A new series of bimetallic Cu(I) complexes 1–5 triply bridged by a monoanionic or charge-neutral functionalized 3-(2′-pyridyl)-1,2,4-triazole in a μ–η1(N),η2(N,N) tridentate binding mode and two bis(diphenylphosphino)methane (dppm) ligands have been synthesized. Complexes 1–5 are singly or doubly charged dinuclear Cu(I) species with an eight-membered Cu2C2P4 ring of {Cu(μ-dppm)2Cu} unit, in which 3 and 4 adopt the boat–boat conformation, while 1, 2, and 5 display the chair–boat form. In these dimeric copper(I) complex cations, one of the two Cu(I) ions is four-coordinated, in a highly distorted N2P2 tetrahedral environment and the other is three-coordinated, in a distorted NP2 trigonal planar arrangement. All these Cu(I) complexes exhibit a comparatively weak low-energy absorption in CH2Cl2 solution, ascribed to the charge-transfer transitions with appreciable 1MLCT contribution, as suggested by time-dependent density functional theory (TDDFT) analyses. Complexes 1–5 display good emission properties in both solution and solid states at ambient temperature, which are well-modulated via structural modification of 3-(2′-pyridyl)-1,2,4-triazole, including the alteration of the substituent type (−CF3, −H, −CH3, and −C(CH3)3) and position (ortho-, meta-, and para-position). Furthermore, the variation of the substituent (−CF3 and −C(CH3)3) on the 5-site of the 1,2,4-triazolyl ring markedly influences the proton activity of the 1,2,4-triazolyl-NH, thus leading to the formation of both singly and doubly charged bimetallic Cu(I) species regulated by the NH ↔ N– conversion, resulting from NH deprotonation of the 1,2,4-triazolyl ring.

Three metal-free molecular photosensitizers (S1–S3) featuring a starburst triarylamine donor moiety have been synthesized. They show attractive photocatalytic performance in visible light-driven H2 production from water in their platinized TiO2 composites. A remarkable H2 turnover number (TON) of 10 200 (48 h) was achieved in an S1-anchored system.

L10-ordered FePt nanoparticles (NPs) with ultra-high coercivity were directly prepared from a new metallopolyyne using a one-step pyrolysis method. The chemical ordering, morphology and magnetic properties of the as-synthesized FePt NPs have been studied. Magnetic measurements show the coercivity of these FePt NPs is as high as 3.6 T. Comparison of NPs synthesized under the Ar and Ar/H2 atmospheres shows that the presence of H2 in the annealing environment influences the nucleation and promotes the growth of L10-FePt NPs. Application of this metallopolymer for bit-patterned media was also demonstrated using nanoimprint lithography.

•Novel platinum(II) donor-acceptor (D-A) naphthalene diimide-based copolymers were prepared.•Spectroscopic, thermal, electronic and charge transport properties and structural characterization were carried out.•Organic field-effect transistors using these metallopolyyne polymers were fabricated.Two novel platinum(II) donor-acceptor (D-A) naphthalene diimide (NDI)-based copolymers have been designed and synthesized. The effects of thiophene numbers on the thermal, optical, electronic and charge transport properties of the polymers have been investigated. These solution processable polymers exhibit p-channel field-effect charge transport characteristics, unlike other organic NDI-based polymeric analogues. All the results indicated that they have potential applications in high-performance organic field-effect transistors (OFETs).Download high-res image (252KB)Download full-size image

