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Alignment of charge-transfer complexes for molecular devices
Abstract
Charged cationic cyclometalated iridium(III) polypyridine complexes were electrostatically aligned and we found a regular packing of molecules with enhanced carrier mobility.
... Furthermore, as the 2 F 5/2 ← 2 F 7/2 , there is a moderateintensity transition. 64 Lastly, zeolite or polyoxometallate frameworks that are embellished with someone or comprise organic chromophores may also be utilized to incorporate Er 3+ ions. Undoubtedly these options will be carefully explored in the near future. ...
The manuscript reviews the implications of rare-earth elements, which comprise an important class of material and are essential for numerous technological improvements, and how research has gradually advanced due to their peculiar chemical and physical characteristics. The implications of their versatility will encourage the development of energy-efficient technological innovations. Interestingly, materials based on rare-earth elements have been closely studied in conjunction with several contemporary biologically-based technological advances and targeted therapies, to adequately overcome neurological problems. We provide a thorough overview of the multiple effects of materials made of rare earth’s, especially within the field of neuroscience research.
... It is known that the strongerinteraction leads to better charge transport property of organic semiconductor. 17 The charge carrier mobility of HOX and HOEP films ͑ϳ500 nm͒ were measured by time-of-flight technique. The hole carrier mobility of HOX ͑8 ϫ 10 −4 cm 2 / V s͒ was found to be ϳ27 times as that of HOEP ͑3 ϫ 10 −5 cm 2 / V s͒ which is consistent with our previous study of HOX and HOEP based field-effect transistor. ...
We study the effect of molecular alignment on the performance of organic photovoltaic devices (OPV) by using two porphyrin molecules of etioporphyrin-I (HOX) and octaethylporphyrin (HOEP) with similar chemical structures. Due to the minor differences in their peripheral substituents, the two porphyrin molecules form crystalline films of different molecular alignment. This has been verified by broader and redshift in the UV-vis absorption spectra as well as the grazing incidence x-ray diffraction of the films. OPV devices fabricated with these films show different performance. Stronger π-π stacking of HOX molecules exhibited better charge transport and photovoltaic performance than that of HOEP molecules.
A novel Ni(II) coordination polymer with flexible 4,4′-oxybis(benzoic acid) (oba) and rigid 4,4′-bipyridine was prepared hydrothermally and crystallographically characterized. It shows an unusual μ-oxo(O2−) bridged dinickel(II) polymer. In the dimetal core, each metal center is six-coordinated to three carboxylate oxygen atoms from two different oba ligands, two nitrogen atoms of distinct 4,4′-bipyridine and one bridging oxygen forming a distorted octahedron.Upon complexation, nickel complex exhibits intense purple fluorescence (413.8 nm) which may originates to the O2−Ni2+(LMCT) in addition to the peaks of intraligand π–π∗ transition of oba ligand (317.7 and 720.7 nm). Moreover, nickel crystals possess preferable photocatalytic decomposition of RhB solution.
Liquid crystal based sulfonic acid, 4-(octadecyloxy)phenylsulfonic acid, 1, effectively transportsprotons at 80 °C under non-humidified conditions. At its smectic A liquid crystal state, the proton conductivity of 1 was measured to be 1.1 × 10−2 S cm−1. The proton conductivities of 1 at its molten and solid powder states were found to be 1.2 × 10−4 and 1.5 × 10−7 S cm−1, respectively. A lamellar structure of bilayer stacks of 1 with the sulfonic acidgroups in a head-to-head configuration was found within the monodomain of SmA phase of 1 from in situ XRD and DFT calculation. We proposed that the efficient proton transporting property of 1 is highly correlated to the formation of supramolecular pathways between the molecules at its liquid crystal phase.
Ionic transition metal complexes (iTMCs) are receiving increased attention as materials capable of yielding efficient electroluminescent devices with air-stable electrodes. The operational characteristics of these devices are dominated by the presence of mobile ions that redistribute under an applied bias and assist in electronic charge injection. This article reviews recent efforts in the field of iTMC devices: i) to understand their physics, ii) to improve their efficiency, colour, turn-on time and lifetime, and iii) to expose their potential applications.
