Chunhui Huang

Functional IrIII Complexes and Their Applications

Co-reporter:Zhu-qi Chen;Zu-qiang Bian ;Chun-hui Huang

Advanced Materials 2010 Volume 22( Issue 13) pp:1534-1539

Publication Date(Web):

DOI:10.1002/adma.200903233

Abstract

Iridium complexes are drawing great interest because they exhibit high phosphorescence quantum efficiency. Extensive efforts have been devoted to the molecular design of ligands to achieve phosphorescent emission over a wide range of wavelengths that is compatible with many applications. In this research news article, we focus on materials design to improve the performance of phosphorescent Ir^III complexes for organic light-emitting diodes (OLEDs), luminescence sensitizers, and biological imaging.

Sensitized luminescence from lanthanides in d–f bimetallic complexes

Co-reporter:Fang-Fang Chen, Zhu-Qi Chen, Zu-Qiang Bian, Chun-Hui Huang

Coordination Chemistry Reviews 2010 Volume 254(9–10) pp:991-1010

Publication Date(Web):May 2010

DOI:10.1016/j.ccr.2009.12.028

This article reviews progress in the research of transition metal–lanthanide (d–f) bimetallic complexes. Through efficient energy transfer, sensitized luminescence of lanthanide ions from the visible range (EuIII) to the near-infrared region (NdIII, YbIII, ErIII and PrIII) is obtained in these bimetallic assembles. The d-block in d–f bimetallic complexes mainly contributes to the improvement of lanthanide emission efficiency and the extension of the excitation window for the lanthanide complexes. Examples are catalogued by various transition metals, such as RuII, OsII (FeII), PtII (AuI), PdII, ReI, CrIII, CoIII, ZnII and IrIII. The relevant synthetic procedures, crystal structures and photophysical properties of these d–f complexes are briefly described. Additionally, the molecular properties responsible for the performance of certain d–f systems, such as energy levels, nuclear distances and coordination environments, will be discussed.

Highly efficient, orange–red organic light-emitting diodes using a series of green-emission iridium complexes as hosts

Co-reporter:Zhiwei Liu, Zuqiang Bian, Feng Hao, Daobo Nie, Fei Ding, Zhuqi Chen, Chunhui Huang

Organic Electronics 2009 Volume 10(Issue 2) pp:247-255

Publication Date(Web):April 2009

DOI:10.1016/j.orgel.2008.11.013

We investigated highly efficient phosphorescent organic light-emitting diodes (OLEDs) based on an orange–red emission iridium complex as the guest and five green emission iridium complexes as the host material, respectively. For comparison, a device using a common fluorescent host CBP (4,4′-bis(N-carbazolyl)-1,1′-biphenyl) has also been fabricated. Results show that the steric hindrance and exciton transporting property of the iridium complex host are found to be critical to this kind of doping system, a proper steric hindrance and improved exciton transporting ability result in reducing of triplet–triplet annihilation, thus improving of the device performance. In addition, all devices using iridium complexes as host have better performance than that of CBP, which arised from the fact that those green emission iridium complexes have a lower triplet excited energy befitting for energy confinement and a higher highest occupied molecular orbital (HOMO) level for hole injection.

A highly efficient OLED based on terbium complexes

Co-reporter:Zhuqi Chen, Fei Ding, Feng Hao, Zuqiang Bian, Bei Ding, Yezi Zhu, Fangfang Chen, Chunhui Huang

Organic Electronics 2009 Volume 10(Issue 5) pp:939-947

Publication Date(Web):August 2009

DOI:10.1016/j.orgel.2009.04.023

A neutral ligand 9-(4-tert-butylphenyl)-3,6-bis(diphenylphosphineoxide)-carbazole (DPPOC) and its complex Tb(PMIP)3DPPOC (A, where PMIP stands for 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone) were synthesized. DPPOC has a suitable lowest triplet energy level (24,691 cm−1) for the sensitization of Tb(III) (5D4: 20,400 cm−1) and a significantly higher thermal stability (glass transition temperature 137 °C) compared with the familiar ligand triphenylphosphine oxide (TPPO). Experiments revealed that the emission layer of the Tb(PMIP)3DPPOC film could be prepared by vacuum co-deposition of the complex Tb(PMIP)3(H2O)2 (B) and DPPOC (molar ratio = 1:1). The electroluminescent (EL) device ITO/N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-diphenyl-4,4′-diamine (NPB; 10 nm)/Tb(PMIP)3 (20 nm)/co-deposited Tb(PMIP)3DPPOC (30 nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP; 10 nm)/tris(8-hydroxyquinoline) (AlQ; 20 nm)/Mg0.9Ag0.1 (200 nm)/Ag (80 nm) exhibited pure emission from terbium ions, even at the highest current density. The highest efficiency obtained was 16.1 lm W−1, 36.0 cd A−1 at 6 V. At a practical brightness of 119 cd m−2 (11 V) the efficiency remained above 4.5 lm W−1, 15.7 cd A−1. These values are a significant improvement over the previously reported Tb(PMIP)3(TPPO)2 (C).