•New platinum(II)-containing metallopolyyne polymer is prepared.•The metallopolymer acts as a precursor towards the synthesis of Pt nanoparticles.•The formed nanoparticles are characterized by TEM, EDXA and PXRD.In this study, we report the synthesis and characterization of a new bis(pyridyl)-coordinated platinum(II)-containing metallopolyyne polymer. It is found that this metallopolymer can act as a precursor towards the synthesis of Pt nanoparticles upon pyrolysis (600 °C, 5 h). The resultant nanoparticles were characterized by transmission electron microscope (TEM), energy-dispersive X-ray analysis (EDXA) and powder X-ray diffraction (PXRD). The results verify that monodisperse Pt nanoparticles with defined morphology can be obtained. This pilot study reveals the potential of fabricating patterned Pt nanoparticles by using various lithographic methods in the future.A new bis(pyridyl)-coordinated platinum(II)-containing metallopolyyne polymer was prepared, which can act as a precursor towards the synthesis of Pt nanoparticles upon pyrolysis.Download high-res image (122KB)Download full-size image

•Bimetallic complexes containing Fe and Pd were prepared.•Ferromagnetic FePd nanoparticles were synthesized by one-pot pyrolysis of these single-source precursors.•The size of FePd nanoparticles was tuned by controlling the ratio of the metal fraction in the precursors.The accurate regulation of the size of the ferromagnetic nanoparticle synthesized from the one-pot pyrolysis of metallopolymer is a challenging topic to date. A bimetallic complex TPy-FePd-1 was prepared and used as a single-source precursor to synthesize ferromagnetic FePd nanoparticles (NPs) by one-pot pyrolysis. The resultant FePd NPs have a mean particle size of 19.8 nm and show a coercivity of 1.02 kOe. In addition, the labile ligand NCMe in TPy-FePd-1 was easily substituted by a pyridyl group. A random copolymer PS-P4VP was used to coordinate with TPy-FePd-1, and the as-synthesized metallopolymer made the metal fraction disperse evenly along the flexible chain. Investigation of FePd NPs from the bimetallic polymers with different metal fractions was also made, and the size of the resultant nanoparticles could be easily controlled by tuning the metal fraction in the polymer.A bimetallic complex TPy-FePd-1 was used as a single-source precursor to synthesize ferromagnetic FePd nanoparticles by a one-pot pyrolysis. In addition, metallopolymers with different metal fractions derived from TPy-FePd-1 were prepared and the size of FePd NPs from these polymer precursors increased linearly with the metal content.Download high-res image (192KB)Download full-size image

•Iridium complexes incorporate with the electron-rich thiazolyl group were designed and synthesized.•The emission color of these thiazole-based Ir(III) complexes can be tuned from yellow to red.•The best phosphorescent organic light-emitting device exhibited the maximum external quantum efficiency of 11.1%, current efficiency of 35.8 cd/A and power efficiency of 21.9 lm/W.With respect to the commonly used electron-deficient pyridyl group in the benchmark dopant Ir(ppy)3, incorporating the electron-rich thiazolyl group with different chromophores have not been extensively studied. In this paper, some iridium(III) complexes bearing functional ligands with the thiazolyl moiety were synthesized and characterized by 1H and 13C NMR, UV–Vis absorption and photoluminescence spectroscopy. The emission color of these thiazole-based Ir(III) complexes can be tuned from yellow to red and the best phosphorescent organic light-emitting device exhibited the maximum external quantum efficiency of 11.1%, current efficiency of 35.8 cd/A and power efficiency of 21.9 lm/W.New thiazole-based iridium(III) phosphors were synthesized. Their emission colors could be tuned from yellow to red. The best OLED exhibited a maximum external quantum efficiency of 11.1%, current efficiency of 35.8 cd/A and power efficiency of 21.9 lm/W.Download high-res image (280KB)Download full-size image

This review focuses on the recent development in the rigid-rod metallopolymers of late transition metals based on triple-bond building blocks. The synthesis, structure–property relationships and potential applications of organometallic poly(arylene ethynylene)s will be discussed in detail. These functional metal-based polymers can exhibit intriguing optical, electronic and magnetic properties. Considerable focus is placed on the design strategies towards tuning the optical bandgap and emission color (spanning almost the whole visible spectrum) of this class of metallopolymers, and the investigation of their use as active materials for light/electrical energy conversion and energy and information storage. The ongoing scientific challenges and future prospects of this research field are also highlighted.

