Choline chloride-based deep eutectic solvents as effective electrolytes for dye-sensitized solar cells

Electrolytes for dye-sensitized solar cells remain a challenge for large-scale production and commercialization, hindering the wide application of solar cells. We have developed two new electrolyte-based deep eutectic solvents using a mixture of choline chloride with urea and with ethylene glycol for dye-sensitized solar cells. The prominent features of the two deep eutectic solvent electrolytes are simple preparation for large-scale production with inexpensive, available, and nontoxic starting materials and biodegradability. The solar cell devices proceeded in a safe manner as the two deep eutectic solvents afforded low-cost technology and comparative conversion efficiency to a popular ionic liquid, namely 1-ethyl-3-methylimidazolium tetracyanoborate. Results showed that devices with choline chloride and urea electrolyte exhibited improved open circuit voltage values (V_OC), while the ones with choline chloride and ethylene glycol showed an increase in the short circuit current (I_sc). Characterization of the devices by electrochemical impedance spectroscopy helped explain the effects of their molecular structures on the enhancement of either V_OC or I_sc values. These new solvents expand the electrolyte choices for designing dye-sensitized solar cells, especially for the purpose of using low-cost and eco-friendly materials for massive production.

Electrolytes for dye-sensitized solar cells remain a challenge for large-scale production and commercialization, hindering the wide application of solar cells.     

Novel 2D-AuSe nanostructures as effective platinum replacement counter electrodes in dye-sensitized solar cells

Studies to improve the efficiency of dye-sensitized solar cells (DSSCs) include, but are not limited to, finding alternatives such as 2D layered materials as replacement counter electrodes (CEs) to the commonly used Pt. Herein, we report for the first time, the use of AuSe as a counter electrode for the reduction of triiodide ions (I₃⁻) to iodide ions (I⁻). The colloidal synthesis of gold selenide nanostructures produced α-AuSe and β-AuSe dominated products as determined by XRD. Electron microscopy showed α-AuSe having belt-like structures while β-AuSe had a plate-like morphology. EDS mapping confirmed the elemental composition and homogeneity of the AuSe CEs. Cyclic voltammetry curves of the AuSe CEs displayed the double set of reduction–oxidation peaks associated with the reactions in the I₃⁻/I⁻ electrolyte and therefore were comparable to the Pt CV curve. The α-AuSe CE showed better electrocatalytic activity with a reduction current of 6.1 mA than that of β-AuSe and Pt CEs, which were 4.2 mA and 4.8 mA, respectively. The peak-to-peak separation (ΔE_pp) for the α-AuSe CE was also more favourable with a value of 532 mV over that of the β-AuSe CE of 739 mV however, both values were larger than that of the Pt CE, which was found to be 468 mV. The EIS and Tafel plot data showed that α-AuSe had the best catalytic activity compared to β-AuSe and was comparable to Pt. The DSSC using α-AuSe as a CE had the highest PCE (6.94%) as compared to Pt (4.89%) and β-AuSe (3.47%). The lower efficiency for Pt was attributed to the poorer fill factor. With these novel results, α-AuSe is an excellent candidate to be used as an alternative CE to Pt in DSSCs.

Studies to improve the efficiency of dye-sensitized solar cells (DSSCs) include, but are not limited to, finding alternatives such as 2D layered materials as replacement counter electrodes (CEs) to the commonly used Pt.     

Hierarchical TiO2 microspheres composed with nanoparticle-decorated nanorods for the enhanced photovoltaic performance in dye-sensitized solar cells

Hierarchical TiO₂ microspheres composed of nanoparticle-decorated nanorods (NP-MS) were successfully prepared with a two-step solvothermal method. There were three benefits associated with the use of NP-MS as a photoanode material. The decoration of nanoparticles improved the specific surface area and directly enhanced the dye loading ability. Rutile nanorods serving as electron transport paths resulted in fast electron transport and inhibited the charge recombination process. The three-dimensional hierarchical NP-MS structure supplied a strong light scattering capability and good connectivity. Thus, the hierarchical NP-MS combined the beneficial properties of improved scattering capability, dye loading ability, electron transport and inhibited charge recombination. Attributed to these advantages, a photoelectric conversion efficiency of up to 7.32% was obtained with the NP-MS film-based photoanode, resulting in a 43.5% enhancement compared to the efficiency of the P25 film-based photoanode (5.10%) at a similar thickness. Compared to traditional photoanodes with scattering layers or scattering centers, the fabrication process for single layered photoanodes with enhanced scattering capability was very simple. We believe the strategy would be beneficial for the easy fabrication of efficient dye-sensitized solar cells.