30 years of IrIII coordination chemistry with
polyimine-type ligands are summarized. Over the years, milder reaction
conditions have been used for their synthesis, allowing the incorporation
of various functional substituents. Complexes are described with bidentate
and terdentate ligands, with both N- and C-donor sites. All complexes are
luminescent, with predominantly charge-transfer or ligand-centred emissive
states depending on the charge density donated from the ligands to the
metal. IrIII excited state lifetimes range from nanoseconds to
microseconds. A wide range of properties are obtained:
[IrN6]3+ complexes are strong photooxidants while
tris-cyclometallated [IrN3C3] complexes are strong
photoreductants.
Through gate-modulated electrochemical doping, ambipolar operation in thin-film transistors (TFTs) can be realized in air with solution processable conjugated polymers. Unlike other typical organic TFTs, which rely on high crystallinity for better charge transport, these electrochemically-doped transistors operate under a different mechanism and show very high current output even with completely amorphous polymers. © 2001 American Institute of Physics.
A series of new luminescent organoiridium(III) polypyridine complexes [Ir(N−C)2(N−N)](PF6) (HN−C = 2-phenylpyridine, Hppy, N−N = 4-n-octadecylaminocarbonyl-4′-methyl-2,2′-bipyridine (Me-bpy-CONH-C18H37) (1a), 4-n-decylaminocarbonyl-4′-methyl-2,2′-bipyridine (Me-bpy-CONH-C10H21) (1b), 4-ethylaminocarbonyl-4′-methyl-2,2′-bipyridine (Me-bpy-CONH-C2H5) (1c); HN−C = 1-phenylpyrazole, Hppz, N−N = Me-bpy-CONH-C18H37 (2a), Me-bpy-CONH-C10H21 (2b), Me-bpy-CONH-C2H5 (2c); HN−C = 2-phenylquinoline, Hpq, N−N = Me-bpy-CONH-C18H37 (3a), Me-bpy-CONH-C10H21 (3b), Me-bpy-CONH-C2H5 (3c)) bearing an alkyl pendant have been synthesized and characterized. The photophysical and electrochemical properties of these complexes have been investigated. Upon irradiation, all the complexes exhibited intense and long-lived luminescence in homogeneous fluid solutions at 298 K and in alcohol glass at 77 K. The emission has been assigned to a triplet metal-to-ligand charge-transfer (3MLCT) (dπ(Ir) → π*(diimine)) excited state. The emissive states of the pq complexes 3a−c are probably mixed with some triplet intraligand (3IL) (π → π*) (pq) character. All the complexes have been incorporated into phospholipid vesicles composed of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), and the resulting liposomes have been examined by cryogenic transmission electron microscopy (cryo-TEM) and luminescence spectroscopy. Also, the emission properties of the complexes in aqueous solutions containing the surfactants sodium dodecylsulfate (SDS), Triton X-100 (TX), and cetyltrimethylammonium bromide (CTAB) have been studied. The lipophilicity of the complexes has been determined by reversed-phase HPLC, and the log Po/w values were dependent on the cyclometalating and diimine ligands. Additionally, the cytotoxicity of these organoiridium(III) complexes toward the human cervix epithelioid carcinoma (HeLa) cell line has been evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, the cellular uptake of all the complexes by HeLa cells has been examined by flow cytometry and laser-scanning confocal microscopy.
Synthetic, structural, photophysical, and electrochemical characterizations of ortho-metalated (Ir(NC)/sub 2/Cl)/sub 2/ dimeric and (Ir(NC)/sub 2/NN)Cl monomeric complexes, where NC = 2(p-tolyl)pyridine (ptpy) or 3-methyl-2-phenylpyridine (mppy) and NN = 2,2'-bipyridine (bpy) are described. Structural characterizations by /sup 1/H and /sup 13/C nuclear magnetic resonance (NMR) indicate the presence of symmetry elements in these complexes. The ultraviolet-visible absorption properties of these complexes are reported. The results of voltametric measurements of these complexes are included. 55 references, 10 figures, 6 tables.