Inverted photovoltaic device based on ZnO and organic small molecule heterojunction

Co-reporter:J.P. Liu, S.S. Wang, Z.Q. Bian, M.N. Shan, C.H. Huang

Chemical Physics Letters 2009 Volume 470(1–3) pp:103-106

Publication Date(Web):24 February 2009

DOI:10.1016/j.cplett.2009.01.033

The solar cells with an inverted structure of indium tin oxide (ITO)/ZnO/copper-phthalocyanine (CuPc):fullerene (C60)/CuPc/poly(3,4-oxyethyleneoxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/Ag were fabricated. The current density–voltage curve indicates that ZnO was a highly effective electron-selective contact and plays important roles on the rectification behavior and the photovoltaic performance improvement. The incident photo to current conversion efficiency combined with the absorption spectrum indicates that most of the photocurrent generation was attributed to the excitation of CuPc. The shelf lifetime of unencapsulated devices was over 900 h in air due to the inverted structure which gives a promising way for fabrication of solar cells with improved stability.The ZnO interlayer is the key factor for the formation of p–n heterojunction to obtain rectification behavior and photovoltaic performance.

Synthesis of Amphiphilic Dye-Self-Assembled Mesostructured Powder Silica with Enhanced Emission for Directional Random Laser

Co-reporter:Kun Hou, Qinghai Song, Daobo Nie, Fuyou Li, Zuqiang Bian, Liying Liu, Lei Xu and Chunhui Huang

Chemistry of Materials 2008 Volume 20(Issue 12) pp:3814

Publication Date(Web):May 27, 2008

DOI:10.1021/cm703023d

In this paper, we report a laser device application of dye-self-assembled mesostructured powder. Dye-assembled submicrometer-sized mesostrucutred silica with high luminescence was first synthesized at room temperature from a mixed-surfactant system comprising laboratory synthesized hemicyanine dye and cetyltrimethylammounium bromide (CTAB) as structure-directing agents. The fluorescence emission of the dye molecules was greatly enhanced when self-assembled into the mesostructred powder even though the dye concentration is very high. The highly luminescent powder was further used as gain media to fabricate a laser device. The laser device is a combination of planar microcavity with mesostructured powder random gain layer. Investigation of the laser performance employing the mesostructured powder with enhanced emission as gain media shows a directional output and a much lower threshold, which is 85 times lower than counterpart device using a mixture of silica sphere and dye molecules as gain media.

Highly Efficient Sensitized Red Emission from Europium (III) in Ir−Eu Bimetallic Complexes by 3MLCT Energy Transfer

Co-reporter:Fang-Fang Chen ; Zu-Qiang Bian ; Zhi-Wei Liu ; Dao-Bo Nie ; Zhu-Qi Chen ;Chun-Hui Huang

Inorganic Chemistry 2008 Volume 47(Issue 7) pp:2507-2513

Publication Date(Web):February 27, 2008

DOI:10.1021/ic701817n

Two novel iridium−europium bimetallic complexes, {[(dfppy)2Ir(μ-phen5f)]3EuCl}Cl2 and (dfppy)2Ir(μ-phen5f)Eu(TFAcA)3 [dfppy represents 2-(4′,6′-difluorophenyl)-pyridinato-N,C2′, phen5f stands for 4,4,5,5,5-pentafluoro-1-(1′,10′-phenanthrolin-2′-yl)-pentane-1,3-dionate and TFAcA represents trifluoroacetylacetonate], were successfully synthesized. The novel ligand Hphen5f with four coordination sites was designed as a bridge to link the IrIII center and the EuIII center. The X-ray diffraction data shows that the nonbonding distances for Eu···Ir are 6.028, 5.907, and 6.100 Å in the bimetallic complex {[(dfppy)2Ir(μ-phen5f)]3EuCl}Cl2. Photophysical studies implied that the high efficient red luminescence from the EuIII ion was sensitized by the 3MLCT (metal-to-ligand charge transfer) energy based on an IrIII complex-ligand in a d-f bimetallic assembly. The excitation window for the new bimetallic complex {[(dfppy)2Ir(μ-phen5f)]3EuCl}Cl2 extends up to 530 nm (1 × 10−3 M in EtOH), indicating that this bimetallic complex can emit red light under the irradiation of sunlight.