Hierarchical NP-MS combines the beneficial properties of improved scattering capability, dye loading ability, electron transport and inhibited charge recombination. The photoelectric conversion efficiency up to 7.32% has been obtained.     

Coaxial heterojunction carbon nanofibers with charge transport and electrocatalytic reduction phases for high performance dye-sensitized solar cells

Novel coaxial heterojunction carbon nanofibers, fabricated by electro-spinning a mixture of hydro-pitch and polyacrylonitrile, served as the counter electrode for dye-sensitized solar cells. Their high power conversion efficiency, being comparable to that of Pt CE, was achieved due to their good conductivity and high heteroatom content.

Coaxial CNFs featured high conductivity derived from HP, and high N content and defective sites derived from PAN.

The counter electrode (CE) in dye-sensitized solar cells (DSSCs) has multiple functions, including the catalytic reduction of I₃⁻ to I⁻ and the regeneration of dye molecules, and is one of the key dominant components that governs the practical applications of DSSCs to a great degree.¹ Noble metal platinum (Pt) with its low electrical resistance and excellent electrocatalytic activity was the first to be applied as such and is now widely used as CEs in DSSCs. However, there is limited availability of Pt sources, and this has led to the high cost of CEs, which has hindered the practical applications of DSSCs.² To date, various efforts have been made to develop techniques for the production of inexpensive yet high performance CEs to replace the Pt CEs. Of the alternatives now available, carbon materials that are categorized as zero-dimensional (0D) to three-dimensional (3D) structures have attracted much attention as candidates for Pt-free electrodes in view of the advantages of low cost as well as good electrochemical stability; these include carbon black,³ carbon nanoparticles,⁴ carbon nanotubes,^5–9 graphene,^10–14 and graphite¹⁵ and their composites.^16–19 It is believed that a large quantity of defects in the carbon CEs may lead to high catalytic activities, while good electric conductivity can result in fast charge transportation. Nevertheless, how to combine and integrate the high electrical conductivity and abundant defects into one carbon electrode in a balanced way to fabricate high performance CEs with tuned structure remains a major challenge.Recently, one dimensional (1D) core–shell nanofibers have received much attention because a good combination of electrical conductivity and catalytic activity can be realized and achieved in one electrode material.²⁰ However, the core and shell in these fibers are two separate phases, which limits the rapid charge transition and increases the electrical resistance when such nanofibers are used as CEs in DSSCs. Moreover, the tedious and complicated fabrication process greatly limits their large-scale production. As such, it is necessary to explore a new approach for this kind of material, in which electrical conductivity and catalytic activity are combined well.Herein, we present 1D coaxial carbon nanofibers (CNFs) fabricated by the electrospinning method from two kinds of carbon precursors: hydrogenated pitch and polyacrylonitrile (PAN). The adopted hydro-pitch (HP) features planar aromatic hydrocarbon molecules and is more easily transformed into an optically anisotropic, graphitizable carbon structure,²¹ thus leading to high conductivity (Table S1, ESI^†). PAN tends to form a carbonaceous structure with high nitrogen (N) content and abundant defects; it is widely acknowledged that high electrochemical activities could be achieved by the different nitrogen species and defects.^{7,16,17,22–24} Benefiting from different nucleation mechanisms, a novel coaxial core/shell structure has been produced within the matrix, in which hydro-pitch contributes to the core phase, while PAN is responsible for the shell phase. Such CNFs with two phases and heterogeneous characteristics are very unique when they are applied as CEs in DSSCs, with the core playing the role of cable tunnel for charge transporting and the shell providing active sites for catalyzing the reduction of I₃⁻ to I⁻, as shown in Scheme 1.Open in a separate windowScheme 1Illustration of the structure and functions of heterojunction carbon nanofibers as CEs in DSSCs.The process of fabricating our CNFs (denoted as 0.15-HCNF and 1-HCNF, in which 0.15 and 1 are the weight ratios between hydro-pitch and PAN) is illustrated in Fig. S5,^† and the morphologies of different CNFs and their corresponding diameter distributions are shown in Fig. 1a–c and a₁–c₁. The average diameter is 0.33 μm for PAN CNFs (PCNF), 0.36 μm for 0.15-HCNF, and 0.76 μm for 1-HCNF, indicative of a size-increased behavior with the increase in the ratio between the hydro-pitch and PAN. The obtained CNFs in sample 1-HCNF are cross-linked or joined together, as can be seen in Fig. 1c, leading to the inner parts being exposed and the observation of different phases.Open in a separate windowFig. 