White polymer light-emitting devices (WPLEDs) have become a field of immense interest in both scientific and industrial communities. They have unique advantages such as low cost, light weight, ease of device fabrication, and large area manufacturing. Applications of WPLEDs for solid-state lighting are of special interest because about 20% of the generated electricity on the earth is consumed by lighting. To date, incandescent light bulbs (with a typical power efficiency of 12–17 lm W⁻¹) and fluorescent lamps (about 40–70 lm W⁻¹) are the most widely used lighting sources. However, incandescent light bulbs convert 90% of their consumed power into heat while fluorescent lamps contain a small but significant amount of toxic mercury in the tube, which complicates an environmentally friendly disposal. Remarkably, the device performances of WPLEDs have recently been demonstrated to be as efficient as those of fluorescent lamps.

Here, we summarize the recent advances in WPLEDs with special attention paid to the design of novel luminescent dopants and device structures. Such advancements minimize the gap (for both efficiency and stability) from other lighting sources such as fluorescent lamps, light-emitting diodes based on inorganic semiconductors, and vacuum-deposited small-molecular devices, thus rendering WPLEDs equally competitive as these counterparts currently in use for illumination purposes.

Hard ferromagnetic (L1₀ phase) FePt alloy nanoparticles (NPs) with extremely high magnetocrystalline anisotropy are considered to be one of the most promising candidates for the next generation of ultrahigh-density data storage system. The question of how to generate ordered patterns of L1₀-FePt NPs and how to transform the technology for practical applications represents a key current challenge. Here the direct synthesis of L1₀ phase FePt NPs by pyrolysis of Fe-containing and Pt-containing metallopolymer blend without post-annealing treatment is reported. Rapid single-step fabrication of large-area nanodot arrays (periodicity of 500 nm) of L1₀-ordered FePt NPs can also be achieved by employing the metallopolymer blend, which possesses excellent solubility in most organic solvents and good solution processability, as the precursor through nanoimprint lithography (NIL). Magnetic force microscopy (MFM) imaging of the nanodot pattern indicates that the patterned L1₀ phase FePt NPs are capable of exhibiting decent magnetic response, which suggests a great potential to be utilized directly in the fabrication of bit patterned media (BPM) for the next generation of magnetic recording technology.

New ruthenium(II) photosensitizers [Ru(dcbpy)(L)(NCS)₂] (dcbpy = 4,4′-dicarboxylic acid-2,2′-bipyridine; L = 4,4′-bis{di[4-(N,N′-dimethylamino)phenyl]amino}-2,2′-bipyridine (1), 4,4′-bis[di(4-methoxyphenyl)amino]-2,2′-bipyridine (2), and 4,4′-bis[di(4-tolyl)amino]-2,2′-bipyridine (3)) were prepared and characterized and their application in dye-sensitized solar cells is presented. The optical absorption of these photosensitizers gives a peak at around 540 nm, which is very similar to that of the standard N719. The maximum incident photon-to-current conversion efficiency (IPCE) of 80.6 % was obtained for 3, which corresponded to a power conversion efficiency (η) of 5.68 % under standard air mass (AM) 1.5 sunlight (versus N719 at 6.76 %). Molecular cosensitization of 3 with an organic dye, QS-DPP-I, yielded higher η values up to 6 % relative to the cells based on individual photosensitizers, and the corresponding IPCE can reach 93.6 % at 549 nm. A preliminary stability test of the devices was also conducted.

New heteroleptic cyclometalated iridium(III) 2-phenylpyridine-type complexes with trifluoromethyl substituents and various main-group moieties were synthesized and their photophysical, electrochemical, and electroluminescent (EL) properties studied. The emission color can be tuned by a facile derivatization of the phenyl moiety of 2-phenylpyridine with various main-group moieties, and we have prepared new yellowishgreen to orange triplet emitters with enhanced charge injection/charge transporting features, which can furnish attractive EL performance in phosphorescent organic light-emitting devices (OLEDs). Attempts were also made to fabricate two-color white-light OLEDs based on a combination of fluorescent blue and phosphorescent orange emitters.

A series of simple phenothiazine-based dyes, namely, TP, EP, TTP, ETP, and EEP have been developed, in which the thiophene (T), ethylenedioxythiophene (E), their dimers, and mixtures are present to modulate dye aggregation, charge recombination, and dye regeneration for highly efficient dye-sensitized solar cell (DSSC) applications. Devices sensitized by the dyes TP and TTP display high power conversion efficiencies (PCEs) of 8.07 (J_sc=15.2 mA cm⁻², V_oc=0.783 V, fill factor (FF)=0.679) and 7.87 % (J_sc=16.1 mA cm⁻², V_oc=0.717 V, FF=0.681), respectively; these were measured under simulated AM 1.5 sunlight in conjunction with the I⁻/I₃⁻ redox couple. By replacing the T group with the E unit, EP-based DSSCs had a slightly lower PCE of 7.98 % with a higher short-circuit photocurrent (J_sc) of 16.7 mA cm⁻². The dye ETP, with a mixture of E and T, had an even lower PCE of 5.62 %. Specifically, the cell based on the dye EEP, with a dimer of E, had inferior J_sc and V_oc values and corresponded to the lowest PCE of 2.24 %. The results indicate that the photovoltaic performance can be finely modulated through structural engineering of the dyes. The selection of T analogues as donors can not only modulate light absorption and energy levels, but also have an impact on dye aggregation and interfacial charge recombination of electrons at the interface of titania, electrolytes, and/or oxidized dye molecules; this was demonstrated through DFT calculations, electrochemical impedance analysis, and transient photovoltage studies.