A tetraphenylethene-containing dipyrrin (TPEpy) has been synthesized and its photophysical properties and metal detecting properties have been investigated. TPEpy displays a high selectivity and sensitivity with a detection limit of 8.96 × 10−8 M for Zn2+ in aqueous media.A tetraphenylethene-containing dipyrrin (TPEpy) displays a high selectivity and sensitivity with a detection limit of 8.96 × 10−8 M for Zn2+ in aqueous media.Download high-res image (251KB)Download full-size image

A new series of small-molecular ruthenium(II)-diynes trans-Ru(dppe)2(C≡CAr)2 (D1−D4) (dppe = Ph2CH2CH2Ph2; Ar = aromatic moiety) have been successfully designed, synthesized and characterized by photophysical, electrochemical and computational methods, and complexes D1 and D3 were crystallographically characterized. The optical and time-dependent density functional theory studies showed that the absorption ability of these complexes was significantly enhanced by incorporating the stronger electron-donor groups. The effect of different electron-donor groups in these metallo-organic complexes on the optoelectronic and photovoltaic properties was also examined. In this work, benzothiadiazole as the electron acceptor and triphenylamine and/or thiophene as the electron donor were introduced in these complexes, which were found to have optimal energy bandgaps spanning from 1.70 to 1.83 eV and broad absorption bands within 300–700 nm, rendering them good electron donor materials to blend with [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) in the fabrication of the solution-processed bulk heterojunction (BHJ) solar cells. The best power conversion efficiency (PCE) of 0.66% was achieved, which is the highest PCE in ruthenium(II)-containing BHJ solar cells to date.Download high-res image (116KB)Download full-size image

Four new conjugated ferrocene-containing poly(fluorenylethynylene)s (PFcFE1–PFcFE4) with triphenylamine, carbazole or thiophene moieties in the main chain have been designed and synthesized via a Sonogashira coupling reaction. Their structures, molecular weights, optical features, thermal properties and memory performance were well studied. Two terminal single layer devices (ITO/polymer/Al) based on PFcFE1, PFcFE2 and PFcFE3 exhibited flash memory behaviours, while PFcFE4 shared the common characteristics of the “write-once read-many times” (WORM) memory effect. These results would provide a new series of ferrocene-containing conjugated polymers with further opportunities for memory applications.

A series of new D–π–A organic photosensitizers 7a–7d featuring a novel starburst electron donor unit and uncommon selenophene containing π-linker were synthesized, characterized, and applied for fabrication of dye-sensitized solar cells (DSSCs). Dyes 11d–13d with thiophene or phenyl ring as the π-linker also were synthesized for comparison. The best power conversion efficiency (PCE) of 6.67% was attained for 11d with a relatively high open-circuit voltage (Voc) of 0.825 V using conventional I−/I3− redox electrolyte in DSSCs, and this value reaches about 84% of the device based on standard dye N719 (7.91%) under the same device fabrication conditions. Electrochemical impedance spectroscopy (EIS) and open-circuit voltage decay (OCVD) were applied to verify the findings. All the results suggest that starburst electron donor design strategy can be used to minimize dye aggregation on TiO2 and to slow down the charge recombination kinetics in DSSCs to improve the photovoltaic performance. Effects of using selenophene as the π-linker building block on the photovoltaic parameters also were explored and evaluated.