1Scanning electron microscopy (SEM) images of (a) PCNF, (b) 0.15-HCNF and (c) 1-HCNF.The HCNFs were examined in much detail by transmission electron microscopy (TEM) to yield information about the inner structure, and the typical TEM images are shown in Fig. 2. It can be clearly seen that two phases in the axial direction are obviously observed in the HCNF samples (Fig. 2b and c) in comparison to PCNF (Fig. 2a). Energy-dispersive X-ray spectra (EDX) of the shell region show the high nitrogen content of 9.3 at% (Fig. 2e), which implies that the carbon shell is derived from PAN. To further gain insight into the contributions of these two precursors, sample 1-HCNF was treated with KOH at high temperature to remove the shell, and the corresponding sample was further characterized by TEM and EDX, the detailed results of which are shown in Fig. 2d and f. It can be seen that the shell layer was removed, and the content of nitrogen was only 1 at% in the core phase (Table S2, ESI^†), in comparison to there being only 0.4 wt% (Table S3, ESI^†) of nitrogen in the hydro-pitch.Open in a separate windowFig. 2TEM images of (a) PCNF, (b) 0.15-HCNF, (c) 1-HCNF, and (d) the core of the 1-HCNF fiber after KOH treatment for 1 h at 700 °C in N₂. (e and f) The EDX spectra of the fiber shell and core.With all of this information in mind, it was deduced that the core phase was mainly derived from the hydro-pitch, while the shell was mainly from PAN.It is interesting that this result is different from that reported by Yang.²⁵ In general, the low molecular weight pitch tends to be pushed to the outer surface during the solvent evaporation process.^26,27 Nevertheless, in the present system the hydro-pitch is more easily fixed in the inner part, which was evidenced by density functional theory (DFT) calculations (Fig. 3). As shown in Fig. 3a, the binding energy between the hydro-pitch and two PAN units (E_HP) is 5.6 kcal mol⁻¹, which is 1.3 kcal mol⁻¹ higher than that between pitch and PAN units (E_P, 4.3 kcal mol⁻¹). When three PAN units were applied, an increase of 25% was observed for E_HP, which reached 7.0 kcal mol⁻¹. The newly formed hydrogen bonding between aliphatic hydrogen in hydro-pitch and the cyano group in the PAN unit is responsible for the remarkable increase in binding energy, while the number of E_P only slightly increased from 4.3 to 4.4 kcal mol⁻¹, and no new bonding was observed. As a result, compared to the pitch, the hydro-pitch could be more easily fixed in PAN units due to the strong binding caused by the multi-interaction between the aliphatic hydrogen and cyano groups. In addition, the hydro-pitch is always wrapped by several PAN long chain molecules, as shown in Fig. S5.^† Therefore, a kind of heterojunction core–shell structure was finally produced, in which the core was attributed to the hydro-pitch while the shell was attributed to PAN.Open in a separate windowFig. 3The spatial configurations and binding energies between two kinds of pitch molecules and PAN units. (a) Hydro-pitch with two PAN units, (b) molecular pitch and two PAN units, (c) hydro-pitch and three PAN units, (d) molecular pitch and three PAN units.The HCNF samples were also analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectra to reveal the changes in the surface configuration caused by the addition of hydro-pitch (Fig. S2, ESI^†). Compared to PCNF (7.6 at%, Table S4, ESI^†), sample 0.15-HCNF maintained 4.6 at% nitrogen content, and the same I_D/I_G ratio (1.07) was also obtained for the two samples. With an increase in hydro-pitch in the case of 1-HCNF, a slightly lower nitrogen content (4.2 at%) and I_D/I_G number (1.01) were observed, which could be attributed to the exposure of the hydro-pitch-based core, as mentioned in Fig. 1c. The XPS spectrum of N 1s is shown in Fig. S3 in the ESI^† and the ratios of different nitrogen species are summarized in Table S5.^† It is well known that these nitrogen species in the carbon network could produce highly electrocatalytically active sites,^22,23 while the defects in carbon materials could also play the same role.The HCNFs exhibited unique characteristics in which the shell retained the high nitrogen content and defects, while the core derived from hydro-pitch featured high conductivity. Such an integrated structure in one electrode is so attractive that it could be used as a high-performance CE in DSSCs, as shown in Scheme 1. In this case, it has great potential as an electrocatalyst for Pt replacement in DSSCs. Benefiting from this, the device performance for DSSCs with PCNF, Pt, and two HCNF CEs was determined and the results are shown in