Acetonitrile-Vapor-Induced Color and Luminescence Changes in a Cyclometalated Heteroleptic Iridium Complex

Co-reporter:Zhiwei Liu ; Zuqiang Bian ; Jiang Bian ; Zhendong Li ; Daobo Nie

Inorganic Chemistry 2008 Volume 47(Issue 18) pp:8025-8030

Publication Date(Web):August 9, 2008

DOI:10.1021/ic702141h

An iridium complex PIr(qnx) (iridium(III) bis(2-phenylpyridinato-N,C2)(quinoxaline-2-carboxylate)) is reported for its unique and fast vapochromic and vapoluminescent behaviors. The emission of PIr(qnx) is governed by the whole crystal rather than the individual molecule. PIr(qnx) has been found to exist as both black and red forms in the solid state. The black form can be transformed into the red form upon its exposure to acetonitrile or propiononitrile vapor, whereas no response was observed when it was exposed to other volatile organic compounds. To understand the vapochromic and vapoluminescent behaviors, we determined crystal structures of both forms by X-ray diffraction. In addition, we employed density functional theory in investigating weak intermolecular interactions, such as hydrogen bonding and π−π interactions in the two forms.

Sensitised near-infrared emission from lanthanides using an iridium complex as a ligand in heteronuclear Ir2Ln arrays

Co-reporter:Fang-Fang Chen, Zu-Qiang Bian, Bin Lou , En Ma, Zhi-Wei Liu, Dao-Bo Nie, Zhu-Qi Chen, Jiang Bian, Zhong-Ning Chen and Chun-Hui Huang

Dalton Transactions 2008 (Issue 41) pp:5577-5583

Publication Date(Web):09 Sep 2008

DOI:10.1039/B810016K

The iridium(III) complex Ir(ppy)2(phen5f) [ppy = 2-phenylpyridinato-N,C2′, and phen5f = 4,4,5,5,5-pentafluoro-1-(1′,10′-phenanthrolin-2′-yl)-pentane-1,3-dionate] has been synthesised and used as “complex ligands” to make heteronuclear d–f complexes by the attachment of Ln(NO3)3·xH2O at the vacant coordination sites in the bridging ligand phen5f. The microanalyses and crystal structure characteristics confirmed the formation of the heteronuclear Ir2Ln arrays. The measurement of the lowest triplet state energy level of Ir(ppy)2(phen5f) indicates that it is suitable for the NIR (near-infrared) lanthanide ions, NdIII, YbIIIand ErIII. Upon irradiation of the MLCT (metal-to-ligand charge transfer) absorption of Ir(ppy)2(phen5f) at an excitation wavelength from 380–490 nm, the characteristic emission spectra of the three Ir2Ln arrays (Ln = Nd, Yb, Er) in both the solid state and in CH3CN solution were measured. According to the results, more IrIII complexes will be designed for lanthanide NIR emission by the proper combination between the cyclometalated ligand and the tetradentate ancillary ligand.

Multisignaling detection of Hg2+ based on a phosphorescent iridium(III) complex

Co-reporter:Qiang Zhao, Shujuan Liu, Fuyou Li, Tao Yi and Chunhui Huang

Dalton Transactions 2008 (Issue 29) pp:3836-3840

Publication Date(Web):13 Jun 2008

DOI:10.1039/B804858D

A multisignaling chemosensor for Hg2+ based on the iridium(III) complex Ir(thq)2(acac) was realized through UV-Vis absorption, phosphorescent emission and electrochemical measurements. Upon addition of Hg2+, an obvious blue-shift in absorption spectra and a strong decrease of emission intensity were measured for Ir(thq)2(acac), which could be observed by the naked eye. Hg2+ is coordinated to Ir(thq)2(acac), forming a 1 : 1 complex. Because Hg2+ is a thiophilic metal ion, the interaction between Hg2+ and the sulfur atom of cyclometalated ligands is responsible for the significant variations in optical and electrochemical signals.

Ground and excited state intramolecular proton transfer controlled intramolecular charge separation and recombination: A new type of charge and proton transfer reaction

Co-reporter:Daobo Nie, Zuqiang Bian, Anchi Yu, Zhuqi Chen, Zhiwei Liu, Chunhui Huang

Chemical Physics 2008 Volume 348(1–3) pp:181-186

Publication Date(Web):2 June 2008

DOI:10.1016/j.chemphys.2008.02.065

Abstract

A novel β-diketone 1-(4-(9-carbazol)phenyl)-3-phenyl-1,3-propanedione (CDBM) has been synthesized. When excited at 380 nm, this molecule shows single fluorescence. However, when excited at 338 nm, it shows dual fluorescence. A Al³⁺ complex Al(CDBM)₃ has been synthesized to investigate the dual fluorescence of CDBM. It is found that this complex shows single fluorescence under all excitation. This result indicated that the dual fluorescence of CDBM may relate to the intramolecular proton transfer reaction. Based on the experimental and theoretical studies of CDBM, N-(4-cyanophenyl)carbazole (CBN) and Al(CDBM)₃, a “ground and excited state intramolecular proton transfer controlled intramolecular charge separation and recombination” mechanism is proposed to explain the unusual excitation-dependent dual fluorescence of CDBM.

