel ◽  
Functional Theory ◽  
Reduction Potentials ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Novel C60 and C70 N-methyl-fulleropyrrolidine derivatives, containing both electron withdrawing and electron donating substituent groups, were synthesized by the well-known Prato reaction. The corresponding highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energy levels were determined by cyclic voltammetry, from the onset oxidation and reduction potentials, respectively. Some of the novel fullerenes have higher LUMO levels than the standards PC61BM and PC71BM. When tested in PffBT4T-2OD based polymer solar cells, with the standard architecture ITO/PEDOT:PSS/Active-Layer/Ca/Al, these fullerenes do not bring about any efficiency improvements compared to the standard PC71BM system, however they show how the electronic nature of the different substituents strongly affects the efficiency of the corresponding organic photovoltaic (OPV) devices. The functionalization of C70 yields a mixture of regioisomers and density functional theory (DFT) calculations show that these have systematically different electronic properties. This electronic inhomogeneity is likely responsible for the lower performance observed in devices containing C70 derivatives. These results help to understand how new fullerene acceptors can affect the performance of OPV devices.

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