Improved performance of dye-sensitized solar cells upon sintering of a PEDOT cathode at various temperatures

Poly(3,4-ethylenedioxythiophene) (PEDOT) thin films have attracted considerable attention as cathodes for dye-sensitized solar cells (DSSCs) due to their air-stable, light-weight and conductive nature. To demonstrate their thermal stability as cathodes, PEDOT thin films coated via electrochemical polymerization on fluorine doped tin oxide (FTO) plates were sintered at different temperatures (50, 100, 150, 200, and 300 °C) for 1 h and a comparison was made with the as-prepared PEDOT thin films. We observed a negative temperature coefficient effect up to 200 °C along with lower surface roughness upon increasing the sintering temperature. Dye solar cells were fabricated using PEDOT thin films (sintered at different temperatures) and as-prepared PEDOT cathodes, and their respective performances were studied. The results showed increased efficiency with the increase in sintering temperatures of the cathode up to 200 °C (η = 4.33%) under the present experimental conditions. Cathodes sintered at 300 °C had poor electrochemical behavior and J–V performance, which may be due to polymer degradation.

Poly(3,4-ethylenedioxythiophene) (PEDOT) thin films have attracted considerable attention as cathodes for dye-sensitized solar cells (DSSCs) due to their air-stable, light-weight and conductive nature.     

Efficient azobenzene co-sensitizer for wide spectral absorption of dye-sensitized solar cells

Two azobenzene dyes, [Cu(azobenzene-4,4′-dicarboxylate) diethylenediamine]_n (ADD), [Cd(4,4′-diazenediyldibenzoato)(H₂O)]_n (DDB), have been designed, synthesized, and characterized as efficient co-sensitizers for dye-sensitized solar cells (DSSC). The optical, charge-transfer, electrochemical and photovoltaic properties of ADD and DDB are investigated by UV-visible spectroscopy, transient surface photovoltage measurement, cyclic voltammetry, and photocurrent–photovoltage measurement. The combination of ADD and DDB in DSSC leads to a wide spectral absorption over the whole visible range (350–700 nm). DSSC with ADD and DDB exhibits a short-circuit photocurrent density as high as 16.96 mA cm⁻², open-circuit photovoltage of 0.73 V, a fill factor of 0.57, and overall light conversion efficiency of 7.1% under standard global AM1.5 solar irradiation conditions.

The combination of two azobenzene dyes leads to a wide spectral absorption and overall light conversion efficiency of 7.1%.     

