A novel approach for enhancing the performance of dye-sensitized solar cells is presented. It is based on the analysis of five sensitizers by utilizing triarylamine as donor, thiophene benzothiadiazole as chromophore and substituted thienyl linked with cyanoacrylic acid as the anchoring group (LI-80-LI-84). Accompanied with the increasing steric hindrance of the substituents on the thienyl isolation group, the conformation of the dyes, in particular the angle between the chromophore and the anchoring group, becomes more and more twisted. Surprisingly, sensitizers with poorer conjugation effects (the higher twisted conformation) achieve better photovoltaic performances, showing a contrary trend to the traditional donor-(π-spacer)-acceptor dyes with a better co-planarity. On the basis of the preceding fundamental comprehensions, an empirical method is successfully applied to a new phenyl-based system (LI-85 and LI-86) to improve their performances. The systematical investigation indicates that the twisted structures can contribute to the E_CB of the TiO₂ film, electron lifetime and resistance at the TiO₂/dye/electrolyte interface. Thereby, the efficiency of the initial LI-80-based cell has been dramatically improved to 2.45 times higher for LI-86-based cell, paving a new way for the design of better sensitizers with higher device performances.

Great efforts have been devoted to seek novel approaches for constructing blue fluorescent materials, which is one of the most important prerequisites for the commercialization of OLEDs. In recent years, various outstanding luminogens with aggregation-induced emission characteristic exhibit promising applications as emitters, but blue AIE fluorophores with excellent EL performance are still very scarce. Here, five hole-dominated blue AIE molecules are demonstrated by adopting construction approaches of changing linkage modes and increasing intramolecular torsion together, with the aim to restrict conjugation lengths without sacrificing good EL data. Device results show that the novel synthesized materials could be applied as bifunctional materials, namely blue light-emitting and hole-transporting materials, with comparable EL efficiencies, and the η_C,max and η_ext,max are up to 8.03 cd A⁻¹ and 3.99% respectively, which is among the best EL performance for blue AIE luminogens.

Three TPE trimers with meta or para linkage modes have been successfully synthesized. When fabricated as emissive layers in non-doped OLEDs, they all exhibit blue or deep-blue emissions with maximum current efficiency up to 4.03 cd A⁻¹, further verifying the facile but ingenious approach by utilizing meta-linkage mode in longer conjugated systems.

Two aggregation-induced emission active luminogens (TPE–pTPA and TPE–mTPA) were successfully synthesized. For comparison, another six similar compounds were prepared. Because of the introduced hole-dominated triphenylamine (TPA), fluorene groups with high luminous efficiency, and unconjugated linkages, the π conjugation length of the obtained luminogens is effectively restricted to ensure their blue emission. The undoped organic light-emitting diodes based on TPE–pTPA and TPE–mTPA exhibited blue or deep-blue emissions, low turn-on voltages (3 V), and high electroluminescence efficiencies with L_max, η_C,max, and η_P,max values of up to 26 697 cd m⁻², 3.37 cd A⁻¹, and 2.40 Lm W⁻¹.

Four 4,4′-bis(1,2,2-triphenylvinyl)biphenyl (BTPE) derivatives, 4,4′-bis(1,2,2-triphenylvinyl)biphenyl, 2,3′-bis(1,2,2-triphenylvinyl)biphenyl, 2,4′-bis(1,2,2-triphenylvinyl)biphenyl, 3,3′-bis(1,2,2-triphenylvinyl)biphenyl and 3,4′-bis(1,2,2-triphenylvinyl)biphenyl (oTPE-mTPE, oTPE-pTPE, mTPE-mTPE, and mTPE-pTPE, respectively), are successfully synthesized and their thermal, optical, and electronic properties fully investigated. By merging two simple tetraphenylethene (TPE) units together through different linking positions, the π-conjugation length is effectively controlled to ensure the deep-blue emission. Because of the minor but intelligent structural modification, all the four fluorophores exhibit deep-blue emissions from 435 to 459 nm with Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of, respectively, (0.16, 0.14), (0.15, 0.11), (0.16, 0.14), and (0.16, 0.16), when fabricated as emitters in organic light-emitting diodes (OLEDs). This is completely different from BTPE with sky-blue emission (0.20, 0.36). Thus, these results may provide a novel and versatile approach for the design of deep-blue aggregation-induced emission (AIE) luminogens.