Tris(cyclometalated) iridium(III) phosphorescent emitters with 2-phenylthiazole-type ligands have been designed and synthesized. Their photophysical properties, electrochemical behavior and electroluminescent (EL) performance can be influenced by introducing fluorine atoms to the phenyl moiety of the thiazole-based ligands. The phosphorescent emission maxima can be shifted from 546 nm to 517 nm by increasing the number of the fluorine atoms attached to the ligands of the iridium(III) complexes. Furthermore, the HOMO levels for these phosphorescent complexes exhibit a gradual decrease from –5.28 eV to –5.59 eV with the introduction of fluorine atoms. Owing to the character of their electronic structures, the phosphorescent emitters are preferentially excited by means of a host-guest energy-transfer process in the organic light-emitting diodes (OLEDs). Accordingly, their EL performance is strictly restricted by the triplet energy level difference between the phosphorescent dopant and the host materials. The thiazole-based cyclometalated iridium(III) triplet emitters can exhibit maximum EL efficiencies with η_ext = 7.87 %, η_L = 23.62 cd A^–1 and η_p = 13.46 lm W^–1.

Based on a donor–acceptor framework, several conjugates have been designed and prepared in which an electron-donor moiety, ytterbium(III) porphyrinate (YbPor), was linked through an ethynyl bridge to an electron-acceptor moiety, boron dipyrromethene (BODIPY). Photoluminescence studies demonstrated efficient energy transfer from the BODIPY moiety to the YbPor counterpart. When conjugated with the YbPor moiety, the BODIPY moiety served as an antenna to harvest the lower-energy visible light, subsequently transferring its energy to the YbPor counterpart, and, consequently, sensitizing the Yb^III emission in the near-infrared (NIR) region with a quantum efficiency of up to 0.73 % and a lifetime of around 40 μs. Moreover, these conjugates exhibited large two-photon-absorption cross-sections that ranged from 1048–2226 GM and strong two-photon-induced NIR emission.

A new series of conjugated oligothiophene-bridged bis(arylene ethynylene) small molecules have been designed, synthesized, and characterized by photophysical, electrochemical and computational methods. These compounds were found to have optimal LUMO levels that ensure effective charge transfer from these compounds to [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₀BM). They were utilized as good electron-donor materials that can be blended with electron-acceptor PC₇₀BM in the fabrication of solution-processed molecular bulk heterojunction (BHJ) solar cells. All of these BHJ devices showed very high open-circuit voltage (V_oc) of 0.90–0.97 V, and the best power conversion efficiency achieved was 3.68 %. The high V_oc is consistent with the deeper low-lying HOMO level and is relatively insensitive to the donor : acceptor blend ratio. The spin-coated thin films of these small molecules showed p-channel field-effect charge transport with the hole mobilities of up to 2.04×10⁻⁴ cm² V⁻¹ s⁻¹. These compounds illuminate the potential of solution-processible small-molecular aryl acetylide compounds for efficient power generation in photovoltaic implementation.

In the past few years, squaraine dyes have received increasing attention as a sensitizer for application in dye-sensitized solar cells. This class of dyes not only leaves open a good opportunity to afford conventional high performance dyes but also holds great promise for applications in transparent solar cells due to its low absorption intensity in the eye-sensitive region. This review provides a summary of the developments on squaraine dyes in the field of dye-sensitized solar cells and the opportunities used to improve their overall energy conversion efficiency. In particular, the main factors responsible for the low values of open-circuit voltage, short-circuit photocurrent and fill factor are discussed in detail. Future directions in research and development of near-infrared (NIR) organic materials and their applications are proposed from a personal perspective.