Organic thin film field effect transistors of water-soluble cationic and anionic phthalocyanine derivatives were successfully prepared using the layer-by-layer deposition technique. The alternating film growth and subsequent transistor properties were studied with a variety of techniques including ellipsometry, UV−vis spectroscopy, polarized UV−vis spectroscopy, AFM, and field effect transistor measurements. A stepwise and regular deposition of copper(II) phthalocyanine tetrakis(methyl pyridinium) chloride and copper(II) phthalocyanine tetrasulfonic acid, tetrasodium salt multilayers in both pure water and 0.03 M NaCl solution was observed. Differences in linear growth were observed between pure water and 0.03 M NaCl-based solutions. Polarized UV−vis spectra indicated that the conjugated phthalocyanine ring lies almost flat on the substrate surface with a random orientation within the plane of the substrate. Unusual “ambipolar” transistor-like behavior was found for the films that can be attributed to an ion-modulated electrical conduction mechanism, which relies on the assistance of mobile ions to stabilize the oxidized or reduced species in the channel region.
A bottom-up, self-aligned inkjet printing technique that is capable of defining sub- 100 nm critical features with two simple additive printing steps using standard ink-jet printing equipment without the need for any lithography or precise relative alignment, was analyzed. The conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT/PSS) was used for the ink of the first and second pattern. It was shown that the technique is likely to be equally applicable to other liquid-based, graphic arts printing techniques. It was found that the technique can be applied to a range of solution-processable functional materials, and might also be used in a subtractive mode.
In this contribution we review the motivations for, and recent advances in, new gate dielectric materials for incorporation into organic thin-film transistors (OTFTs) for organic electronics. After a general introduction to OTFT materials, operating principles, and processing requirements for optimizing low-cost organic electronics, this review focuses on three classes of OTFT-compatible dielectrics: i) inorganic (high-k) materials; ii) polymeric materials; and iii) self-assembled mono- and/multilayer materials. The principal goals in this active research area are tunable and reduced OTFT operating voltages, leading to decreased device power consumption while providing excellent dielectric/insulator properties and efficient low-cost solution-phase processing characteristics.
Organic thin film transistors (OTFTs) will play an important role in future plastic electronic devices. The device performance is greatly affected by the molecular structure and morphology of the organic semiconductors. Various methods for organic semiconductor deposition are reviewed. Recent progress in printing and patterning of OTFTs are also surveyed.
A printing-based approach to high-performance thin-film transistors supported on flexible substrates was studied by a large-area, selective transfer of microstructured silicon. In Method I, a peanut-shaped photoresist pattern was developed on top of a SOI substrate using standard photolithography techniques. Method II uses a masterless soft-lithography technique to chemically bond the μs-Si to a PDMS-coated substrate. After heating, the PDMS was peeled from the SOI, resulting in patterned transfer of μs-Si to the UVO-modified regions of the PDMS.
An overview is given on the excellent electrical properties of contacts in organic transistors and logic gates that use printed electrodes of DNNSA-PANI/SWNT in bottom contact configurations. The large grain sizes observed at and near the contacts are consistent with the observations. The results provide some evidence to suggest that thermal printing with this class of doped conducting polymer or related materials might represent progress toward a useful strategy for building large-area circuits for realistic applications.
Here, the photophysics and performance of single-layer light emitting cells (LECs) based on a series of ionic cyclometalated Ir(III) complexes of formulae [Ir(ppy)(2)(bpy)]+PF6- and [Ir(ppy)(2)(phen)]+PF6- where ppy, bpy, and phen are 2-phenylpyridine, substituted bipyridine and substituted phenanthroline ligands, respectively, are reported. Substitution at the N N Iigand has little effect on the emitting metal-ligand to ligand charge-transfer (MLLCT) states and functionalization at this site of the complex leads to only modest changes in emission color. For the more bulky complexes the increase in intermolecular separation leads to reduced exciton migration, which in turn, by suppressing concentration quenching, significantly increases the lifetime of the excited state. On the other hand, the larger intermolecular separation induced by bulky ligands reduces the charge carrier mobility of the materials, which means that higher bias fields are needed to drive the diodes. A brightness of ca. 1000cd m(-2) at 3 V is obtained for complex 5, which demonstrates a beneficial effect of bulky substituents.