Two new alkoxy-substituted quinoxaline (Qx)-based copolymers, PBDTQx and PBDTPz, are designed and synthesized. The only difference between these two polymers is that two methyl groups of the Qx are replaced by one additional fused benzene ring. The UV–Vis absorptions, thermal stability, energy levels, field-effect carrier mobility, and photovoltaic characteristics of the two copolymers are systematically evaluated to understand the relationships between the polymer structure at the molecular level and the photovoltaic performances. Photovoltaic cells based on the PBDTPz with a structure of ITO/PEDOT:PSS/Polymer:PC₇₁BM/PEO/Ca/Al exhibit a promising efficiency of 4.40%, while that of PBDTQx is relatively much poorer.

Through the combination of the divergent and convergent approaches, coupled with the utilization of the powerful Sharpless “click-chemistry” reaction, two series of sulfonyl-based high-generation NLO dendrimers were conveniently prepared with high purity and in satisfactory yields. Thanks to the perfect three-dimensional (3D) spatial isolation from the highly branched structure and the isolation effect of the exterior benzene moieties and the interior triazole rings, these dendrimers exhibited large second harmonic generation coefficient (d₃₃) values up to 181 pm V⁻¹, which, to the best of our knowledge, is the highest value so far for polymers containing sulfonyl-based chromophore moieties. Meanwhile, compared with the nitro-chromophore-based analogues, their optical transparency and NLO stability were improved in a large degree, due to the lower dipole moment (μ) and the special main-chain structure of sulfonyl-based chromophore in these dendrimers.

Herein, through a combination of divergent and convergent approaches, coupled with the utilization of the powerful Sharpless “click chemistry” reaction, two series of high-generation nonlinear optical (NLO) dendrimers have been conveniently prepared in high purity and satisfactory yields. Perfluoroaromatic rings and isolation chromophores were introduced to further improve their comprehensive performance. Thanks to the effects of ArAr^F self-assembly and the isolation chromophores, coupled with perfect 3D spatial isolation from the highly branched structure of the dendrimer, G5-PFPh-NS displayed very large NLO efficiency (up to 257 pm V⁻¹), which is, to the best of our knowledge, the new record highest value reported so far for simple azo chromophore moieties. High-quality wide optical transparency and good stability were also achieved.

For the first time, a series of second-order NLO poly(arylene-ethynylene)s, in which an isolation chromophore was introduced to enhance the NLO coefficients, were successfully designed and synthesized. Thanks to the isolation chromophore, these polymers demonstrated good NLO activities and optical transparency. To further improve the comprehensive performance of the polymers, different isolation groups of various sizes were introduced to subtly modify the structure of the polymers according to the “suitable isolation group” concept. The naphthalene (Np) group was found to be a “suitable isolation group” in this series of polymers and polymer P3 demonstrated the highest d₃₃ value (122.1 pm V⁻¹) of these five polymers. Interestingly, polymer P5, which contained a pentafluorophenyl ring as an isolation group, exhibited a much higher NLO effect and stability than polymer P2, which just contained normal phenyl rings as isolation groups (97.2 versus 62.5 pm V⁻¹), thus indicating the advantages of the ArAr^F self-assembly effect in the field of non-linear optics.

In this study, a new polymer P1 embedded with “H”-type chromophore moieties was designed and synthesized through Suzuki coupling copolymerization, in which the isolation chromophore was introduced to further improve its comprehensive performance. This polymer demonstrated good solubility and film-forming ability. In comparison with normal ”H”-shaped NLO polymers only containing one type of chromophore, nearly all the performance of P1 was improved. Its NLO coefficient was as high as 134 pm V⁻¹, and its onset temperature for decay was up to 150 °C. Coupled with its improved optical transparency, all these properties made it a promising candidate for practical applications in photonic fields.