Ultrasound Switch and Thermal Self-Repair of Morphology and Surface Wettability in a Cholesterol-Based Self-Assembly System

Co-reporter:Junchen Wu;Tao Yi Dr.;Tianmin Shu;Mengxiao Yu;Zhiguo Zhou;Miao Xu;Yifeng Zhou;Huijun Zhang;Jiantao Han;Fuyou Li Dr.

Angewandte Chemie International Edition 2008 Volume 47( Issue 6) pp:1063-1067

Publication Date(Web):

DOI:10.1002/anie.200703946

Photophysical Properties of Heteroleptic Iridium Complexes Containing Carbazole-Functionalized -Diketonates

Co-reporter:Zhiwei Liu;Daobo Nie;Zuqiang Bian ;Fangfang Chen;Bin Lou;Jiang Bian

ChemPhysChem 2008 Volume 9( Issue 4) pp:634-640

Publication Date(Web):

DOI:10.1002/cphc.200700648

Abstract

Twelve iridium complexes with general formula of Ir(C^N)₂(LX) [C^N represents the cyclometalated ligand, i.e. 2-(2,4-difluorophenyl) pyridine (dfppy), 2-phenylpyridine (ppy), dibenzo{f, h}quinoxaline (DBQ); LX stands for β-diketonate, i.e. acetyl acetonate (acac), 1-(carbazol-9-yl)-5,5-dimethylhexane-2,4-diketonate (CBDK), 1-(carbazol-9-yl)-5,5,6,6,7,7,7-heptafluoroheptane-2,4-diketonate (CHFDK), 1-(N-ethyl-carbazol-3-yl)-4,4,5,5,6,6,6-heptafluorohexane-1,3-diketonate (ECHFDK)] are synthesized, characterized and their photophysical properties are systemically studied. In addition, crystals of Ir(DBQ)₂(CHFDK) and Ir(DBQ)₂(acac) are obtained and characterized by single crystal X-ray diffraction. The choice of these iridium complexes provides an opportunity for tracing the effect of the triplet energy level of ancillary ligands on the photophysical and electrochemical behaviors. Data show that if the triplet energy level of the β-diketonate is higher than that of the Ir(C^N)₂ fragment and there is no superposition on the state density map, strong ³LC or ³MLCT-based phosphorescence can be obtained. Alternatively, if the state density map of the two parts are in superposition, the ³LC or ³MLCT-based transition will be quenched at room temperature. Density functional theory calculations show that these complexes can be divided into two categories. The lowest excited state is mainly determined by C^N but not β-diketonate when the difference between the triplet energy levels of the two parts is large. However, when this difference is very small, the lowest excited state will be determined by both sides. This provides a satisfactory explanation for the experimental observations.

Thermostable succinonitrile-based gel electrolyte for efficient, long-life dye-sensitized solar cells

Co-reporter:Zhigang Chen, Hong Yang, Xianghong Li, Fuyou Li, Tao Yi and Chunhui Huang

Journal of Materials Chemistry A 2007 vol. 17(Issue 16) pp:1602-1607

Publication Date(Web):31 Jan 2007

DOI:10.1039/B615915J

Succinonitrile, a molecular plastic crystal, can be modified to become gel by introducing the hydrogen bond (O–H⋯F) network upon addition of silica nanoparticles and 1-butyl-3-methylimidazolium tetrafluoroborate (BMI·BF4). The succinonitrile–BMI·BF4–silica gel system is thermostable over a wide temperature range. The gel electrolyte based on this system containing I− and I3− is also thermostable and highly conductive (6.6–18.2 mS cm−1) in the measured temperature region (20–80 °C). The appropriate addition of silica nanoparticles and BMI·BF4 has no adverse effects on the mobility capability of I−/I3− ions, and the absence of succinonitrile deteriorates the mobility capability. Importantly, dye-sensitized solar cells (DSSCs) with this gel electrolyte show solar-to-electric energy conversion efficiency of 5.0–5.3% over a wide temperature range (20–80 °C). Furthermore, the aging test reveals that the cell still maintains 93% of its initial value for the conversion efficiency after being stored at 60 °C for 1000 h, indicating an excellent long-time durability.