Optimization of 3D ZnO brush-like nanorods for dye-sensitized solar cells

In a dye-sensitized solar cell (DSSC) the amount of adsorbed dye on the photoanode surface is a key factor that must be maximized in order to obtain enhanced DSSC performance. In this study 3D ZnO nanostructures, named brush-like, are demonstrated as alternative photoanodes. In these structures, long ZnO nanorods are covered with a metal–organic precursor, known as a layered-hydroxide zinc salt (LHZS), which is subsequently converted to crystalline ZnO using two-step annealing. The LHZS is able to easily grow on any surface, such as the ZnO nanorod surface, without needing the assistance of a seed-layer. Brush-like structures synthesized using different citrate concentrations in the growth solutions and different annealing conditions are characterized and tested as DSSC photoanodes. The best-performing structure reported in this study was obtained using the highest citrate concentration (1.808 mM) and the lowest temperature annealing condition in an oxidative environment. Conversion efficiency as high as 1.95% was obtained when these brush-like structures were employed as DSSC photoanodes. These results are extremely promising for the implementation of these innovative structures in enhanced DSSCs, as well as in other applications that require the maximization of surface area exposed by ZnO or similar semiconductors, such as gas- or bio-sensing or photocatalysis.

Optimized 3D ZnO brush-like nanorods showing large surface area are presented as the photoanode in enhanced high-current-density DSSCs.     

Model systems for dye-sensitized solar cells: cyanidin-silver nanocluster hybrids at TiO2 support

Theoretical study of structural, optical, and photovoltaic properties of novel bio-nano hybrids (dye-nanocluster), as well as at TiO₂ surface model support is presented in the context of the application for dye-sensitized solar cells (DSSC). A group of anthocyanidin dyes (pelargonidin, cyanidin, delphinidin, peonidin, petunidin, and malvidin) represented by cyanidin covalently bound to silver nanoclusters (NCs) with even or odd number of valence electrons have been investigated using DFT and TDDFT approach. The key role of nanoclusters as acceptors in hybrids cyanidin-NC has been shown. The nanoclusters with an even number of valence electrons are suitable as acceptors in hybrids. The interaction of bio-nano (cyanidin-NC) hybrid with the TiO₂ surface model has been investigated in the context of absorption in near-infrared (NIR) and charge separation due to donor and acceptor subunits. Altogether, the theoretical concept serves to identify the key steps in the design of novel solar cells based on bio-nano hybrids at TiO₂ surface for DSSC application.

The theoretical concept of this paper serves to identify the key steps in the design of novel solar cells based on bio-nano hybrids (cyanidin-Ag_n) on a TiO₂ surface for possible DSSC application.     

ANTT: an essential tool for effective blood culture collection

Blood culture collection is an important and topical intravenous procedure for the management of suspected infection. Contaminated samples can lead to 'false positive' results, and inappropriate clinical interventions, which can compromise patient outcome and incur significant expense to healthcare organizations. The contamination of blood culture samples by ineffective aseptic technique has been estimated to be as high as 10% (Department of Health (DH), 2007a). Aseptic Non Touch Technique (ANTT) is a ground-breaking global initiative designed to improve outcomes of aseptic technique through the rationalization and standardization of practice. The ANTT blood culture collection guideline provides nationally peer-reviewed guidance on safe and efficient blood sampling for laboratory culture. The guideline complements the DH's (2007a) Saving Lives summary of best practice for taking blood cultures, providing health professionals with a standardized method of complying with best practice guidance from the epic project (Pratt et al, 2007).     

The coaching process: an effective tool for professional development

A model for coaching in nursing is described. Criteria for selecting a coach are discussed. Competencies for a coach are recommended. In addition, guidelines for caching sessions are provided as well as an example of an action plan outline to help the coachee identify areas of desired growth and options for developing these areas.     

UV-selective organic absorbers for the cosensitization of greenhouse-integrated dye-sensitized solar cells: synthesis and computational study