Bit-patterned media (BPM) with a precise stoichiometry ratio of Fe and Pt atoms are promising for future high areal density magnetic recording. Here, we report a new FePt-containing metallopolymer P as the single-source precursor for the synthesis of magnetic metal alloy nanoparticles. This polymer was synthesized from a random copolymer poly(styrene-4-ethynylstyrene) PES-PS and the bimetallic precursor TPy-FePt ([Pt(4′-ferrocenyl-(N^N^N))Cl]Cl) by the CuI-catalyzed dehydrohalogenation. After pyrolysis of P, the stoichiometry of Fe and Pt atoms in the synthesized nanoparticles is nearly close to 1:1, which is more precise than that by using TPy-FePt as the precursor. Also, polymer P is more suitable for patterning by high-throughput nanoimprint lithography (NIL) compared to TPy-FePt. Ferromagnetic nanolines, potentially useful for fabricating bit-patterned magnetic recording media, were successfully obtained from P and fully characterized.

•Platinum- and palladium-diazafluorene complexes were synthesized.•They showed in vivo antitumour activity against Hep3B xenografted model.•They had lower liver ALT and AST than vehicle control.Two complexes dichloro(9,9-dihexyl-4,5-diazafluorene)platinum(II) (Pt-DHF) and dichloro(9,9-dihexyl-4,5-diazafluorene)palladium(II) (Pd-DHF) were synthesized and their in vivo antitumour activity was investigated using an athymic nude mice model xenografted with human Hep3B carcinoma cells. Pt-DHF- and Pd-DHF-treated groups showed significant tumour growth inhibition (with about 9-fold and 3-fold tumour growth retardation) when compared with the vehicle control group. The liver toxicology effects on the animals of the two compounds were investigated. Pt-DHF and Pd-DHF-treated groups had a lower alanine transaminase and aspartate transaminase values than those of the vehicle treated group as the animals from the vehicle control group had very heavy hepatoma burden. We assume that both complexes could be further investigated as effective antitumour agents and it is worthwhile to study their underlying working mechanism.

•New platinum(II) acetylide donor-acceptor (D–A) triads were prepared.•Spectroscopic, redox and structural characterization were carried out.•Bulk heterojunction solar cells using these platinum complexes were fabricated.Six new solution processable platinum(II) acetylide donor-acceptor (D-A) triads end-capped by 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTBT) have been synthesized and characterized by photophysical and electrochemical methods. All these materials possess low bandgaps and strong UV/Vis absorption between 400 and 700 nm. Bulk heterojunction (BHJ) solar cells based on these molecules as donor materials were fabricated. The best power conversion efficiency (PCE) of 1.46% with the open-circuit voltage (Voc) of 0.70 V, short-circuit current density (Jsc) of 6.17 mA cm−2 and fill factor (FF) of 0.33 was achieved under illumination of an AM 1.5 solar cell simulator. These results suggest the potential use of solution-processable small molecular platinum(II)-acetylides for efficient generation in organic photovoltaic implementation.Six new solution-processable platinum(II) acetylide donor-acceptor (D-A) triads end-capped y 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTBT) were synthesized and characterized by photophysical and electrochemical methods. These compounds were also used as active layers in the fabrication of organic solar cells.

•Two new Ir(III) cyclometalates based on 2-thienylpyridine derivatives were synthesized and characterized.•They showed extended absorption features.•They have been applied in bulk heterojunction solar cells as donor materials.Two new iridium(III) cyclometalates (A and B) based on 2-[5-(9,9′-diethyl-9H-fluoren-7-yl)thienyl]-pyridine were synthesized, characterized and applied in bulk-heterojunction solar cells (BHJSCs). Their absorption, electrochemical, thermal and photovoltaic properties have been investigated. The results reveal that the replacement of phenyl ring by thienyl one can extend the absorption wavelength up to 530 nm, thus narrowing the energy gap (Eg) to 2.93 eV and 2.81 eV for A and B, respectively. These complexes exhibit excellent thermal stability with the onset decomposition temperature at 5% weight-loss (Td) of over 370 °C. The BHJSC device with A as donor blended with [6,6]-phenyl C61-butyric acid methyl ester (PCBM) gave the best power conversion efficiency (η) of 0.51%, with a short-circuit photocurrent density (Jsc) of 2.68 mA cm−2, an open-circuit photovoltage (Voc) of 0.66 V and a fill factor (ff) of 0.28 under illumination of an AM 1.5 solar cell simulator.Two new iridium(III) complexes were synthesized, characterized and applied in bulk heterojunction solar cells. The complexes showed extended absorption and decent photovoltaic effect.