Optoelectronic properties of light-emitting field-effect transistors (LETs) fabricated on bottom-contact transistor structures using a tetracene film as charge-transport and light-emitting material are investigated. Electroluminescence generation and transistor current are correlated, and the bias dependence of the LETs external quantum efficiency is determined. The device's performance degrade rapidly upon gate biasing. The effect is attributed to charge trapping, which can be prevented by operating the devices in pulsed mode.A model for the electron injection mechanism in a p-type organic transistor is proposed. On the basis of this model, electrical and optical characteristics, as well as the dependence of the external quantum efficiency on drain- and gate-bias, are well reproduced.
Weiche Materie mit hartem Kern: Durch PtII⋅⋅⋅PtII- und hydrophobe Wechselwirkungen gehen planare Organoplatin(II)-Kationen mit Chlorid- oder Sulfat-Gegenionen in Wasser in rot emittierende, viskoelastische, gestapelte Mesophasen über, aus denen leicht ausgerichtete Filme und uniaxiale Mikrofasern mit cofacialer Molekülanordnung erhalten werden.
Organometallic nanowires with luminescent and current-modulating properties were self-assembled from cyclometalated/ terpyridyl platinum(II) complexes with auxiliary arylisocyanide/arylacetylide ligands and incorporated into a compact organic light-emitting field-effect transistor (see picture) by solution-processable protocols. The nanowires exhibit both electron and hole mobilities of 0.1 cm2V-1 s-1. (Figure Presented).
The behavior of light-emitting electrochemical cells (LEC) based on solid films ( approximately 100 nm) of tris(2,2'-bipyridine)ruthenium(II) between an ITO anode and a Ga-In cathode was investigated. The response times were strongly influenced by the nature of the counterion: small anions (BF(4)(-) and ClO(4)(-)) led to relatively fast transients, while large anions (PF(6)(-), AsF(6)(-)) produced a slow time-response. From comparative experiments of cells prepared and tested in a glovebox to those in ambient, mobility of the anions in these films appears to be related to the presence of traces of water from atmospheric moisture. An electrochemical model is proposed to describe the behavior of these LECs. The simulation results agreed well with experimental transients of current and light emission as a function of time and show that the charge injection is asymmetric at the two electrodes. At a small bias, electrons are the major carriers, while for a larger bias the conduction becomes bipolar.
Polarized infrared optical emission was observed from a carbon nanotube ambipolar field-effect transistor (FET). An effective forward-biased p-n junction, without chemical dopants, was created in the nanotube by appropriately biasing the nanotube device. Electrical measurements show that the observed optical emission originates from radiative recombination of electrons and holes that are simultaneously injected into the undoped nanotube. These observations are consistent with a nanotube FET model in which thin Schottky barriers form at the source and drain contacts. This arrangement is a novel optical recombination radiation source in which the electrons and holes are injected into a nearly field-free region. Sucha source may form the basis for ultrasmall integrated photonic devices.
We report on the spectroscopic, electrochemical, and electroluminescent properties of [Ir(ppy)(2)(dtb-bpy)](+)(PF(6))(-) (ppy: 2-phenylpyridine, dtb-bpy: 4,4'-di-tert-butyl-2,2'-dipyridyl). Single-layer devices were fabricated and found to emit yellow light with a brightness that exceeds 300 cd/m(2) and a luminous power efficiency that exceeds 10 Lm/W at just 3 V. The PF(6)(-) space charge was found to dominate the device characteristics.
Six luminescent cyclometalated iridium(III)-dipyridoquinoxaline and -dipyridophenazine complexes [Ir(ppy)2(N-N)](PF6) (Hppy = 2-phenylpyridine; N-N = dipyrido[3,2-f:2',3'-h]quinoxaline, dpq (1); 2-n-butylamidodipyrido[3,2-f:2',3'-h]quinoxaline, dpqa (2); 2-((2-biotinamido)ethyl)amidodipyrido[3,2-f:2',3'-h]quinoxaline, dpqB (3); dipyrido[3,2-a:2',3'-c]phenazine, dppz (4); benzo[i]dipyrido[3,2-a:2',3'-c]phenazine, dppn (5); 11-((2-biotinamido)ethyl)amidodipyrido[3,2-a:2',3'-c]phenazine, dppzB (6)) have been designed as luminescent intercalators for DNA and probes for avidin. The structure of complex 4 has been studied by X-ray crystallography. The photophysical and electrochemical properties of the complexes have also been investigated. The binding of these complexes to double-stranded calf thymus DNA and synthetic double-stranded oligonucleotides poly(dA) x poly(dT) and poly(dG) x poly(dC) has been investigated by spectroscopic titrations. The interactions between the two biotin-containing complexes and avidin have been studied by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays and emission titrations.