With the aim to develop new tetraphenylethylene (TPE)-based conjugated hyperbranched polymer, TPE units, one famous aggregation-induced emission (AIE) active group, are utilized to construct hyperbranched polymers with three other aromatic blocks, through an “A₂+B₄” approach by using one-pot Suzuki polycondensation reaction. These three hyperbranched polymers exhibit interesting AIEE behavior and act as explosive chemsensors with high sensitivity both in the nanoparticles and solid states. This is the first report of the AIE activity of the TPE-based conjugated hyperbranched polymers. Their corresponding PLED devices also demonstrate good performance.

Two new propeller-shaped D-π-A organic sensitizers that contain two tetraphenylethylene (TPE) moieties in the donor part of the triphenylamine group have been designed and characterized. These dyes are composed of the same donor and acceptor units with different aromatic units introduced through linkers between the donor and acceptor units. The dye-sensitized solar cells (DSCs) based on LI-31 with 10 mM chenodeoxycholic acid (CDCA) show the best light-to-power conversion efficiency of 6.77 % (J_sc = 14.69 mA cm^–2; V_oc = 0.74 V; fill factor: ff = 0.62) under standard global AM 1.5 solar light conditions (100 mW cm^–2).

Covalently functionalized reduced graphene oxide (RGO) sheet was prepared by treating nitrogen-centered anions generated from poly(9,9′-diheylfluorene carbazole) (PCF) with GO. The resultant hybrids with different chemical behavior were separated by centrifugation. The covalent modification was fully characterized by IR spectroscopy, UV/Vis spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, TEM, and SEM. It was found that RGO-PCF-s, the soluble part, was split into small platelets with a size of about 200 nm, and the hydrophobic polymer PCF became hydrophilic after wrapping by RGO. The content of RGO in RGO-PCF-s was about 11.9 %, and the hybrid material showed good dispersion stability in water. Besides, RGO-PCF-i, the insoluble part, with larger size, displayed excellent optical-limiting response, in which both nonlinear absorption and nonlinear scattering play important roles. As nitrogen-centered anions are an important type of intermediates in chemistry, this one-step “grafting-to” strategy could be used to obtain RGO-based materials with different applications.

Herein, high-generation dendrimers G4-NS and G5-NS, which contained 30 and 62 azo-benzene chromophore moieties, respectively, were conveniently prepared in high purity and satisfied yields by a combination of divergent and convergent approaches, coupled with the utilization of the powerful Sharpless click reaction. These dendrimers possessed a regular structure of alternating layers of nitro-based and sulfonyl-based azo chromophores in which the sulfonyl-based azo-chromophore moieties were utilized as co-isolation groups for the nitro-based moieties to achieve larger macroscopic second-order nonlinear optical (NLO) effects. These high-generation dendrimers (G4-NS and G5-NS) displayed very large NLO efficiencies (up to 253.0 pm V⁻¹), which is, to the best of our knowledge, the record highest efficiency for simple azo-chromophore moieties.

By intelligently utilizing the different interacting strengths between different moieties according to the displacement method, general biosensors with aggregation-induced emission (AIE) characteristics for biomacromolecules without selectivity were converted to excellent, highly selective probes for one specific biomacromolecule with the aid of graphene oxide (GO) in an aqueous medium. Importantly, thanks to the different interactions between the AIE molecule and biomacromolecules, just by simply changing the AIE molecule the sensing system could detect different types of biomacromolecules, thereby providing a new approach to the development of AIE-based sensors with high selectivity and sensitivity. More specifically, the complex of A₂HPS⋅HCl—a derivative of hexaphenylsilone (HPS) functionalized by two amino (A₂) groups (N(CH₂CH₃)₃)—and GO only gives an “off–on” response to DNA, with a detection limit of 2.3 μg mL⁻¹ toward DNA-CT (calf thymus); interestingly, the complex of TPE-N₂C₄ (1,2-bis{4-[4-(N,N,N-triethylammonium)butoxy]phenyl}-1,2-diphenylethene dibromide) and GO could only detect the presence of bovine serum albumin (BSA), whereas other biomacromolecules, including DNA, RNA, and even other proteins have very little influence.