•Two platinum(II) polyyne polymers containing ferrocenyl pendant ligands were prepared.•The polymers were used as the cathode-active materials for organic lithium batteries.•The electrodes exhibited good cycle life of over 50 charging/discharging cycles.Two bis(acetylide)-functionalized platinum(II) polymers containing ferrocenyl pendant ligands, trans-[{-Pt(PBun3)2-C≡CRC≡C-}nP1 (R = 9-ferrocenylmethylene-2,7-diethynylfluorene) and P2 (R = ferrocenylmethylene-2,5-diethynylbenzene), were prepared in good yields and were characterized by NMR spectroscopy and GPC. Electrochemical characteristics with copolymers P1 and P2 as the cathode active materials for rechargeable lithium batteries showed chemical and electrochemical reversibility. The thin layer polymer electrodes of P1 and P2 exhibited reversible redox peaks at the potentials of 0.54 and 0.64 V (vs. Ag/AgCl), respectively. The P1 or P2/carbon composites are also used as cathode-active materials to enhance the conductivity and durability. The electrodes exhibited good cycle life of over 50 charging/discharging cycles and no reversible n-type redox abilities seemed to be available.Two bis(acetylide)-functionalized platinum(II) polymers containing ferrocenyl pendant ligands were prepared in good yield and characterized by NMR and GPC. They were used as the cathode-active materials for organic lithium batteries, which showed chemical and electrochemical reversibility for both materials.

•A series of highly efficient triarylamine-based dyes for DSSCs are reviewed.•The influences of molecular structures on photophysical and electrochemical properties together with photovoltaic parameters of DSSCs are presented.Increasing energy demands and environmental concerns about global warming have led to a greater focus on the development of renewable energy sources. Dye-sensitized solar cells (DSSCs) have attracted considerable attention in recent years as they offer the possibility of low-cost conversion of photovoltaic energy. In particular, triarylamine functionalized organic photosensitizers show high molar absorption coefficients in the visible spectral region, good dye aggregation resistance and reliable electrochemical and thermal stabilities. This review emphasizes the recent developments and strategies employed in the structural design of arylamine-based metallated and metal-free organic photosensitizers. The influences of molecular structural engineering on photophysical and electrochemical properties along with photovoltaic parameters and the efficiency of DSSCs are presented. Hence, by drawing a correlation among the structures of arylamine-derived photosensitizers, their properties and photovoltaic parameters of DSSCs, it will be useful in optimizing new dyes for the generation of efficient photovoltaic cells for energy production.

With the worldwide awareness of the energy crisis and low carbon economy, there is an ever-growing demand for renewable energy resources, energy saving products and reliable energy storage devices. Metallopolymers play an increasingly important role as functional materials for energy production, conservation and storage. In this review, we explore the recent advances of metallopolymers in the areas of organic solar cells, white light organic light-emitting diodes and lithium-ion batteries. The structure–property relationship of these polymers and their device performances are paid special attention and described.

Two new poly(fluorenylethynylene)s with ferrocene moieties PFFAL1 and PFFAL2 were designed and synthesized. Their structures, molar masses, photophysical properties and thermal characteristics were analyzed by 1H NMR, Fourier transform infrared (FTIR) spectroscopy, size exclusion chromatography (SEC), ultraviolet–visible (UV–Vis) spectroscopy and thermogravimetric analysis (TGA). The morphologies and electrochemical performances of the polymer-composed cathodes were studied by scanning electron microscopy (SEM), cyclic voltammetry (CV) and galvanostatic charge–discharge test. The results showed that PFFAL1-composed electrode retained over 90% of the initial capacity after 100 cycles at 10 C and PFFAL2-based cathode exhibited a stable discharge capacity of 73 mAh g−1 at 1 C, which is close to the theoretical value (82.3 mAh g−1). The stable capacity as well as the good cycle endurance of these polymer-based coin cells revealed their great potential as cathode-active materials for rechargeable lithium batteries.