Two novel covalently-linked organic-inorganic hybrid compounds [(n-C₄H₉)₄N]₂[Mo₆O₁₈{≡N–(2-Np)}] (NA–Mo6) and [(n-C₄H₉)₄N]₂[Mo₆O₁₇{≡N–(1-Np)}₂] (NA2–Mo6) (2-Np = 2-naphthyl; 1-Np = 1-naphthyl) have been prepared by the reaction of 2-naphthylamine (2-NpNH₂) or 1-naphthylamine (1-NpNH₂) with [(n-C₄H₉)₄N]₂[Mo₆O₁₉] (Mo6) in the presence of N,N′-dicyclohexylcarbodiimide (DCC) in anhydrous acetonitrile, and have been characterized by ¹H NMR, IR, UV/Vis, and fluorescence spectra as well as X-ray crystallography. Structural analyses reveal the formation of self-assembled infinite 1-D and 3-D supramolecular frameworks. The UV/Vis spectra of NA–Mo6 and NA2–Mo6 show that the lowest energy electronic transfers occur at 362 and 394 nm, respectively, which are dramatically red-shifted when compared to that of Mo6. The luminescence studies show that Mo6 can notably quench the emission of naphthylamine. Monolayer and multilayer films of NA–Mo6 and NA2–Mo6 were fabricated on different substrates by the Langmuir–Blodgett (LB) technique using H₂O as the subphase. For comparison, another two types of organic-inorganic hybrid films composed of noncovalently-linked 1-NpNH₂/Mo6 and 2-NpNH₂/Mo6 systems were also deposited onto the same substrates under the same conditions by the LB technique using an aqueous solution of Mo6 as the subphase. The as-prepared organic-inorganic hybrid films were characterized by π-A isotherms, UV/Vis absorption spectra, photoluminescence spectra, and scanning tunneling microscopy. The results indicate that stable monolayers can be formed at the air–water interface for NA–Mo6 and NA2–Mo6, and at the air–Mo6 solution interface for 1-NpNH₂ and 2-NpNH₂. The four LB films containing NA–Mo6, NA2–Mo6, 1-NpNH₂/Mo6, and 2-NpNH₂/Mo6 display interesting electrical conductivity.

We have studied the properties of organic and organometallic polymers based on a similar chemical structure to elucidate the influence of the metal center on the optical and electronic properties of the polymers as well as their photovoltaic performance. Detailed characterization of the optical properties of both polymers is performed and film morphology and photovoltaic performance are compared. Metal-containing polymers exhibit red-shifted absorption and under optimal processing conditions exhibit different film morphology compared with the metal-free ones. Our results indicate that organometallic polymers represent a promising class of compounds for improved performance in photovoltaic cells.

A new way has been investigated for tuning the optical and electronic performance of cyclometalated iridium(III) phosphors by simple tailoring of the phenyl ring of ppy (Hppy = 2-phenylpyridine) with various main group moieties in [Ir(ppy-X)₂(acac)] (X = POPh₂, SO₂Ph, GePh₃, OPh, OPh(CF₃)₃, SOPh). The geometric and electronic structures of the complexes in the ground state are studied with time-dependent density functional theory (TD-DFT) and Hartree–Fock method, whereas the lowest singlet and triplet excited states are optimized by the configuration interaction singles method. At the TD-DFT level, absorptions and phosphorescence properties of the studied molecules were calculated on the basis of the optimized ground- and excited-state geometries, respectively. The various main group moieties produce a remarkable influence on their optoelectronic properties. The calculated data reveal that the studied molecules have improved charge transfer rate and balance and can be used as hole and electron transport materials in organic light-emitting devices. In particular, the work can provide valuable insight toward future design of new and relatively rare luminescent materials with enhanced electron-injection and electron-transporting features. Copyright © 2012 John Wiley & Sons, Ltd.

An elaborated theoretical investigation on the optical and electronic properties of three fluorene-based platinum(II) and iridium(III) cyclometalated complexes Pt-a, Ir-a and Ir-b is reported. The geometric and electronic structures of the complexes in the ground state are studied with density functional theory and Hartree Fock approaches, while the lowest triplet excited states are optimized by singles configuration interaction (CIS) methods. At the time-dependent density functional theory (TD-DFT) level, molecular absorption and emission properties were calculated on the basis of optimized ground- and excited-state geometries, respectively. The computational results show that the appearance of triphenylamino (TPA) moiety at the 9-position of fluorene ring favors the hole-creation and leads to red-shifts of absorption and emission spectra. Moreover, Pt-a and Ir-b are nice hole-transporting materials whereas Ir-a has good charge-transfer balance, which render them useful for the realization of efficient OLEDs (Organic Light-Emitting Diodes).

In the synthesis of binuclear organobismuth complexes (1–6) through treatment of organobismuth chlorides with NaOH or Na₂S⋅9H₂O, the two 5,6,7,12-tetrahydrodibenz [c,f][1,5]azabismocine frameworks are cross-linked by either a sulfur or an oxygen atom. The complexes (1–6) show high catalytic efficiency in the synthesis of cyclic carbonates from 2-(chloromethyl)oxirane and CO₂. Compared with their precursor chlorides (7–9), methoxide 10 and methanethioate 11 which are mononuclear organobismuth complexes, the binuclear organobismuth complexes show higher cooperative catalytic effect. However, the complexes with an oxygen bridge (1–3) are not stable in air and lose their catalytic efficiency because of hydrolysis or CO₂ adsorption (forming organobismuth carbonates in the latter case). Nonetheless, the binuclear organobismuth complexes (4–6) with a sulfur bridge are highly stable in air and can be applied in the synthesis of cyclic carbonates (with the co-presence of Bu₄NI) across various kinds of epoxides, thus exhibiting satisfactory efficiency and selectivity.

