Photoactive Naphthalene Diimide Functionalized Titanium-Oxo Clusters with High Photoelectrochemical Responses

Photoactive functionalized titanium-oxo clusters(TOCs)are regarded as an important model compound for dye-sensitized titanium dioxide solar cells.However,the dyes used for sensitizing TOCs are still limited.Herein,two cyclic TOCs are reported,namely,[Ti_(6)(μ_(3)-O)_(2)(Oi-Pr)_(8))(LA)_(2)]·i-PrOH(S1)and[Ti_(6)(μ_(3)-O)2(Oi-Pr)_(8))(LV)_(2)]·i-PrOH(S2),which are functionalized by photoactive naphthalene diimide(NDI)chromophores.Their molecular structures and photophysical and photochemical properties were systematically studied.As shown by ultraviolet-visible(UV-vis)spectra and photocurrent study results,the band gap and the photocurrent response of S1 and S2 were derived from NDI ligands which extend the absorption edge of S1 and S2 approaching 500 nm and afford high photocurrent densities of 2.12μA/cm^(2)and 1.95μA/cm^(2)for S1 and S2,respectively,demonstrating the significance of the photoactive ligand in modulating photoresponse of TOCs.This work is expected to enrich the structural library of photoactive TOCs and provide insights into understanding the structure-property relationships of sensitized clusters.

Influence of Thickness and Annealing Temperature on the Optical Properties of Spin-Coated Photoactive P3HT:PCBM Blend

Influence of annealing temperature and thickness on the optical characteristics of the blend of poly (3-hexylthiophene) (P3HT) and Phenyl C61 butyric acid methylester (PCBM) layer has been investigated in this report. Photoactive polymer material (P3HT:PCBM) was deposited on indium tin oxide (ITO) substrate by spin-coating. The morphology of P3HT:PCBM composite layer was investigated by Atomic Force Microscope (AFM). The surface roughness was found to reduce after heat treatment. The absorption of the composite layer was found to increase with its number of layer (thickness). On the other hand, the photoluminescence (PL) quenching, which indicates efficient charge separation in the bulk heterojunction, was found higher for the thinner layer. Absorption was also found to increase with the annealing temperature. Therefore, to optimize the thickness of the P3HT:PCBM photoactive layer that will provide best absorption while providing efficient charge separation, annealing at optimized temperature might be an effective tool.

Optical, Photoelectrochemical, and Electrochemical Impedance Studies on Photoactive Organic/Inorganic/Interface Assemblies of Poly 2,2 Bithiophene/Poly 3-(2-Thienyl) Aniline (PThA)/TiO₂

Particles of TiO2 modified with poly 3-(2-thienyl) aniline (PThA) and occluded in poly 2,2 bithiophene (PBTh), were subjected to optical, electrochemical impedance spectroscopic (EIS) and photoelectrochemical (PEC) investigation in aqueous, acetate, citrate, and phosphate electrolytes. EIS studies revealed that the assembly film of TiO2/PThA/PBTh possess porous-type structure. They also confirmed the approximate value of Ef obtained from electrochemical studies. Both EIS and optical studies indicated that ac conductivity is much greater than dc conductivity. Guided by the properties of PBTh, no large changes in the energy band structure occurred due to occlusion of TiO2 in PBTh films. Occlusion of TiO2/PThA into the network structure of PBTh inhibits the energy dissipation process and impeded charge polarization process of the material. Photoelectrochemical outcome suggested possible band alignments between the organic film and TiO2 and formation of hybrid sub-bands. Inclusion of TiO2 in the thiophene-based polymers enhanced the charge separation and consequently charge transfer processes and widen the absorption in visible light range.

Long-Term Activity of Thermoplastic Gel Electrolyte in a Photo-Electrochemical Assembly Involving Poly Bithiophene (PBTh) as Photoactive Working Electrode

Evidence for the long period of a sustainable function of a thermoplastic gel electrolyte (TPGE) consists of polyethylene glycol (PEG)/I2/I- in propylene carbonate (PC) was recorded. The studied photoactive assembly consists of PBTH/FTO/TPGE I2/I-/Platinized FTO. The study showed that the assembly regenerates the expected photoelectrochemical (PEC) quantities such as photocurrent, and other dielectric properties with infrequent use through an elapsed period of 18 months. The behavior of PBTh/occluded with CdS was mentored during this period and showed a similar result. PEC studies indicated the presence of p-p type hole accumulations interface, evident from the initial sharp rise in photocurrent. The change of open circuit potential (dVoc) indicates that the shortest electron lifetime is 100 ms. The behavioral outcome of the assemblies within the period of study refracts stability of the electrode and the long life cycle of the electrolyte.