Two new solution-processible platinum(II) polyyne polymers P1 and P2 bridged by diketopyrrolopyrrole and isoindigo units have been synthesized via the CuI-catalyzed dehydrohalogenation reaction of the platinum(II) chloride precursors and the corresponding diacetylene ligands. The photophysical and electrochemical properties of P1 and P2 were investigated. These metallo-organic polymers have relatively narrow bandgaps of around 1.58–1.70 eV and broad absorption bands which are favorable for harvesting solar energy.

A series of new fluorene-bridged organic dyes with di-anchoring groups have been synthesized and well characterized. Such a molecular design strategy using two organic anchors inhibits the undesirable charge recombination and prolongs the electron lifetime which results in significant enhancement of the power conversion efficiency (η). These findings were supported by the results from electrochemical impedance spectroscopy (EIS) and open-circuit voltage decay (OCVD). Under standard AM 1.5 irradiation (100 mW cm−2), the best dye-sensitized solar cell (DSSC) exhibits a high η of 6.11% without the need for co-adsorbent addition. An open-circuit photovoltage (Voc) of 0.753 V, a short-circuit photocurrent density (Jsc) of 11.20 mA cm−2 and a fill factor (ff) of 0.725 were measured in such co-adsorbent-free cells. The high Voc value is mainly attributed to the improved electron lifetime (τn) and high resistance to the recombination of electrons (Rrec) of 422.38 Ω.

•A survey of red to near-infrared phosphorescent dyes was provided.•The structure–property–activity relationships of these dyes were discussed.•The phosphorescent OLED applications of these red dopants were described.In modern research on organic light-emitting diodes (OLEDs), cyclometalated iridium(III) complexes represent one of the most studied class of compounds. The high emission efficiency caused by the strong spin-orbit coupling in the presence of heavy metals leads to the mixing of singlet and triplet manifolds so that both the singlet and triplet excitons can be harvested. For OLEDs to be useful in displays application, true red, green, and blue emissions of sufficient luminous efficiencies and proper chromaticity are required. In recent years, the development of materials for phosphorescent red OLEDs has indeed gone through several important evolutional stages. However, the luminescent quantum yields of red-emitting iridium(III) phosphors tend to be intrinsically low which are governed by the energy gap law for triplet states in which the luminescence quantum yields tend to decrease with an increase in the emission wavelength. Many red organic dyes currently in use do not show a good compromise between device efficiency and color purity. In general, a dilemma facing red OLEDs was realized in which efficient and bright dopants are not red enough, and red-enough dopants are not efficient and bright. In this review article, we highlight the recent progress and current challenges of efficient OLEDs based on cyclometalated iridium(III) dyes which exhibit saturated red and near-infrared electroluminescence. Optimization of the phosphorescent red OLED efficiency/color purity trade-off and extension of the work to other organometallic phosphors are also presented and discussed.An overview of the recent progress in the molecular design, synthesis and OLED applications of red phosphorescent dyes is presented in this review article.

Metallophosphors and metallopolyynes of the transition metal elements have recently received considerable attention as molecular functional materials in various areas, such as organic light-emitting diodes, photovoltaic devices, oxygen sensors, optical limiters and two-photon absorption materials, etc. Their photophysics, charge transport and energy transfer mechanism are greatly influenced by the chemical environment around the transition metal center which consequently affects their performances in these applications. Therefore, much current focus has been put on studying the structure–property relationships of functional metallophosphors and metallopolyynes. A deep understanding of these correlations can provide important information in designing molecules which are suitable for a particular optoelectronic application with enhanced performance.