Hydrogen bonding assisted switchable fluorescence in self-assembled complexes containing diarylethene: controllable fluorescent emission in the solid state

Co-reporter:Shuzhang Xiao, Ying Zou, Juncheng Wu, Yifeng Zhou, Tao Yi, Fuyou Li and Chunhui Huang

Journal of Materials Chemistry A 2007 vol. 17(Issue 24) pp:2483-2489

Publication Date(Web):12 Apr 2007

DOI:10.1039/B701712J

Switchable supramolecular self-assemblies based on the interaction between pyridine group containing diarylethene unit (BTEPy) and carboxylic acids were designed and fabricated in this report. Fluorescent enhancement was observed in all of these assembled systems not only in solution, but also in the solid state as well as in the nanoparticles. A clear red-shift emerged in the solid film of the assembled system with BTEPy as a single fluorophore. Fluorescent photochromic organic nanoparticles were also realized in this system. When BTEPy interacted with a proton donor containing a BODIPY dye, the “concentration quenching” problem in the solid state was alleviated due to the hydrogen bond formation and an energy transfer process, with a 65 nm blue shift of the fluorescence. The solid state fluorescence of all these assemblies was effectively switched by alternating irradiation with UV and visible light. Moreover, with the separate wavelengths of writing, reading and erasing cycles in the BODIPY system, control of the fluorescence intensity in a reversible manner without causing destruction in readout capability was realized. The formation of hydrogen bonds between the pyridine group and carboxylic acids of these components was verified by FT-IR, XPS and 1H NMR.

A photochromic fluorescent switch in an organogel system with non-destructive readout ability

Co-reporter:Shuzhang Xiao, Ying Zou, Mengxiao Yu, Tao Yi, Yifeng Zhou, Fuyou Li and Chunhui Huang

Chemical Communications 2007 (Issue 45) pp:4758-4760

Publication Date(Web):31 Aug 2007

DOI:10.1039/B709409D

A fluorescent organogel based on photochromic dithienylethene was obtained, whose optimal excitation wavelength (470 nm) results in little structural change of both open and closed isomers of diarylethene, thus presenting the first example of a fluorescent switch with non-destructive readout ability in the gel state.

Nanocrystalline TiO2 film with textural channels: Exhibiting enhanced performance in quasi-solid/solid-state dye-sensitized solar cells

Co-reporter:Zhigang Chen, Yiwen Tang, Hong Yang, Yongyao Xia, Fuyou Li, Tao Yi, Chunhui Huang

Journal of Power Sources 2007 Volume 171(Issue 2) pp:990-998

Publication Date(Web):27 September 2007

DOI:10.1016/j.jpowsour.2007.07.007

Novel nanocrystalline TiO2 films with the textural channels are obtained for dye-sensitized solar cells (DSSCs). The textural channels consisting of the cracks on the surface and the nanopores with average diameter of about 41 nm are produced by packaging ZnO nanowires with diameter of 30–50 nm into TiO2 films and subsequently etching ZnO nanowires by hydrochloric acid. The performances of DSSCs based on novel TiO2 films (with the textural channels) and traditional TiO2 films (without the textural channels) are investigated, respectively. When two kinds of typical quasi-solid-state electrolytes and one kind of solid-state electrolyte are used, the energy conversion efficiencies of DSSCs from novel TiO2 films are improved by 20–30% compared to that from traditional TiO2 films. The reasons for the great improvement are investigated chiefly by UV–vis absorption spectra, field emission-scanning electron microscope (FE-SEM) and electrochemical impedance spectroscopy (EIS) technique. The results show that the introduction of the textural channels facilitates better penetration of quasi-solid/solid-state electrolytes into the nanopores of novel TiO2 films and thus results in better interfacial/electrical contact and faster interfacial reaction.

Syntheses and electroluminescent properties of two europium ternary complexes Eu(DBM)3(PBO) and Eu(DBM)3(PBT)

Co-reporter:Min Guan, Lihua Gao, Shanshan Wang, Chunhui Huang, Kezhi Wang

Journal of Luminescence 2007 Volume 127(Issue 2) pp:489-493

Publication Date(Web):December 2007

DOI:10.1016/j.jlumin.2007.02.042

Two europium complexes, Eu(DBM)3(PBO) and Eu(DBM)3(PBT) (DBM=dibenzoylmethanato, PBO=2-(2-pyridyl)benzoxazole, PBT=2-(2-pyridyl)benzothiazole), were prepared and used as emitting materials in organic electroluminescent (EL) devices. The devices with the structures ITO/TPD/Eu(DBM)3(PBO) (or Eu(DBM)3(PBT)/BCP/Alq3/Mg:Ag/Ag emit red light originating from the europium complexes.