Four new solution-processible small-molecular platinum(II)–bis(aryleneethynylene) complexes consisting of benzothiadiazole as the electron acceptor and triphenylamine and/or thiophene as the electron donor were conveniently synthesized and characterized by physicochemical and computational methods, and utilized as the electron-donor materials in the fabrication of solution-processed bulk heterojunction (BHJ) solar cells. The effect of different electron-donor groups in these small molecules on the optoelectronic and photovoltaic properties was also examined. The optical and time-dependent density functional theory studies showed that the incorporation of stronger electron-donor groups significantly enhanced the solar-absorption abilities of the complexes. These molecular complexes can serve as good electron donors for fabricating BHJ devices by blending them with the [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₀BM) as the electron acceptor. The best power conversion efficiency of 2.37 % was achieved with the open-circuit voltage of 0.83 V, short-circuit current density of 7.10 mA cm⁻² and fill factor of 0.40 under illumination of an AM 1.5 solar-cell simulator. The spin-coated thin films showed p-channel field-effect charge transport with hole mobilities of up to 2.4×10⁻⁴ cm² V⁻¹ s⁻¹ for these molecules. The present work illuminates the potential of well-defined organometallic complexes in developing light-harvesting small molecules for efficient power generation in organic photovoltaics implementation.

A novel yellowish-green triplet emitter, bis(5-(trifluoromethyl)-2-p-tolylpyridine) (acetylacetonate)iridium(III) (1), was conveniently synthesized and used in the fabrication of both monochromatic and white organic light-emitting diodes (WOLEDs). At the optimal doping concentration, monochromatic devices based on 1 exhibit a high efficiency of 63 cd A⁻¹ (16.3% and 36.6 lm W⁻¹) at a luminance of 100 cd m⁻². By combining 1 with a phosphorescent sky-blue emitter, bis(3,5-difluoro-2-(2-pyridyl)phenyl)-(2-carboxypyridyl)iridium(III) (FIrPic), and a red emitter, bis(2-benzo[b]thiophen-2-yl-pyridine)(acetylacetonate)iridium(III) (Ir(btp)₂(acac)), the resulting electrophosphorescent WOLEDs show three evenly separated main peaks and give a high efficiency of 34.2 cd A⁻¹ (13.2% and 18.5 lm W⁻¹) at a luminance of 100 cd m⁻². When 1 is mixed with a deep-blue fluorescent emitter, 4,4′-bis(9-ethyl-3-carbazovinylene)-1,1′-biphenyl (BCzVBi), and Ir(btp)₂(acac), the resulting hybrid WOLEDs demonstrate a high color-rendering index of 91.2 and CIE coordinates of (0.32, 0.34). The efficient and highly color-pure WOLEDs based on 1 with evenly separated red, green, blue peaks and a high color-rendering index outperform those of the state-of-the-art emitter, fac-tris(2-phenylpyridine)iridium(III) (Ir(ppy)₃), and are ideal candidates for display and lighting applications.

A series of gadolinium(III) porphyrinate complexes was synthesized in moderate yield from the interaction of meso-substituted porphyrin free bases with Ln[N(SiMe₃)₂]₃·x[LiCl(THF)₃], followed by the addition of a tripodal anion L_OMe^– – an effective encapsulating agent for lanthanide ions. These new complexes were fully characterized by X-ray crystallography, elemental analysis, mass spectrometry, and infrared spectroscopy. The electronic spectra show a near-infrared phosphorescence from the triplet state of the porphyrin rings and exhibit a very characteristic vibronic-structured emission.

A series of cationic lanthanide porphyrinate complexes of the general formula [(Por)Ln(H₂O)₃]⁺ (Ln³⁺=Yb³⁺ and Er³⁺) were synthesized in moderate yields through the interaction of meso-pyridyl-substituted porphyrin free bases (H₂Por) with [Ln{N(SiMe₃)₂}₃]⋅x [LiCl(thf)₃], and the corresponding neutral derivatives [(Por)Ln(L_OMe)] (L_OMe⁻=[(η⁵-C₅H₅)Co{P(O)(OMe)₂}₃]⁻) were also prepared from [(Por)Ln(H₂O)₃]⁺ by the addition of the tripodal anion, L_OMe⁻, an effective encapsulating agent for lanthanide ions. Furthermore, the water-soluble lanthanide(III) porphyrinate complexes—including [(cis-DMPyDPP)Yb(H₂O)₃]Cl₃ (cis-DMPyDPP=5,10-bis(N-methylpyridinium-4′-y1)-15,20-di(phenyl)porphyrin), [(trans-DMPyDPP)Yb(H₂O)₃]Cl₃ (trans-DMPyDPP=5,15-bis(N-methylpyridinium-4′-y1)-10,20-di(phenyl)porphyrin), [(TMPyP)Yb(L_OMe)]I₄, and [(TMPyP)Er(L_OMe)]I₄ (TMPyP=tetrakis(N-methylpyridinium-4-y1)porphyrin)—were obtained by methylation of the corresponding complexes with methyl iodide and unambiguously characterized. The binding interactions and photocleavage activities of the water-soluble lanthanide(III) porphyrinate complexes towards DNA were investigated by UV-visible, fluorescence, and near-infrared luminescence spectroscopy, as well as circular dichroism and gel electrophoresis.