Photoactive donor-acceptor conjugated macrocycles:New opportunities for supramolecular chemistry

The design and synthesis of photoactive macrocyclic molecules continue to attract attention because such species play important roles in supramolecular chemistry as well as photoelectronic applications.Donoracceptor(D-A)conjugated macrocycles are an emerging class of photoactive molecules due to their D-A conjugated structural characteristics and tunable optical properties.In addition,the well-defined cavities in such D-A macrocycles endow them with versatile host-guest properties.In this review,we provide a comprehensive summary of D-A conjugated macrocycle chemistry,detailing recent progress in the area of synthetic methods,optical properties,host-guest chemistry and applications of the underlying chemistry to chemical sensors,bioimaging and photoelectronic devices.Our objective is to provide not only a review of the fundamental findings,but also to outline future research directions where D-A conjugated macrocycles and their constructs may have a role to play.

A photoactive process cascaded electrocatalysis for enhanced methanol oxidation over Pt-MXene-TiO2 composite

Highly efficient photo-assisted electrocatalysis for methanol oxidation reaction(MOR)realizes the conversion of solar and chemical energy into electric energy simultaneously.Here we report a Pt-MXene-TiO2 composite for highly efficient MOR via a photoactive cascaded electro-catalytic process.With light(UV and visible light)irradiation,MXene-TiO2 serves as the photo active centre(photoinduced hole)to activate the methanol molecules,while Pt particles are the active centre for the following electro-catalytic oxidation of those activated methanol molecules.Pt-MXene-TiO2 catalyst exhibits a lower onset potential(0.33 V)and an impressive mass activity of 2,750.42 mA·mg^−1 Pt under light illumination.It represents the highest MOR activity ever reported for photo-assisted electrocatalysts.Pt-MXene-TiO2 also shows excellent CO tolerance ability and stability,in which,after long-term(5,000 s)reaction,still keeps a high mass activity of 1,269.81 mA·mg−1Pt(62.66%of its initial activity).The photo-electro-catalytic system proposed in this work offers novel opportunities for exploiting photo-assisted enhancement of highly efficient and stable catalysts for MOR.

Morphology optimization of photoactive layers in organic solar cells

Organic solar cells(OSCs)have unique advantages of light weight,low-cost solution processing,and capability to be fabricated into flexible and semitransparent devices,which are widely recognized as a promising photovoltaic technology.Photoactive layers of the OSCs are composed of a blend of a p-type organic semiconductor as a donor(D)and an n-type organic semiconductor as acceptor(A).The morphology of the active layer with D/A nano-scaled aggregation and face-onπconjugated packing,and D/A interpenetrating network is crucial for achieving high photovoltaic performance of the OSCs.Therefore,great efforts have been devoted to control and optimize morphology of the active layers.This perspective focuses on the morphological control by solvent/solid processing additives and the morphology optimization by postdeposition treatment with thermal annealing and/or solvent vapor annealing,which have been extensively adopted and exhibit promising positive effect in optimizing the morphology.Representative examples are given and discussed to understand the foundation of the postdeposition treatments on tuning the morphology.Insights into the role of the postdeposition treatments and additive treatments on the morphology optimization will be beneficial to further improvement in morphology optimization for practical organic photovoltaic application.

Preparation and Characterization of Novel Thermostable Polyamides Bearing Different Photoactive Pendent Architectures with Antibacterial Properties

Three diamine monomers with different derivatives of imidazole heterocyclic ring, aryl ethers and electron withdrawing trifluoromethyl groups in the backbone were synthesized and used in polycodensation reaction with various aliphatic and aromatic dicarboxylic acids for preparation of a series of novel polyamides （PAs）. The PAs were obtained in high yields and possessed inherent viscosities in the range of 0.26-0.75 dL/g. All of the polymers were amorphous in nature, showed outstanding solubility and could be easily dissolved in amide-type polar aprotic solvents. They showed good thermal stability with glass transition temperatures between 162-302 ℃. Thermogravimetric analysis showed that all polymers were stable, with 10% weight loss recorded above 421 ℃in N2 atmospheres. All the PAs presented fluorescence upon irradiation with ultraviolet light and thus showed promise for applications in electroluminescent devices. The monomers and PAs were also screened for antibacterial activity against Gram positive and Gram negative bacteria.

Photoactive Poly（aryl ether）s Containing Azobenzene Moieties on Pendants for Fabrication of Thermal Stable Surface Relief Gratings

A series of azobenzene functionalized poly（aryl ether） copolymers（azo-PAEs） containing azo moieties on pendants was prepared by direct copolymerization. The amount of azobenzene chromophores could be controlled by the feed ratio of azo-monomer. Their chemical structures and properties were characterized by means of infrared（IR） spectrometry, UV-Vis, hydrogen nuclear magnetic resonance（Ill NMR）, difference scanning calorimetry（DSC）, and thermogravimetric analysis（TGA）. The results suggest that azo-PAEs had high glass transition temperatures（Tgs） and good thermal stability. By exposing their spin-coated films to an interference pattern laser beam, azo-PAEs could be used for the fabrication of thermal stable surface relief gratings（SRGs）.