Efficient, saturated red electroluminescent devices with modified pyran-containing emitters

Co-reporter:Lifen Yang, Min Guan, Daobo Nie, Bin Lou, Zhiwei Liu, Zuqiang Bian, Jiang Bian, Chunhui Huang

Optical Materials 2007 Volume 29(Issue 12) pp:1672-1679

Publication Date(Web):August 2007

DOI:10.1016/j.optmat.2006.09.013

A series of red dopants, i.e., 4-(dicyanomethylene)-2-methyl-6-(o-methoxy(p-diethylamino))-4H-pyran (A), 4-(dicyanomethylene)-2-methyl-6-(o-ethoxy(p-diethylamino))-4H-pyran (B), 4-(dicyanomethylene)-2-methyl-6-(o-(n-proplyoxy) (p-diethylamino))-4H-pyran (C) and 4-(dicyanomethylene)-2-methyl-6-(o-(n-butoxy) (p-diethylamino))-4H-pyran (D) for application in organic light-emitting diodes (OLEDs) have been synthesized and characterized. It was found that by introducing a (diethylamino)-2-alkoxy segment as electron donor and 4-(dicyanomethylene)-2-methyl-4H-pyran moiety as electron acceptor to form the molecular skeleton, the resultant emitters have high photoluminescent quantum yields and saturated red emissions. OLEDs devices based on the present emitters at varying doping levels have been fabricated. Devices using the new emitters as the dopant at about 1 wt% doping levels show excellent performances. The luminance of them can achieve 8785–12540 cd/m2 with the highest luminous efficiency around 2.0 lm/W.

Photochromic Organoboron-Based Dithienylcyclopentene Modulated by Fluoride and Mercuric(II) Ions

Co-reporter:Hong Yang Dr.;Mei Shi Dr.;Zhiguo Zhou Dr.;Fuyou Li ;Tao Yi ;Shuzhang Xiao Dr.

ChemPhysChem 2007 Volume 8(Issue 9) pp:1289-1292

Publication Date(Web):10 MAY 2007

DOI:10.1002/cphc.200600723

Photochromic process: Organoboron-functionalized 1,2-dithienylcyclopentene shows photochromism. Its absorption spectra can be modulated by fluoride and mercuric ions. The maximum of the photostationary state shifts from 560 to 490 nm upon the addition of fluoride anions and to 450 nm upon the addition of mercuric cations. The modulation mechanism is investigated.

A Thermostable and Long-Term-Stable Ionic-Liquid-Based Gel Electrolyte for Efficient Dye-Sensitized Solar Cells

Co-reporter:Zhigang Chen Dr.;Tao Yi ;Hong Yang Dr.;Fuyou Li

ChemPhysChem 2007 Volume 8(Issue 9) pp:1293-1297

Publication Date(Web):10 MAY 2007

DOI:10.1002/cphc.200700116

Binary ionic liquids are used to prepare two thermostable and highly conductive gel electrolytes (A and B). Quasi-solid-state dye-sensitized solar cells using these electrolytes show high power conversion efficiencies of up to 5.8 % at 20 °C and work well over a wide temperature range (20–80 °C), as shown by plots of photocurrent density versus voltage (see picture), and remain in the gel state even at 80 °C (inset).

Red Phosphorescent Iridium Complex Containing Carbazole-Functionalized β-Diketonate for Highly Efficient Nondoped Organic Light-Emitting Diodes

Co-reporter:Z. W. Liu;M. Guan;Z. Q. Bian;D. B. Nie;Z. L. Gong;Z. B. Li;C. H. Huang

Advanced Functional Materials 2006 Volume 16(Issue 11) pp:

Publication Date(Web):23 JUN 2006

DOI:10.1002/adfm.200600099

A novel red phosphorescent iridium complex containing a carbazole-functionalized β-diketonate, Ir(DBQ)₂(CBDK) (bis(dibenzo[f,h]quinoxalinato-N,C²) iridium (1-(carbazol-9-yl)-5,5-dimethylhexane-2,4-diketonate)) is designed, synthesized, and characterized. The electrophosphorescence properties of a nondoped device using the title complex as an emitter with a device configuration of indium tin oxide (ITO)/N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-diphenyl-4,4′-diamine (NPB; 20 nm)/iridium complex (20 nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP; 5 nm)/tris(8-hydroxyquinoline) (AlQ; 30 nm)/Mg_0.9Ag_0.1 (200 nm)/Ag (80 nm) are examined. The results show that the nondoped device achieves a maximum lumen efficiency as high as 3.49 lm W^–1. To understand this excellent result observed, two reference complexes Ir(DBQ)₂(acac), where acac is the acetyl acetonate anion, and Ir(DBQ)₂(FBDK), [bis(dibenzo[f,h]quinoxalinato-N,C²) iridium (1-(9-methyl-fluoren-9-yl)-6,6-dimethylheptane-3,5-diketonate)], have also been synthesized, and as emitters they were examined under the same device configuration. The maximum lumen efficiency of the former compound is found to be 0.26 lm W^–1 while that for the latter is 0.37 lm W^–1, suggesting that the excellent performance of Ir(DBQ)₂(CBDK) can be attributed mainly to an improved hole-transporting property that benefits the exciton transport. In addition, a bulky diketonate group separates the emitter centers from each other, which is also important for organic light-emitting diodes.