With the aim of endowing triplet emitters in the development of organic light-emitting devices (OLEDs) with electron-injection/-transporting (EI/ET) features, the phenylsulfonyl moiety was introduced into the phenyl ring of a 2-phenylpyridine (Hppy) ligand and the yellow phosphorescent heteroleptic iridium(III) complex 1 was developed. It was shown that the SO₂Ph unit could provide EI/ET character to 1, as indicated from both electrochemical and computational data. Complex 1 is a promising yellow-emitting material for both monochromatic OLEDs and white OLEDs (WOLEDs). The outstanding electronic traits associated with 1, coupled with careful device design, afforded very attractive electroluminescent performances for two-element WOLEDs, including a low turn-on voltage of less than 3.7 V, a maximum brightness of 48 000 cd m⁻², an external quantum efficiency of 13.0 %, a luminance efficiency of 34.7 cd A⁻¹, and a power efficiency of 24.3 Lm W⁻¹. In addition, a good color rendering index (CRI) of about 74, a stable white color with a Commission Internationale de L′Eclairage (CIE_x,y) variation of Δ(x, y)<±(0.02, 0.02), and a correlated color temperature higher than 5130 K were obtained. These encouraging results indicate the potential of these WOLEDs as good candidates for warm indoor lighting sources, as well as the critical contribution of such key EI/ET properties to triplet emitters to advance new OLED research.

A new series of organometallic/inorganic composite Langmuir-Blodgett (LB) films consisting of a rigid-rod polyplatinyne polymer coordinated with 2,7-bis(buta-1,3-diynyl)-9,9-dihexylfluorene (denoted as PtP) as the π-conjugated organometallic molecule, an europium-substituted polyoxometalate (POM; POM = Na₉EuW₁₀O₃₆, K₁₃[Eu(SiW₁₁O₃₉)₂] and K₅[Eu(SiW₁₁O₃₉)(H₂O)₂]) as the inorganic component, and an amphiphilic behenic acid (BA) as the auxiliary film-forming agent were prepared. Structural and photophysical characterization of these LB films were achieved by π–A isotherms, absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low-angle X-ray diffraction. Our experimental results indicate that stable, well-defined, and well-organized Langmuir and LB films are formed in pure water and POM subphases, and the presence of Eu-based POM in the subphase causes an area expansion. It is proposed that a lamellar layered structure exists for the PtP/BA/POM LB film in which the POM and PtP molecules can lay down with the interfacial planes. Luminescence spectra of the prepared hybrid LB films show that near-white emission spectra can be obtained due to the dual-emissive nature of the mixed PtP/POM blends. These Pt-polyyne-based LB films displayed interesting electric conductivity behavior. Among them, PtP/BA/POM 13-layer films showed a good electrical response, with the tunneling current up to ±100 nA when the voltage was monitored between −1 and 7 V. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 879–888, 2010

A homologous set of 9,9-dialkyl-4,5-diazafluorene compounds were prepared by alkylation of 4,5-diazafluorene with the appropriate alkyl bromide and under basic conditions. The structures of these simple organic compounds were confirmed by spectroscopic techniques (FTIR, NMR, and FABMS). Their biological effects toward a panel of human carcinoma cells, including Hep3B hepatocellular carcinoma, MDAMB-231 breast carcinoma, and SKHep-1 hepatoma cells, were investigated; a structure–activity correlation was established with respect to the length of the alkyl chain and the fluorene ring structure. The relationship between the mean potency [log(1/IC₅₀)] and alkyl chain length was systematically studied. The results show that compounds with butyl, hexyl, and octyl chains exhibit good growth inhibitory effects toward these three human carcinoma cell lines, and the 9,9-dihexyl-4,5-diazafluorene further exhibits antitumor activity in athymic nude mice Hep3B xenograft models. For the structurally related dialkylfluorenes that lack the diaza functionality, in vitro cytotoxicity was not observed at clinically relevant concentrations.