By modifying a synthetic procedure, two new hyperbranched polytriazoles (HP1 and HP2) containing isolation chromophores were synthesized successfully through click chemistry reactions under copper(I) catalysis. For the first time, these two polymers were derived from an AB₄-type monomer, although they contain different end-capping chromophores. They are soluble in normal polar organic solvents and are well characterized. Thanks to the presence of the isolation chromophore, the two polymers demonstrate good nonlinear optical (NLO) properties and optical transparency, making them promising candidates for practical applications.

A new series of intramolecular-charge-transfer (ICT) molecules (compounds 1, 2, and 3) were synthesized by attaching various electron-donating thiophenes groups to a triphenylamine backbone with an aldehyde group as the electron acceptor. Based on the protection reaction between ethanethiol and aldehyde, the corresponding dithioacetals (compounds S1, S2, and S3) were prepared to serve as novel colorimetric and fluorescent chemosensors for Hg²⁺ ions. Also, compound S1 was further utilized to construct the chemical-reaction-based conjugated polymer probe (PS1) towards Hg²⁺ ions. In the presence of as little as 10 nM Hg²⁺, compound PS1 displayed an apparent change in the fluorescent intensity. The sensing processes were revealed to be mediated by ICT, as confirmed by time-dependent DFT calculations. Furthermore, compound S1 was successfully applied to microscopic imaging for the detection of Hg²⁺ in HeLa cells with ratiometric fluorescent methods.

In this article, a facile route was designed to prepare four new hyperbranched poly(arylene-ethynylene)s containing azo-chromophore moieties through one-pot “A₂+B₃” approach via simple Sonogashira coupling reaction. The polymers were all soluble in organic solvents and demonstrated good nonlinear optical (NLO) properties, because of the three-dimensional spatial isolation effect of these hyperbranched polymers. Due to the different B₃-type comonomer, the self-assembly effect of pentafluoroaromatic in the interior of these polymers were different, leading to the different trends of the NLO activities. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Three 2,3-bis(5-hexylthiophen-2-yl)-6,7-bis(octyloxy)-5,8-di(thiophen-2-yl)-quinoxaline (BTTQ)-based conjugated polymers, namely, PF-BTTQ (P1), PP-BTTQ (P2), and PDCP-BTTQ (P3), were successfully synthesized for efficient polymer solar cells (PSCs) with electron-rich units of fluorene and dialkoxybenzene and electron-deficient unit dicyanobenzene, respectively. All the polymers exhibited good solubility in common organic solvents and good thermal stability. Their deep-lying HOMO energy levels enabled them good stability in the air and the relatively low HOMO energy level assured a higher open circuit potential when used in PSCs. Bulk-heterojunction solar cells were fabricated using these copolymers blended with a fullerene derivative as an acceptor. All of them exhibited promising performance, and the best device performance with power conversion efficiency up to 3.30% was achieved under one sun of AM 1.5 solar simulator illumination (100 mW/cm²). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Taking advantage of both the well-known azobenzene structure and the special fluoride-promoted cleavage reaction of the SiO bond, a new ratiometric colorimetric probe (F-1) toward the fluoride anion was designed and synthesized by using intramolecular charge transfer (ICT) as a signal mechanism. Upon the addition of F⁻ ions, the probe displayed apparent color changes from colorless to deep blue, with a dramatic shift of the maximum absorption wavelength (≈230 nm). With the aid of UV/Vis measurements, the detection limit could be as low as 15 μM. The probe possessed much higher selectivity for fluoride over other common anions. Excitingly, by virtue of a “dipstick” approach, F-1 could serve as colorimetric probe for convenient measurements, without the requirement of any additional equipment.