Molecular cosensitization is favorable for manipulating solar radiation through the judicious choice of cosensitizers having complementary absorption spectra. For greenhouse-integrated dye-sensitized solar cells (DSCs), the manipulation of solar radiation is crucial in order to maximize the flow of photosynthetically active radiation (PAR) for the effectual photosynthetic activity of plants; meanwhile, non-PAR is utilized in agrivoltaics for generating electricity. In this study, we report the synthesis of novel four UV-selective absorbers, based on the diimide scaffold, functionalized with carboxylate and pyridyl anchoring groups, for adequate adsorption onto the TiO₂ electrode in DSC. The UV/Vis absorption spectra of the DMF solution-based free dyes were measured experimentally. Basic photophysical and energetics requirements for operating greenhouse-integrated DSCs were examined at the molecular level via (time-dependent) density functional theory-based calculations. The computational results revealed the outperformance of the biphenyldiimide-structured DI-CA1 dye, especially for maximum charge transferred to its anchor, lower thermodynamic barrier for dissociating the photogenerated exciton, largest Stokes'' shift, strong electronic coupling with TiO₂ nanoparticles, and higher degree of charge separation at the DI-CA1/TiO₂ interface. PDOS showed deeper existence for the LUMO level in the CB of TiO₂, which expedites the electron injection process. The chemical and optical compatibility of DI-CA1 were then investigated as a potential cosensitizer of a reference BTD–DTP1, a green light-absorbing dye. Considerable overlap between the fluorescence spectrum of DI-CA1 and absorption spectrum of the reference BTD–DTP1 advocated the opportunity of excitation energy transfer via the radiative trivial reabsorption mechanism, which confirms the cosensitization functionality. Energy decomposition analysis and reduced density gradient maps estimated the chemical compatibility owing to weak dispersion interactions as the dominant stabilizing attractive force. This noncovalent functionalization retains the chemical compatibility without distorting the π–π conjugation and the associated physicochemical properties of the individual dye molecules. Along with the expanded consumption of non-photosynthetically active solar radiation, an improved power conversion efficiency of greenhouse-integrated DSC is accordingly expected.

Molecular cosensitization is favorable for manipulating solar radiation through the judicious choice of cosensitizers having complementary absorption spectra.     

Functionalized carboxylate deposition of triphenylamine-based organic dyes for efficient dye-sensitized solar cells

The standard dip-coating dye-loading technique for dye-sensitized solar cells (DSSCs) remains essentially unchanged since modern DSSCs were introduced in 1991. This technique constitutes up to 80% of the DSSC fabrication time. Dip-coating of DSSC dyes not only costs time, but also generates a large amount of dye waste, necessitates use of organic solvents, requires sensitization under dark conditions, and often results in inefficient sensitization. Functionalized Carboxylate Deposition (FCD) was introduced as an alternative dye deposition technique, requiring only 2% of the fabrication time, eliminating the need for solvents, and significantly reducing dye waste. In this study, FCD was used to deposit two relatively large triphenylamine-based organic dyes (L1 and L2). These dyes were sublimated and deposited in <20 minutes via a customized FCD instrument using a vacuum of ∼0.1 mTorr and temperatures ≤280 °C. FCD-based DSSCs showed better efficiency (i.e., 5.03% and 5.46% for L1 and L2 dyes, respectively) compared to dip-coating (i.e., 4.36% and 5.35% for L1 and L2, respectively) in a fraction of the deposition time. With multiple advantages over dip-coating, FCD was shown to be a viable alternative for future ultra-low cost DSSC production.

Functionalized carboxylate deposition involves deposition of molecules from the gas phase and is an alternative dye loading technique to dip-coating. It was used to create a monolayer of large molecular weight dyes on TiO₂, providing multiple advantages to dip-coating.     

Efficient tuning of zinc phthalocyanine-based dyes for dye-sensitized solar cells: a detailed DFT study

The growing energy demand speed up the designing of competent photovoltaic materials. Herein, five zinc phthalocyanine-based donor materials T1–T5 are designed by substituting various groups (isopropoxy, cyano, fluoro, methoxycarbonyl, and dicyanomethyl) around zinc phthalocyanine. B3LYP/6-31G (d,p) level density functional theory (DFT) was used to investigate the optoelectronic properties of five zinc phthalocyanine-based dyes T1–T5 for dye-sensitized solar cells. The designed molecule T1 shows maximum absorption wavelength (λ_max) in the absorption spectrum at 708.89 and 751.88 nm both in gaseous state and in THF (tetrahydrofuran) solvent. The E_g value of T1 (1.86 eV) is less than reference R, indicating a greater charge transfer rate for T1 among the molecules. The values of open-circuit voltages achieved with acceptor polymer PC₇₁BM are higher than R except for T1 and are 0.69 V, 1.95 V, 1.20 V, 1.44 V, and 1.84 V for T1, T2, T3, T4, and T5, respectively. The lower the reorganization energy, the higher the charge transfer for T1 due to its lower hole mobility (0.06297 eV) than R. Thus, the designed T1–T5 molecules are expected to exhibit superior performance in dye-sensitized solar cells.