Phosphorus-bridged strained [1]ferrocenophanes [Fe{(η-C₅H₄)₂P(CH₂CMe₃)}] (2) and [Fe{(η-C₅H₄)₂P(CH₂SiMe₃)}] (3) with neopentyl and (trimethylsilyl)methyl substituents on phosphorus, respectively, have been synthesized and characterized. Photocontrolled living anionic ring-opening polymerization (ROP) of the known phosphorus-bridged [1]ferrocenophane [Fe{(η-C₅H₄)₂P(CMe₃)}] (1) and the new monomers 2 and 3, initiated by Na[C₅H₅] in THF at 5 °C, yielded well-defined polyferrocenylphosphines (PFPs), [Fe{(η-C₅H₄)₂PR}]_n (R=CMe₃ (4), CH₂CMe₃ (5), and CH₂SiMe₃ (6)), with controlled molecular weights (up to ca. 60×10³ Da) and narrow molecular weight distributions. The PFPs 4–6 were characterized by multinuclear NMR spectroscopy, DSC, and by GPC analysis of the corresponding poly(ferrocenylphosphine sulfides) obtained by sulfurization of the phosphorus(III) centers. The living nature of the photocontrolled anionic ROP allowed the synthesis of well-defined all-organometallic PFP-b-PFS_F (7 a and 7 b) (PFS_F=polyferrocenylmethyl(3,3,3,-trifluoropropyl)silane) diblock copolymers through sequential monomer addition. TEM studies of the thin films of the diblock copolymer 7 b showed microphase separation to form cylindrical PFS_F domains in a PFP matrix.

A new series of symmetric and unsymmetric Pt(II) bis(acetylide) complexes of the type DC≡CPt(PBu₃)₂C≡CD (DPtD), AC≡CPt(PBu₃)₂C≡CA (APtA) and DC≡CPt(PBu₃)₂C≡CA (DPtA) (D, donor groups; A, acceptor groups) are synthesized, and show superior optical power limiting (OPL)/optical transparency trade-offs. By tailoring the electronic properties of the aryleneethynylene group, distinct electronic structures for these metalated complexes can be obtained, which significantly affect their photophysical behavior and OPL properties for a nanosecond laser pulse at 532 nm. Electronic influence of the ligand type and the molecular symmetry of metal group on the optical transparency/nonlinearity optimization is thoroughly elucidated. Generally, aryleneethynylene ligands with π electron-accepting nature will effectively enhance the harvesting efficiency of the triplet excited states. The ligand variation to the OPL strength of these Pt(II) compounds follows the order: DPtD > DPtA > APtA. These results could be attributed to the distinctive excited state character induced by their different electronic structures, on the basis of the data from both photophysical studies and theoretical calculations. All of the complexes show very good optical transparencies in the visible-light region and exhibit excellent OPL responses with very impressive figure of merit σ_ex/σ_o values (up to 17), which remarkably outweigh those of state-of-the-art reverse saturable absorption dyes such as C₆₀ and metallophthalocyanines with very poor transparencies. Their lower optical-limiting thresholds (0.05 J cm⁻² at 92% linear transmittance) compared with that of the best materials (ca. 0.07 J cm⁻² for InPc and PbPc dyes) currently in use will render these highly transparent materials promising candidates for practical OPL devices for the protection of human eyes and other delicate electro-optic sensors.

The synthesis, isomeric studies, and photophysical characterization of a series of multifunctional cyclometalated iridium(III) complexes containing a fluoro- or methyl-substituted 2-[3-(N-phenylcarbazolyl)]pyridine molecular framework are presented. All of the complexes are thermally stable solids and highly efficient electrophosphors. The optical, electrochemical, photo-, and electrophosphorescence traits of these iridium phosphors have been studied in terms of the electronic nature and coordinating site of the aryl or pyridyl ring substituents. The correlation between the functional properties of these phosphors and the results of density functional theory calculations was made. Arising from the propensity of the electron-rich carbazolyl group to facilitate hole injection/transport, the presence of such a moiety can increase the highest-occupied molecular orbital levels and improve the charge balance in the resulting complexes relative to the parent phosphor with 2-phenylpyridine ligands. Remarkably, the excited-state properties can be manipulated through ligand and substituent effects that allow the tuning of phosphorescence energies from bluish green to deep red. Electrophosphorescent organic light-emitting diodes (OLEDs) with outstanding device performance can be fabricated based on these materials, which show a maximum current efficiency of approximately 43.4 cd A⁻¹, corresponding to an external quantum efficiency of approximately 12.9 % ph/el (photons per electron) and a power efficiency of approximately 33.4 Lm W⁻¹ for the best device. The present work provides a new avenue for the rational design of multifunctional iridium–carbazolyl electrophosphors, by synthetically tailoring the carbazolyl pyridine ring that can reveal a superior device performance coupled with good color-tuning versatility, suitable for multicolor-display technology.