Five bithiazole-based organic dyes D1–D5 containing different electron donor moieties (thiophene, fluorene, carbazole, and triarylamine) in the molecular frameworks were synthesized, characterized and applied in dye-sensitized solar cells (DSSCs). The effects of electron-donating moieties of the organic dyes on their photophysical, electrochemical, and photovoltaic properties have been investigated in detail. These dyes exhibit strong charge transfer absorption bands in the visible region. Their redox potential levels were estimated by cyclic voltammetry and found to match well with the charge flow in DSSCs. The combination of broad absorption bands with fairly high extinction coefficients and appropriate redox properties makes these bithiazole-based molecules promising dyes for DSSCs. For solar cell device based on D4, the maximal monochromatic incident photon-to-current conversion efficiency (IPCE) can reach up to 68.5%, with a short-circuit photocurrent density (Jsc) of 9.61 mA cm−2, an open-circuit photovoltage (Voc) of 0.70 V and a fill factor (FF) of 0.70, which results in a power conversion efficiency (PCE) of 4.65% under illumination of an AM 1.5 solar cell simulator.Graphical abstractThe synthesis, characterization and photovoltaic properties of a new series of bithiazole-based organic photosensitizers were presented. These organic dyes are promising materials for dye-sensitized solar cells with the best power conversion efficiency of 4.7%. The photovoltaic response depends significantly on the nature of the electron-donating end group. Highlights► We report new bithiazole-based organic dyes containing different electron donor moieties. ► Dye-sensitized solar cells (DSSCs) are fabricated using these dyes. ► The performance of DSSCs depend significantly on the nature and strength of the electron-donating end group. ► The maximal power conversion efficiency of DSSCs can reach up to 4.65%.

•We report fluorenone-containing organic sensitizers for dye-sensitized solar cells.•Effect of different electron donors on the photovoltaic performance was studied.•The maximal power conversion efficiency of 4.71% was achieved.Four new organic dyes (F1–F4) comprising the triarylamine or fluorene unit as an electron-donating group, a less commonly used fluorenone spacer and a cyanoacrylic acid as the anchoring group in the molecular framework were synthesized, characterized and utilized in dye-sensitized solar cells (DSSCs). Their absorption, photoluminescence, electrochemical and photovoltaic properties were fully investigated in detail. Electrochemical data indicate that the tuning of the HOMO and LUMO energy levels can be conveniently accomplished by alternating the donor moiety. The photovoltaic performance can be increased by adding an electron-donating triarylamine or fluorene unit next to the fluorenone ring or increasing the number of thienyl ring next to the cyanoacrylic acid group, which is consistent with the results from electrochemical impedance spectroscopy. The maximal monochromatic incident photon-to-current conversion efficiency (IPCE) can reach up to 80% for DSSC devices based on F4 with the overall light to electricity conversion efficiency up to 4.71% (Voc = 565 mV, Jsc = 11.71 mA cm−2 and FF = 0.71) under AM 1.5 irradiation (100 mW cm−2).A new family of fluorenone-based organic photosensitizers were described. The photovoltaic response can be enhanced by adding an electron-donating triarylamine or fluorene unit next to fluorenone or increasing the number of thienyl ring next to cyanoacrylic acid. These dyes showed the best power conversion efficiency of 4.71% in nanostructured dye-sensitized solar cells.

Organic light-emitting devices (OLEDs) are on the lips of most electronic manufacturers currently. With good progress made in terms of production cost, efficiency and color output, OLEDs have found more applications recently as compared to those some years ago. Because of the possibility of obtaining long-lasting, durable and energy-efficient OLEDs, researchers devote much time and effort towards the improvement of OLED technology and development of advanced OLED products. Blue light-emitting materials, especially blue phosphorescent materials, are indispensable for full-color displays and white OLED lighting. Compared with green and red light-emitting materials and devices, the blue-emitting counterparts show a relatively inferior performance in terms of color purity, luminescence efficiency and device durability. In this perspective article, we highlight the recent progress and current challenges of blue-emitting metallophosphors based on small molecules and their applications in phosphorescent OLEDs.