White electroluminescent (EL) emission from single-layered solid-state light-emitting electrochemical cells (LECs) based on host-guest cationic iridium complexes has been successfully demonstrated. The devices show white EL spectra (Commission Internationale de l'Eclairage coordinates ranging from (x, y) = (0.45, 0.40) to (0.35, 0.39) at 2.9-3.3 V with high color rendering indices up to 80. Peak external quantum efficiency and peak power efficiency of the white LEC reach 4% and 7.8 lm/W, respectively. These results suggest that white LECs based on host-guest cationic transition metal complexes may be a promising alternative for solid-state lighting technologies.
Nanostructured monolayers of water-insoluble amphiphilic 5-alkoxy-isophthalic acids direct the reversible self-assembly of water-soluble positively and negatively charged molecules under electrochemical control. The surface potential is in control of the monolayer composition, structure, and guest dynamics.
Organic field-effect transistors incorporating planar pi-conjugated metal-free macrocycles and their metal derivatives are fabricated by vacuum deposition. The crystal structures of [H2(OX)] (H(2)OX=etioporphyrin-I), [Cu(OX)], [Pt(OX)], and [Pt(TBP)] (H2TBP=tetra-(n-butyl)porphyrin) as determined by single crystal X-ray diffraction (XRD), reveal the absence of occluded solvent molecules. The field-effect transistors (FETs) made from thin films of all these metal-free macrocycles and their metal derivatives show a p-type semiconductor behavior with a charge mobility (mu) ranging from 10(-6) to 10(-1) cm(2) V(-1) s(-1). Annealing the as-deposited Pt(OX) film leads to the formation of a polycrystalline film that exhibits excellent overall charge transport properties with a charge mobility of up to 3.2 x 10(-1) cm(2) V(-1) s(-1), which is the best value reported for a metalloporphyrin. Compared with their metal derivatives, the field-effect transistors made from thin films of metal-free macrocycles (except tetra-(n-propyl)porphycene) have significantly lower mu values (3.0 x 10(-6)-3.7 x 10(-5) cm(2) V(-1) s(-1)).
- H.-C Su
- H.-F Chen
- F.-C Fang
- C.-C Liu
- C.-C Wu
- K.-T Wong
- Y.-H Liu
- S.-M Peng
H.-C. Su, H.-F. Chen, F.-C. Fang, C.-C. Liu, C.-C. Wu, K.-T. Wong,
Y.-H. Liu and S.-M. Peng, J. Am. Chem. Soc., 2008, 130, 3413-3419.
- L Chen
- Z Bao
- J H Schon
- A J Lovinger
L. Chen, Z. Bao, J. H. Schon, A. J. Lovinger, Y.-Y. Lin, B. Crone,
A. Dodabalapur and B. Batlogg, Appl. Phys. Lett., 2001, 78, 228-230;
Organic Superconductors(including Fullerenes
- M Williams
M. Williams, Organic Superconductors(including Fullerenes,
Prentice Hall, Englewood Cliffs, NJ, 1992.
- R Santato
- M A Capelli
- M Loi
- F Murgia
- V A L Cicoira
- P Roy
- R Stallinga
- M Zamboni
- Muccini
Santato, R. Capelli, M. A. Loi, M. Murgia, F. Cicoira,
V. A. L. Roy, P. stallinga, R. Zamboni and M. Muccini, Synth.
Met., 2004, 146, 329-334.
- I M Dixon
- J.-P Collin
- J.-P Sauvage
- L Flamigini
- S Encinas
- F Barigelletti
I. M. Dixon, J.-P. Collin, J.-P. Sauvage, L. Flamigini, S. Encinas and
F. Barigelletti, Chem. Soc. Rev., 2000, 29, 385-391.
- K K W Lo
- P K Lee
- J S Y Lau
K. K. W. Lo, P. K. Lee and J. S. Y. Lau, Organometallics, 2008, 27,
2998-3006.