The synthesis, structures, photophysics, electrochemistry and electrophosphorescent properties of new red phosphorescent cyclometalated iridium(III) isoquinoline complexes, bearing 9-arylcarbazolyl chromophores, are reported. The functional properties of these red phosphors correlate well with the results of density functional theory calculations. The highest occupied molecular orbital levels of these complexes are raised by the integration of a carbazole unit to the iridium isoquinoline core so that the hole-transporting ability is improved in the resulting complexes relative to those with 1-phenylisoquinoline ligands. All of the complexes are highly thermally stable and emit an intense red light at room temperature with relatively short lifetimes that are beneficial for highly efficient organic light-emitting diodes (OLEDs). Saturated red OLEDs, fabricated using these dyes as the phosphorescent dopants both as vacuum-evaporated and spin-coated emissive layers, have been achieved in a multilayer configuration with outstanding red color purity at Commission International de L'Éclairage (CIE) coordinates of (0.67,0.33) to (0.68,0.32). Some of the devices can show very high efficiencies with a maximum external quantum efficiency of up to 12 % photons per electron. The excellent performance of these red emitters indicates the advantage of the carbazole module in the ligand framework; demonstrated by an improved hole-transporting ability that facilitates exciton transport. These materials could thus provide a new avenue for the rational design of heavy-metal electrophosphors that reveal a superior device efficiency/color purity trade-off necessary for pure red-light generation.

A new and synthetically versatile strategy has been developed for the phosphorescence color tuning of cyclometalated iridium phosphors by simple tailoring of the phenyl ring of ppy (Hppy = 2-phenylpyridine) with various main-group moieties in [Ir(ppy-X)₂(acac)] (X = B(Mes)₂, SiPh₃, GePh₃, NPh₂, POPh₂, OPh, SPh, SO₂Ph). This can be achieved by shifting the charge-transfer character from the pyridyl groups in some traditional iridium ppy-type complexes to the electron-withdrawing main-group moieties and these assignments were supported by theoretical calculations. This new color tuning strategy in Ir^III-based triplet emitters using electron-withdrawing main-group moieties provides access to Ir^III phosphors with improved electron injection/electron transporting features essential for highly efficient, color-switchable organic light-emitting diodes (OLEDs). The present work furnished OLED colors spanning from bluish-green to red (505–609 nm) with high electroluminescence efficiencies which have great potential for application in multicolor displays. The maximum external quantum efficiency of 9.4%, luminance efficiency of 10.3 cd A⁻¹ and power efficiency of 5.0 lm W⁻¹ for the red OLED (X = B(Mes)₂), 11.1%, 35.0 cd A⁻¹, and 26.8 lm W⁻¹ for the bluish-green device (X = OPh), 10.3%, 36.9 cd A⁻¹, and 28.6 lm W⁻¹ for the bright green device (X = NPh₂) as well as 10.7%, 35.1 cd A⁻¹, and 23.1 lm W⁻¹ for the yellow-emitting device (X = SO₂Ph) can be obtained.

By attaching a bulky, inductively electron-withdrawing trifluoromethyl (CF₃) group on the pyridyl ring of the rigid 2-[3- (N-phenylcarbazolyl)]pyridine cyclometalated ligand, we successfully synthesized a new heteroleptic orange-emitting phosphorescent iridium(III) complex [Ir(L₁)₂(acac)] 1 (HL₁ = 5-trifluoromethyl-2-[3-(N-phenylcarbazolyl)]pyridine, Hacac = acetylacetone) in good yield. The structural and electronic properties of 1 were examined by X-ray crystallography and time-dependent DFT calculations. The influence of CF₃ substituents on the optical, electrochemical and electroluminescence (EL) properties of 1 were studied. We note that incorporation of the carbazolyl unit facilitates the hole-transporting ability of the complex, and more importantly, attachment of CF₃ group provides an access to a highly efficient electrophosphor for the fabrication of orange phosphorescent organic light-emitting diodes (OLEDs) with outstanding device performance. These orange OLEDs can produce a maximum current efficiency of ∼40 cd A⁻¹, corresponding to an external quantum efficiency of ∼12% ph/el (photons per electron) and a power efficiency of ∼24 lm W⁻¹. Remarkably, high-performance simple two-element white OLEDs (WOLEDs) with excellent color stability can be fabricated using an orange triplet-harvesting emitter 1 in conjunction with a blue singlet-harvesting emitter. By using such a new system where the host singlet is resonant with the blue fluorophore singlet state and the host triplet is resonant with the orange phosphor triplet level, this white light-emitting structure can achieve peak EL efficiencies of 26.6 cd A⁻¹ and 13.5 lm W⁻¹ that are generally superior to other two-element all-fluorophore or all-phosphor OLED counterparts in terms of both color stability and emission efficiency.