We used a quantum chemical approach to investigate the optoelectronic properties of dyes T1–T5 for dye-sensitized solar cells using DFT and TD-DFT computation. The newly designed molecules exhibited outstanding photovoltaic and optoelectronic properties.     

The Internet: an effective tool for nursing research with women

This article outlines the methodology of using the Internet to survey an international population of women about their perceptions of breast health education and screening. Issues to consider in planning and implementing the research project by Internet are presented. A large population of women from North America and elsewhere was reached through the establishment of a website with linkages to other sites frequented by women. Women who visited the website were asked to complete a questionnaire. Anonymity was guaranteed and simple instructions were provided at the site. Benefits, limitations, and tips for success in using the Internet as a research tool are presented. These investigators found the Internet to be an appropriate medium for health-related research that also garnered national and international media interest. The address for this website is http:@www.uwindsor.ca/breast.study/quest.htm.     

Synthesis,properties and photovoltaic performance in dye-sensitized solar cells of three meso-diphenylbacteriochlorins bearing a dual-function electron-donor

Bacteriochlorins are crucial to photosynthesis in bacteria. Studies of air-stable, meso-substituted bacteriochlorins are rare. We herein report the synthesis, properties, and photovoltaic performance of three new air-stable, meso-substituted bacteriochlorins bearing a dioctylfluorenylethyne (denoted as LS-17), a dioctylaminophenylethynylanthrylethyne (LS-43), and a diarylaminoanthrylethyne (LS-45) as the electron-donating groups. Among these LS-bacteriochlorins, LS-17 displays sharp UV-visible absorption bands whereas LS-43 and LS-45 give rise to broadened and red-shifted absorptions. Electrochemical and DFT results suggest that the first oxidation and reduction reactions of these bacteriochlorins are consistent with the formation of the cation and anion radicals, respectively. For dye-sensitized solar cell applications, photovoltaic performance of the LS-45 cell achieves an overall efficiency of 6.04% under one-sun irradiation.

Synthesis, properties, and photovoltaic performance of three new air-stable, meso-biphenylbacteriochlorins bearing a dual-function donor are reported.     

ZnO nanowire embedded TiO2 film as an electrode for perovskite CsPbI2Br solar cells

A comparative study was conducted to look into the impact of various electron transporting films on the performance of perovskite CsPbI₂Br solar cells. The solar cells with ZnO nanowires embedded TiO₂ as an electrode outperformed those with pure TiO₂ or pure ZnO. The enhanced performance is ascribed to the synergetic effect of both TiO₂/ZnO constituent properties. In particular, an appropriate amount of ZnO nanowires embedded in TiO₂ films could optimize the properties of the electron transporting layer by improving electron transport, light harvesting, and overall photovoltaic performance, leading to the power conversion efficiency as high as 10.53%.

A comparative study was conducted to look into the impact of various electron transporting films on the performance of perovskite CsPbI₂Br solar cells.     

Telemetry glucose monitoring device with needle-type glucose sensor: a useful tool for blood glucose monitoring in diabetic individuals

For continuous monitoring of glucose concentration in ambulant diabetic patients, a telemetry glucose monitoring system with a needle-type glucose sensor has been developed. The system consists of a sensor transmitter (4 X 6 X 2 cm, 50 g) that converts current signals generated in a needle-type glucose sensor to high-frequency audio signals and a receiver that continuously calculates glucose concentrations from the received audio signals. The noise range of a monitoring record with the telemetry system (0.3 +/- 0.04%, mean +/- SEM) was significantly smaller than that with a wire-connected system, the wearable artificial endocrine pancreas (2.5 +/- 0.3%). Postprandial tissue glucose concentration responded well to the plasma glucose concentration, with a time lag of 5 min. Continuous glucose monitoring of five diabetic subjects for 77 +/- 22 h revealed that a significant correlation existed between the subcutaneous tissue glucose concentration and the plasma glucose concentration measured simultaneously in each patient. These data indicate the usefulness of the telemetry glucose monitoring system in strict glycemic control of diabetic individuals.