- C.-J Rothe
- V Chiang
- K Jankus
- X.-S Abdullah
- R Zeng
- A S Jitchati
- M R Batsanov
- A P Bryce
- Monkman
Rothe, C.-J. Chiang, V. Jankus, K. Abdullah, X.-S. Zeng,
R. Jitchati, A. S. Batsanov, M. R. Bryce and A. P. Monkman, Adv.
Funct. Mater., 2009, 19, 2038-7.
- K K W Lo
- C K Chung
- N Zhu
K. K. W. Lo, C. K. Chung and N. Zhu, Chem.-Eur. J., 2006, 12,
1500-1512.
- C.-M Che
- H F Xiang
- Z X Xu
- S Y Chui
- V A L Roy
- P T Lai
C.-M. Che, H. F. Xiang, Z. X. Xu, S. Y. Chui, V. A. L. Roy and
P. T. Lai, Chem.-Asian J., 2008, 3, 1092-1103.
- A Misewich
- R Martel
- Ph
- J C Avouris
- S Tsang
- J Heinze
- Tersoff
A. Misewich, R. Martel, Ph. Avouris, J. C. Tsang, S. Heinze and
J. Tersoff, Science, 2003, 300, 783.
- M.-H Facchetti
- T Yoon
- Marks
Facchetti, M.-H. Yoon and T. Marks, Adv. Mater., 2005, 17,
1705-1725.
- F O Garces
- K A King
- R J Watts
9 For complex 1: F. O. Garces, K. A. King and R. J. Watts, Inorg.
Chem., 1988, 27, 3464-3471; for complex 2: K. K. W. Lo, P. K. Lee
and J. S. Y. Lau, Organometallics, 2008, 27, 2998-3006; for
complex 3: K. K. W. Lo, C. K. Chung and N. Zhu, Chem.-Eur. J.,
2006, 12, 1500-1512.
- A Facchetti
- M.-H Yoon
- T Marks
A. Facchetti, M.-H. Yoon and T. Marks, Adv. Mater., 2005, 17,
1705-1725.
- J A Misewich
- R Martel
- Ph Avouris
- J C Tsang
- S Heinze
- J Tersoff
J. A. Misewich, R. Martel, Ph. Avouris, J. C. Tsang, S. Heinze and
J. Tersoff, Science, 2003, 300, 783.
- A S Klymchenko
- S Furukawa
- M V D Auweraer
- K Ullen
- S D Feyter
A. S. Klymchenko, S. Furukawa, M. V. D. Auweraer, K. M€ ullen and
S. D. Feyter, Nano Lett., 2008, 8, 1163-1168.
- C Rothe
- C.-J Chiang
- V Jankus
- K Abdullah
- X.-S Zeng
- R Jitchati
- A S Batsanov
- M R Bryce
- A P Monkman
C. Rothe, C.-J. Chiang, V. Jankus, K. Abdullah, X.-S. Zeng,
R. Jitchati, A. S. Batsanov, M. R. Bryce and A. P. Monkman, Adv.
Funct. Mater., 2009, 19, 2038-7.
- M.-Y Yuen
- V A L Roy
- W Lu
- S C F Kui
- G S M Tong
- M.-H So
- S S Chui
- M Muccini
- J Q Ning
- S J Xu
- C.-M Che
M.-Y. Yuen, V. A. L. Roy, W. Lu, S. C. F. Kui, G. S. M. Tong,
M.-H. So, S. S.-Y. Chui, M. Muccini, J. Q. Ning, S. J. Xu and
C.-M. Che, Angew. Chem., Int. Ed., 2008, 47, 9895; Wei Lu,
Yong Chen, V. A. L. Roy, Stephen Sin-Yin Chui and Chi-Ming Che, Angew. Chem., Int. Ed., 2009, 48, 7621-7625.
- J D Slinker
- J Rivnay
- J S Moskowitz
- J B Parker
- S Bernhard
- H D Abruña
- G G Malliaras
J. D. Slinker,
J. Rivnay, J. S. Moskowitz, J. B. Parker, S. Bernhard,
H. D. Abruña and G. G. Malliaras, J. Mater. Chem., 2007, 17,
2976-2988;