A series of solution-processable and strongly visible-light absorbing polyplatinynes containing oligothienyl–fluorene ring hybrids were synthesized and characterized. These rigid-rod organometallic materials are soluble in polar organic solvents and show intense absorptions in the visible spectral region, rendering them excellent candidates for bulk heterojunction polymer solar cells. The photovoltaic behavior depends significantly on the number of thienyl rings along the polymer chain, and some of these polymer solar cells show high power conversion efficiencies (PCEs) of up to 2.9% and a peak external quantum efficiency to 83% under AM1.5 simulated solar illumination. The effect of oligothienyl chain length on improving the polymer solar cell efficiency and on their optical and charge transport properties is elucidated in detail. At the same blend ratio of 1:5, the light-harvesting capability and PCE increase markedly with increasing number of thienyl rings. The power dependencies of the solar cell parameters (including the short-circuit current density, open-circuit voltage, fill-factor, and PCE) were also examined. The present work opens up an attractive avenue to developing conjugated metallopolymers with broad and strong solar energy absorptions and tunable solar cell efficiency and supports the potential of metalated conjugated polymers for efficient power generation.

With the target to design and develop new functionalized green triplet light emitters that possess distinctive electronic properties for robust and highly efficient phosphorescent organic light-emitting diodes (PHOLEDs), a series of bluish–green to yellow–green phosphorescent tris-cyclometalated homoleptic iridium(III) complexes [Ir(ppy-X)₃] (X=SiPh₃, GePh₃, NPh₂, POPh₂, OPh, SPh, SO₂Ph, Hppy=2-phenylpyridine) have been synthesized and fully characterized by spectroscopic, redox, and photophysical methods. By chemically manipulating the lowest triplet-state character of Ir(ppy)₃ with some functional main-group 14–16 moieties on the phenyl ring of ppy, a new family of metallophosphors with high-emission quantum yields, short triplet-state lifetimes, and good hole-injection/hole-transporting or electron-injection/electron-transporting properties can be obtained. Remarkably, all of these Ir^III complexes show outstanding electrophosphorescent performance in multilayer doped devices that surpass that of the state-of-the-art green-emitting dopant Ir(ppy)₃. The devices described herein can reach the maximum external quantum efficiency (η_ext) of 12.3 %, luminance efficiency (η_L) of 50.8 cd A⁻¹, power efficiency (η_p) of 36.9 Lm W⁻¹ for [Ir(ppy-SiPh₃)₃], 13.9 %, 60.8 cd A⁻¹, 49.1 Lm W⁻¹ for [Ir(ppy-NPh₂)₃], and 10.1 %, 37.6 cd A⁻¹, 26.1 Lm W⁻¹ for [Ir(ppy-SO₂Ph)₃]. These results provide a completely new and effective strategy for carrier injection into the electrophosphor to afford high-performance PHOLEDs suitable for various display applications.

Two series of related donor–acceptor conjugated dipolar, pseudo-quadrupolar (V-shaped) and octupolar molecular systems based on the p-dimesitylborylphenylethynylaniline core, namely, 4-(4-dimesitylborylphenylethynyl)-N,N-dimethylaniline, 4-[4-(4-dimesitylborylphenylethynyl)phenylethynyl]-N,N-dimethylaniline, 3,6-bis(4-dimesitylborylphenylethynyl)-N-n-butylcarbazole and tris[4-(4-dimesitylborylphenylethynyl)phenyl]amine, and on the E-p-dimesitylborylethenylaniline motif, namely, E-4-dimesitylborylethenyl-N,N-di(4-tolyl)aniline, 3,6-bis(E-dimesitylborylethenyl)-N-n-butylcarbazole and tris(E-4-dimesitylborylethenylphenyl)amine have been synthesised by palladium-catalyzed cross-coupling and hydroboration routes, respectively. Their absorption and emission maxima, fluorescence lifetimes and quantum yields have been obtained and their two-photon absorption (TPA) spectra and TPA cross-sections have been examined. Of these systems, the octupolar compound tris(E-4-dimesitylborylethenylphenyl)amine has been shown to exhibit the largest TPA cross-section among the two series of approximately 1000 GM at 740 nm. Its TPA performance is comparable to those of other triphenylamine-based octupoles of similar size. The combination of such large TPA cross-sections and high emission quantum yields, up to 0.94, make these systems attractive for applications involving two-photon excited fluorescence (TPEF).

The synthesis of polymers of the type (-Cz-CC-PtL₂-CC-Cz-X-)_n along with the corresponding model compounds (Ph-PtL′₂-CC-Cz)₂-X-, where Cz=3,3′-carbazole, X=nothing, Cz, or F (2,2′-fluorene), L=PBu₃, and L′=PEt₃ are reported. The electronic spectra (absorption, excitation, emission, and ns-transient spectra) and the photophysics of these species in 2-methyltetrahyrofuran (2MeTHF) at 298 and 77 K are presented. Evidence for singlet electron and triplet energy transfer from the Cz chromophore to the F moiety are provided and discussed in detail. The rate for electron transfer is very fast (>4×10¹¹ s⁻¹), whereas that for triplet–triplet energy transfer is much slower (≈10³ s⁻¹). This work represents a very rare example of studies that address electronic communication in the backbone of a conjugated organometallic polymer.