In this paper, four new nonlinear optical (NLO) polyurethanes (P1–P4) were designed and synthesized, and according to the concept of “suitable isolation group,” the subtle structure of the obtained polymers were modified by the introduction of isolation groups in different sizes to adjust their properties via Sonogashira coupling reaction. All the polymers were well characterized and the second harmonic generation (SHG) experiment results demonstrated that BOP groups were the suitable isolation groups in this system, and the corresponding polymer P2 exhibited a larger d₃₃ value than other polymers. Thus, the obtained results further confirmed our original idea and were consistent with the concept of “suitable isolation group.” Copyright © 2009 John Wiley & Sons, Ltd.

Based on our previous work on the sensitive and selective conjugated fluorescent polymeric sensors toward cyanide, 2,1,3-benzothiadiazole and 4,7-bis(thiophen-2-yl)-2,1,3-benzothiadiazole were incorporated into the polyfluorene backbone to yield three new polymers bearing imidazole moieties in the side chains, with different fluorescence color. The fluorescence could be turned off by Cu²⁺ ions and then recovered on addition of cyanide, making them good cyanide sensors with the detection limit down to 1.9 μM. Moreover, by fully understanding this “turn off–turn on” strategy and using the cooperation of two polymers with different fluorescence color, the emission color of the mixture system of one of the imidazole-containing polymers and one from the corresponding polymers without imidazole ones, could be adjusted by the concentrations of the added copper and cyanide ions, leading to the output fluorescent signals diversity. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Three novel conjugated polymers with N-arylpyrrole as the conjugated bridge were designed and synthesized, which emitted strong one- or two-photon excitation fluorescence in dilute tetrahydrofuran (THF) solution with high quantum yields. The maximal two-photon absorption (TPA) cross-sections of the polymers, measured by the two-photon-induced fluorescence method using femtosecond laser pulses in THF, were 752, 1114, and 1869 GM, respectively, indicating that the insertion of electron-donating or electron-withdrawing moieties into the polymer backbone could benefit to the increase of the TPA cross-section. Their large TPA cross-sections, coupled with the relatively high emission quantum yields, made these conjugated polymers attractive for practical applications, especially two-photon excited fluorescence. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

In this article, according to the concept of “suitable isolation group,” six new AB₂-type polytriazoles containing azo-chromophore moieties, derived from the same hyperbranched polymer intermediate, were successfully prepared through click reaction under copper(I) catalysis by modifying the synthetic route, in which different isolation groups in different size were introduced to the periphery of the hyperbranched polymers as end-capping moieties. With the different end-capping groups, these hyperbranched polymers, P1–P6, exhibited different solubility and processability; also, their nonlinear optical properties were modified accordingly, realizing the adjustment of the properties of hyperbranched polymers through the structural design. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

In this paper, four new hyperbranched polytriazoles containing azo moieties, derived from different AB₂-type monomers, were successfully prepared through the “click” chemistry reaction under copper(I) catalysis by modifying the synthetic route. The polymers were soluble in organic solvents and exhibited good second-order nonlinear optical (NLO) properties. Thanks to the self-assembly of perfluoroaromatic moieties in the periphery, HP2 showed the best NLO properties, with the d₃₃ value as high as 145.0 pm V⁻¹.

We report a simple fluorescence method for detection of cyanide sensitively and selectively based on the dissolution of polymer-coated gold nanoparticles by cyanide. The lowest concentration for quantification of cyanide ions was 3.0×10⁻⁷ M, and other common anions nearly have no influence. Furthermore, several real water samples spiked with cyanide, including local groundwater, tap water, boiled water, and lake water, were analyzed, and the experimental results demonstrated that our sensing system worked well in the above water samples, with a good linear correlation.