DESIGN AND STUDY OF NEW AZOBENZENE LIQUID CRYSTAL/POLYMER MATERIALS

Discussion is presented on the use of the photoisomerization of azobenzene chromophore in the design andpreparation of novel functional materials. The two systems reviewed are azobenzene polymer-stabilized liquid crystals andazobenzene elastomers. In the first case, a polymer network containing azobenzene moieties is used to optically induce andstabilize a long-range liquid crystal orientation without the need of treating the surfaces of the substrates. This optical andrubbing-free approach was applied to nematic and ferroelectric liquid crystals. In the second case, an azobenzene side-chainliquid crystalline polymer is grafted onto a styrene-butadiene-styrene triblock copolymer to yield a photoactive thermoplasticelastomer. Coupled mechanical and optical effects make possible the formation of dimaction gratings that may be useful formechanically tunable optical devices.

Damage threshold influenced by polishing imperfection distribution under 355-nm laser irradiation

A systematic interpretation of laser-induced damage in the nanosecond regime is realized with a defect distribution buried inside the redeposited layer arising from a polishing process. Under the 355-nm laser irradiation, the size dependence of the defect embedded in the fused silica can be illustrated through the thermal conduction model. Considering CeO2 as the major initiator, the size distribution with the power law model is determined from the damage probability statistics. To verify the accuracy of the size distribution, the ion output scaling with depth for the inclusion element is obtained with the secondary ion mass spectrometer. For CeO2 particulates in size of the depth interval with ion output satisfied in the negative exponential form, the corresponding density is consistent with that of the identical size in the calculated size distribution. This coincidence implies an alternative method for the density analysis of photoactive imperfections within optical components at the semi-quantitative level based on the laser damage tests.

Antimicrobial technology in orthopedic and spinal implants

Infections can hinder orthopedic implant function and retention.Current implant-based antimicrobial strategies largely utilize coating-based approaches in order to reduce biofilm formation and bacterial adhesion.Several emerging antimicrobial technologies that integrate a multidisciplinary combination of drug delivery systems,material science,immunology,and polymer chemistry are in development and early clinical use.This review outlines orthopedic implant antimicrobial technology,its current applications and supporting evidence,and clinically promising future directions.

Investigation on Lanthanum Fluoride as a Novel Cathode Buffer Material Layer for the Enhancement of Stability and Performance of Organic Solar Cell

This article presents the investigation on very thin Lanthanum Fluoride (LaF3) layer as a new cathode buffer layer (CBL) for organic solar cell (OSC). OSCs were fabricated with poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) polymer blend at 1:1 ratio. Electron-beam evaporation at room temperature was used to deposit 3 and 5 nm thick LaF3 layer. A very smooth surface of LaF3 with an average roughness of 0.2 nm has been observed by the Atomic Force Microscope (AFM) that is expected to prevent diffusion of cathode metal ion through it and thereby enhance the lifetime and stability of OSC. Huge enhancement of JSC and VOC was also observed for 3 nm-thick LaF3 CBL. Several excellent features of the LaF3 layer such as, transporting electron through tunneling, blocking of holes to the cathode, minimizing recombination, protecting the photoactive polymer from ambient oxygen, and reducing degradation/oxidation of any low work function layer at the cathode interface, might have contributed to the performance enhancement of OSC. The experimental findings indicate the promise of LaF3 to be an excellent CBL material for OSC.

Oxygen vacancies enable the visible light photoactivity of chromium-implanted TiO2 nanowires

Although computational studies have demonstrated that metal ion doping can effectively narrow the bandgap of TiO_(2),the visible-light photoactivity of metal-doped TiO_(2) photoanodes is still far from satisfactory.Herein,we report an effective strategy to activate the visible-light photoactivity of chromiumimplanted TiO_(2) via the incorporation of oxygen vacancies.The chromium-doped TiO_(2) activated by oxygen vacancies(Cr-TiO_(2)-vac)exhibited an incident photon-to-electron conversion efficiency(IPCE)of~6.8%at450 nm,which is one of the best values reported for metal-doped TiO_(2).Moreover,Cr-TiO_(2)-vac showed no obvious photocurrent decay after 100 h under visible-light illumination.