Promoting near-infrared emission of neodymium complexes by tuning the singlet and triplet energy levels of β-diketonates

Co-reporter:Lifen Yang, Zeliang Gong, Daobo Nie, Bin Lou, Zuqiang Bian, Min Guan, Chunhui Huang, Hyun Joo Lee and Woo Phil Baik

New Journal of Chemistry 2006 vol. 30(Issue 5) pp:791-796

Publication Date(Web):28 Mar 2006

DOI:10.1039/B601160H

A series of neodymium complexes with various modified β-diketonates and their corresponding gadolinium complexes have been synthesized and characterized. The singlet and triplet energy levels of the coordinated ligands were measured and compared. These complexes emit characteristic Nd3+ light at about 880, 1060, 1330 nm with long-lived lifetimes. The relationship between the structure and photophysical properties has been discussed and the energy transfer process in these complexes has been studied.

Multifunctional photoelectrochemical logic gates based on a hemicyanine sensitized semiconductor electrode

Co-reporter:Fuyou Li, Mei Shi, Chunhui Huang and Linpei Jin

Journal of Materials Chemistry A 2005 vol. 15(Issue 29) pp:3015-3020

Publication Date(Web):13 Jun 2005

DOI:10.1039/B502692J

A new amphiphilic hemicyanine dye, (E)-1,3,3-trimethyl-2-[2-(4-N-methyl-N-hexadecylaminophenyl)ethenyl]indolinium iodide (MHID) has been synthesized and successfully transferred onto a semiconducting transparent indium-tin oxide (ITO) electrode by Langmuir–Blodgett (LB) techniques. The photoelectric conversion properties of the dye MHID monolayer fabricated ITO electrode have been investigated in a three electrode photoelectrochemical cell. The observed photocurrent strongly depends on the applied electrode potential and the concentrations of the electron acceptors and donors. By using electron acceptors and (or) donors as input and photocurrent as output, respectively, we have fabricated this artificial photoelectrochemical system as multifunctional logic gates, corresponding to a series of logic operations (YES, OR, XOR and INHIBIT). Importantly, the gates of this photoelectrochemical system have been interconnected to demonstrate computation as a half-subtractor, with Eu3+ and hydroquinone (H2Q) as the two inputs and the cathodic photocurrent and the absolute value of the photocurrent as the two outputs, respectively.

Highly crystallized mesoporous TiO2 films and their applications in dye sensitized solar cells

Co-reporter:Kun Hou, Bozhi Tian, Fuyou Li, Zuqiang Bian, Dongyuan Zhao and Chunhui Huang

Journal of Materials Chemistry A 2005 vol. 15(Issue 24) pp:2414-2420

Publication Date(Web):13 May 2005

DOI:10.1039/B417465H

By employing mixed inorganic precursors and finely tuning the ageing conditions, crack-free surfactant-templated mesoporous titania films of thickness up to 4 µm have been obtained efficiently. Low angle XRD and TEM show that the mesostructure of the multilayered films was maintained when calcined at the developed temperature of 350 °C, but those films developed crystallinity. A novel type of mesoporous structure featuring highly crystallized anatase framework was produced by a two-step sintering process. Dye sensitized solar cells (DSSCs) were fabricated from these films. The short circuit photocurrent (Isc), open circuit voltage (Voc), and thus the performance of the cell was greatly enhanced when adopting a two-step sintering process, confirming that high crystallinity of the TiO2 electrode is required for high efficiency conversion.

Multisignaling detection of Hg2+ based on a phosphorescent iridium(III) complex

Co-reporter:Qiang Zhao, Shujuan Liu, Fuyou Li, Tao Yi and Chunhui Huang

Dalton Transactions 2008(Issue 29) pp:NaN3840-3840

Publication Date(Web):2008/06/13

DOI:10.1039/B804858D

A multisignaling chemosensor for Hg2+ based on the iridium(III) complex Ir(thq)2(acac) was realized through UV-Vis absorption, phosphorescent emission and electrochemical measurements. Upon addition of Hg2+, an obvious blue-shift in absorption spectra and a strong decrease of emission intensity were measured for Ir(thq)2(acac), which could be observed by the naked eye. Hg2+ is coordinated to Ir(thq)2(acac), forming a 1 : 1 complex. Because Hg2+ is a thiophilic metal ion, the interaction between Hg2+ and the sulfur atom of cyclometalated ligands is responsible for the significant variations in optical and electrochemical signals.