Five new thiocyanate-free ruthenium(II) complexes with different electron-donating functionalized cyclometalating ligands C^N were synthesized, characterized and applied as photosensitizers in dye-sensitized solar cells (DSSCs). Their photophysical, electrochemical, thermal and photovoltaic properties have been investigated and density functional theory (DFT) calculations have been carried out on these dyes. These dyes exhibit good thermal stability with the onset decomposition temperature at 5% weight-loss (Td) of around 330 °C. The DSSC device using the Ru(II) dye with the 9-tolylcarbazole chromophore exhibited the highest power conversion efficiency (η) up to 3.39%, with a short-circuit photocurrent density (Jsc) of 8.06 mA cm−2, an open-circuit photovoltage (Voc) of 0.62 V and a high fill factor (ff) of 0.68 under illumination of an AM 1.5 solar cell simulator.Five new thiocyanate-free ruthenium(II) complexes with different electron-donating functionalized cyclometalating ligands C^N were synthesized and characterized by both spectroscopic and theoretical computational methods. These compounds were also used as dyes in the fabrication of dye-sensitized solar cells.Download full-size image

A series of new fluorene-bridged organic dyes with di-anchoring groups have been synthesized and well characterized. Such a molecular design strategy using two organic anchors inhibits the undesirable charge recombination and prolongs the electron lifetime which results in significant enhancement of the power conversion efficiency (η). These findings were supported by the results from electrochemical impedance spectroscopy (EIS) and open-circuit voltage decay (OCVD). Under standard AM 1.5 irradiation (100 mW cm−2), the best dye-sensitized solar cell (DSSC) exhibits a high η of 6.11% without the need for co-adsorbent addition. An open-circuit photovoltage (Voc) of 0.753 V, a short-circuit photocurrent density (Jsc) of 11.20 mA cm−2 and a fill factor (ff) of 0.725 were measured in such co-adsorbent-free cells. The high Voc value is mainly attributed to the improved electron lifetime (τn) and high resistance to the recombination of electrons (Rrec) of 422.38 Ω.

Four new conjugated ferrocene-containing poly(fluorenylethynylene)s (PFcFE1–PFcFE4) with triphenylamine, carbazole or thiophene moieties in the main chain have been designed and synthesized via a Sonogashira coupling reaction. Their structures, molecular weights, optical features, thermal properties and memory performance were well studied. Two terminal single layer devices (ITO/polymer/Al) based on PFcFE1, PFcFE2 and PFcFE3 exhibited flash memory behaviours, while PFcFE4 shared the common characteristics of the “write-once read-many times” (WORM) memory effect. These results would provide a new series of ferrocene-containing conjugated polymers with further opportunities for memory applications.

A series of new D–π–A organic photosensitizers 7a–7d featuring a novel starburst electron donor unit and uncommon selenophene containing π-linker were synthesized, characterized, and applied for fabrication of dye-sensitized solar cells (DSSCs). Dyes 11d–13d with thiophene or phenyl ring as the π-linker also were synthesized for comparison. The best power conversion efficiency (PCE) of 6.67% was attained for 11d with a relatively high open-circuit voltage (Voc) of 0.825 V using conventional I−/I3− redox electrolyte in DSSCs, and this value reaches about 84% of the device based on standard dye N719 (7.91%) under the same device fabrication conditions. Electrochemical impedance spectroscopy (EIS) and open-circuit voltage decay (OCVD) were applied to verify the findings. All the results suggest that starburst electron donor design strategy can be used to minimize dye aggregation on TiO2 and to slow down the charge recombination kinetics in DSSCs to improve the photovoltaic performance. Effects of using selenophene as the π-linker building block on the photovoltaic parameters also were explored and evaluated.