Two new highly selective colorimetric chemosensors for Hg²⁺, based on azobenzene and highly selective Hg²⁺-promoted deprotection of a dithioacetal have been designed and synthesized. In the presence of as little as 20 μM Hg²⁺, the sensors change their color from light yellow to deep red, which can easily be observed by the naked eye. The underlying signaling mechanism is intramolecular charge transfer (ICT). The sensors have good selectivity for Hg²⁺ with respect to several common alkali, alkaline earth, and transition metal ions. Furthermore, they can be used for in-the-field measurements by virtue of a dipstick approach without any additional equipment.

A new hyperbranched polymer (HB-car), constructed fully by carbazole moieties, is successfully synthesized through a one-pot Suzuki coupling reaction. The resultant polymer is well-characterized, and its hole-transporting ability is studied carefully. The device, in which HB-car is utilized as a hole-transporting layer and tris-(8-hydroxyquinoline) aluminum as an electron-emitting layer as well as electron-transporting layer, gives a much higher efficiency (3.05 cd A^–1), than that of a poly(N-vinylcarbazole) based device (2.19 cd A^–1) under similar experimental conditions. The remarkable performance is attributed to its low energy barrier and enhanced hole-drifting ability in the HB-car based device. In addition, for the first time, a field-effect transistor (FET) based on the hyperbranched polymer is fabricated, and the organic FET device shows that HB-car is a typical p-type FET material with a saturation mobility of 1 × 10^–5 cm² V^–1 s^–1, a threshold voltage of –47.1 V, and an on-to-off current ratio of 10³.

A series of new indole-based luminophores (IIa–d) were conveniently synthesized through Ullmann reactions. They were well characterized by spectroscopic analyses and exhibited aggregation-induced emission enhancement (AIEE) properties. By simply changing the aromatic moieties in IIa–d, their maximum emission wavelengths could be well-tuned from 340 to 400 nm. The obtained experimental results, including the fluorescent behavior and the crystal structure in solid, demonstrated that the AIEE phenomena are caused by the restrictions of the intramolecular indolyl vibrational and rotational motions (around the Carbon–Nitrogen bonds). Copyright © 2008 John Wiley & Sons, Ltd.

Two new "D-π-D" type triphenylamine-based compounds with a heterocyclic ring, furan or thiophene, as a conjugation bridge were synthesized through a normal Wittig reaction which exhibited good thermal stability and strong luminescence. The preliminary light-emitting diode results indicate that they are promising candidates for the practical application.

A series of poly(vinylcarbazole)-based polymers containing sulfonyl-based nonlinear optical chromophores as the side chains were prepared conveniently through a postfunctionalization approach. In the polymers, the subtle structure of the chromophore moieties could be easily modified by the introduction of different isolation group, to adjust the property of the resultant polymers. The polymers exhibited good optical transparency, besides their good processability and thermal stability. The poled polymer films exhibited large second harmonic generation (SHG) coefficients of d₃₃ values (up to 28.6 pm/V) with excellent thermal stability (about 90% of the maximal SHG coefficients remain at ∼ 110 °C). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2983–2993, 2008

A new imidazole-containing disubstituted polyacetylene (P1) with strong green fluorescence was successfully prepared through polymer reaction, which was nearly impossible to be obtained from the direct polymerization of its corresponding monomer. The polymer was soluble in common organic solvents, and its strong green fluorescence could be quenched completely by the Cu²⁺ and Co²⁺ ions, at the concentrations as low as 1.33 and 1.67 × 10⁻⁵ mol/L (0.85 and 0.92 ppm), respectively. Because of the high stability of the complex formed by cyanide and copper ions, the quenched green fluorescence of P1 by copper ions could be turned on upon the addition of trace cyanide (as low as 2.70 × 10⁻⁵ mol/L, 0.70 ppm), making P1 a new sensitive cyanide chemosensor. The results thus provided a new opportunity to develop anion chemosensors based on good cation chemosensors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8070–8080, 2008