Hydrogen bonding assisted switchable fluorescence in self-assembled complexes containing diarylethene: controllable fluorescent emission in the solid state

Co-reporter:Shuzhang Xiao, Ying Zou, Juncheng Wu, Yifeng Zhou, Tao Yi, Fuyou Li and Chunhui Huang

Journal of Materials Chemistry A 2007 - vol. 17(Issue 24) pp:NaN2489-2489

Publication Date(Web):2007/04/12

DOI:10.1039/B701712J

Switchable supramolecular self-assemblies based on the interaction between pyridine group containing diarylethene unit (BTEPy) and carboxylic acids were designed and fabricated in this report. Fluorescent enhancement was observed in all of these assembled systems not only in solution, but also in the solid state as well as in the nanoparticles. A clear red-shift emerged in the solid film of the assembled system with BTEPy as a single fluorophore. Fluorescent photochromic organic nanoparticles were also realized in this system. When BTEPy interacted with a proton donor containing a BODIPY dye, the “concentration quenching” problem in the solid state was alleviated due to the hydrogen bond formation and an energy transfer process, with a 65 nm blue shift of the fluorescence. The solid state fluorescence of all these assemblies was effectively switched by alternating irradiation with UV and visible light. Moreover, with the separate wavelengths of writing, reading and erasing cycles in the BODIPY system, control of the fluorescence intensity in a reversible manner without causing destruction in readout capability was realized. The formation of hydrogen bonds between the pyridine group and carboxylic acids of these components was verified by FT-IR, XPS and 1H NMR.

Thermostable succinonitrile-based gel electrolyte for efficient, long-life dye-sensitized solar cells

Co-reporter:Zhigang Chen, Hong Yang, Xianghong Li, Fuyou Li, Tao Yi and Chunhui Huang

Journal of Materials Chemistry A 2007 - vol. 17(Issue 16) pp:NaN1607-1607

Publication Date(Web):2007/01/31

DOI:10.1039/B615915J

Succinonitrile, a molecular plastic crystal, can be modified to become gel by introducing the hydrogen bond (O–H⋯F) network upon addition of silica nanoparticles and 1-butyl-3-methylimidazolium tetrafluoroborate (BMI·BF4). The succinonitrile–BMI·BF4–silica gel system is thermostable over a wide temperature range. The gel electrolyte based on this system containing I− and I3− is also thermostable and highly conductive (6.6–18.2 mS cm−1) in the measured temperature region (20–80 °C). The appropriate addition of silica nanoparticles and BMI·BF4 has no adverse effects on the mobility capability of I−/I3− ions, and the absence of succinonitrile deteriorates the mobility capability. Importantly, dye-sensitized solar cells (DSSCs) with this gel electrolyte show solar-to-electric energy conversion efficiency of 5.0–5.3% over a wide temperature range (20–80 °C). Furthermore, the aging test reveals that the cell still maintains 93% of its initial value for the conversion efficiency after being stored at 60 °C for 1000 h, indicating an excellent long-time durability.

Sensitised near-infrared emission from lanthanides using an iridium complex as a ligand in heteronuclear Ir2Ln arrays

Co-reporter:Fang-Fang Chen, Zu-Qiang Bian, Bin Lou , En Ma, Zhi-Wei Liu, Dao-Bo Nie, Zhu-Qi Chen, Jiang Bian, Zhong-Ning Chen and Chun-Hui Huang

Dalton Transactions 2008(Issue 41) pp:NaN5583-5583

Publication Date(Web):2008/09/09

DOI:10.1039/B810016K

The iridium(III) complex Ir(ppy)2(phen5f) [ppy = 2-phenylpyridinato-N,C2′, and phen5f = 4,4,5,5,5-pentafluoro-1-(1′,10′-phenanthrolin-2′-yl)-pentane-1,3-dionate] has been synthesised and used as “complex ligands” to make heteronuclear d–f complexes by the attachment of Ln(NO3)3·xH2O at the vacant coordination sites in the bridging ligand phen5f. The microanalyses and crystal structure characteristics confirmed the formation of the heteronuclear Ir2Ln arrays. The measurement of the lowest triplet state energy level of Ir(ppy)2(phen5f) indicates that it is suitable for the NIR (near-infrared) lanthanide ions, NdIII, YbIIIand ErIII. Upon irradiation of the MLCT (metal-to-ligand charge transfer) absorption of Ir(ppy)2(phen5f) at an excitation wavelength from 380–490 nm, the characteristic emission spectra of the three Ir2Ln arrays (Ln = Nd, Yb, Er) in both the solid state and in CH3CN solution were measured. According to the results, more IrIII complexes will be designed for lanthanide NIR emission by the proper combination between the cyclometalated ligand and the tetradentate ancillary ligand.

A photochromic fluorescent switch in an organogel system with non-destructive readout ability

Co-reporter:Shuzhang Xiao, Ying Zou, Mengxiao Yu, Tao Yi, Yifeng Zhou, Fuyou Li and Chunhui Huang

Chemical Communications 2007(Issue 45) pp:NaN4760-4760

Publication Date(Web):2007/08/31

DOI:10.1039/B709409D

A fluorescent organogel based on photochromic dithienylethene was obtained, whose optimal excitation wavelength (470 nm) results in little structural change of both open and closed isomers of diarylethene, thus presenting the first example of a fluorescent switch with non-destructive readout ability in the gel state.

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