Synthesis and Photoinitiated Crosslinking of Active Poly(lactic acid) Materials

Acrylate-terminated poly（lactic acid）（DPLA） was synthesized by polycondensation, using lactic acid, polyalcohol and acrylic acid as the raw materials. The prepolymer products in each process were characterized by FT-IR, 1 H-NMR, GPC and DSC. DPLAs were then formulated with reactive diluent and diphenyl ketone as photoinitiator and photopolymerized into film（FPLA）. Thermal stability and degradation properties of the UV curing PLA film were studied. The results showed that the structures of prepolymer and the performances of the film could be adjusted by changing the types and content of the branching agent polyalcohol. After crosslinking modification, the degradation rate of FPLA was reduced and FPLA had better thermal stability than the pure PLA.

A strategy of enhancing the photoactivity of TiO_2 containing nonmetal and transition metal dopants

An effective structural codoping approach is proposed to modify the photoelectrochemical （PEC） properties of anatase TiO2 by being doped with nonmetal （N or/and C） and transition metal （Re） elements. The electronic structures and for- mation energies of different doped systems are investigated using spin-polarized density functional theory. We find that （C, Re） doped TiO2, with a low formation energy and a large binding energy, reduces the band gap to a large extent, thus it could contribute to the significant enhancement of the photocatalytic activity in the visible-light region. It should be pointed out that, to be successful, the proper proportion of the dopants C and Re should be controlled, so that reasonable PEC properties can be achieved.

Carbon quantum dots-based semiconductor preparation methods,applications and mechanisms in environmental contamination

Photocatalyst is the most widespread method in advanced oxidation technologies,but due to the photoinduced electron combine easily with hole and the wavele ngth of adsorption is limited which will affect some practical applications.Carbon quantum dots(CQDs)is non-toxic and harmless green materials,it has the ability to improve the photocatalytic effect which is attributed to its good electrical and optical properties.Their up-conversion effect,photosensitization and electrical conductivity are assistants which help promote the photocatalytic effect in environmental applications.The key mechanisms of CQDs to improve photocatalysis can be roughly divided into three categories:1)Up-conversion effect conve rts the incident light into the emitted light with high ene rgy to solve the problem which is the light absorption range;2)CQDs act as a photosensitizer instead of valence band to provide electrons to the conduction band of semiconductor;3)CQD s can be used as the internal or external electronic conductor in materials to alleviate the trend of electron and hole separation.However,CQDs and CQDs-based photocatalysts have different views to solve environmental problems,so it is necessary to integrate different views.Therefore,this review is mainly aimed at the recent researches about the preparation processes of CQD,CQD s-based photocatalysts,and their ability to remove environmental pollutants,with a special emphasis on the mechanism for depredating pollutants.Furthermore,this paper analyzes and discusses the prospects and challenges of CQDs in the environmental field.

Integrin-targeting with peptide-bioconjugated semiconductor-magnetic nanocrystalline heterostructures

Binary asymmetric nanocrystals （BNCs）, composed of a photoactive TiO2 nanorod joined with a superparamagnetic γ-Fe203 spherical domain, were embedded in polyethylene glycol modified phospholipid micelle and successfully bioconjugated to a suitably designed peptide containing an RGD motif. BNCs represent a relevant multifunctional nanomaterial, owing to the coexistence of two distinct domains in one particle, characterized by high photoactivity and magnetic properties, that is particularly suited for use as a phototherapy and hyperthermia agent as well as a magnetic probe in biological imaging. We selected the RGD motif in order to target integrin expressed on activated endothelial cells and several types of cancer cells. The prepared RGD-peptide/BNC conjugates, comprehensively monitored by using complementary optical and structural techniques, demon- strated a high stability and uniform dispersibility in biological media. The cytotoxicity of the RGD-peptide/BNC conjugates was studied in vitro. The cellular uptake of RGD-peptide conjugates in the cells, assessed by means of two distinct approaches, namely confocal microscopy analysis and emission spectroscopy determination in cell lysates, displayed selectivity of the RGD-peptide-BNC conjugate for the cw]33 integrin. These RGD-peptide-BNC conjugates have a high potential for theranostic treatment of cancer.

提高聚合物太阳电池性能的新方法:两步溶解法制备电池活性层（英文）

本文以P3HT:PC_(61)BM和PTB7:PC_(71)BM两种有机光伏体系为研究对象,探讨了光伏材料的"两步"溶解处理对聚合物太阳电池性能的影响.P3HT:PC_(61)BM光活性层的光学与形貌表征揭示了P3HT的有序相结构和给/受体相分离结构可以被"两步"溶解处理进一步优化;瞬态荧光数据表明,P3HT:PC_(61)BM光活性材料经"两步"溶解处理后,激子的分离能力得到增强.经"两步"溶解处理后的器件性能较"一步"溶解处理的器件性能提高了24%.此外,同样的处理方式应用于PTB7:PC_(71)BM体系,可使器件的光伏性能提高8%.因此,光活性材料的"两步"溶解处理是一种简单、有效的提高聚合物光伏性能的优化方法.