Read by QxMD icon Read


Valeria Saavedra Becerril, Elin Sundin, Mokhtar Mapar, Maria Abrahamsson
A simple method for the preparation of patterned dye-sensitized SnO2-TiO2 thin films, designed to prolong the lifetime of the interfacial charge separated state is presented. Using microfluidic technology, the thin films were sensitized with the organic sensitizer D35 such that they contain SnO2-TiO2 areas with dye and SnO2 dye-free areas at which injected electrons can be accumulated. Single wavelength transient absorption spectroscopy confirmed significantly extended charge separation lifetime at the dye-semiconductor interface...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
Degao Wang, Matthew V Sheridan, Bing Shan, Byron H Farnum, Seth L Marquard, Benjamin D Sherman, Michael S Eberhart, Animesh Nayak, Christopher Dares, Atanu Das, R Morris Bullock, Thomas J Meyer
In a Dye Sensitized Photoelectrosynthesis Cell (DSPEC) the relative orientation of the catalyst and chromophore plays an important role in determining the device efficiency. Here we introduce a new, robust atomic layer deposition (ALD) procedure for the preparation of molecular chromophore-catalyst assemblies on wide bandgap semiconductors. In this procedure, solution deposited, phosphonate derivatized metal complexes on metal oxide surfaces are treated with reactive metal reagents in the gas phase by ALD to form an outer metal ion bridging group which can bind a second phosphonate containing species from solution to establish a R1-PO2-O-M-O-PO2-R2 type surface assembly...
August 15, 2017: Journal of the American Chemical Society
Surendra K Yadav, Sandheep Ravishankar, Sara Pescetelli, Antonio Agresti, Francisco Fabregat-Santiago, Aldo Di Carlo
In the last few decades, dye-sensitized solar cell (DSC) technology has been demonstrated to be a promising candidate for low cost energy production due to cost-effective materials and fabrication processes. Arguably, DSC stability is the biggest challenge for making this technology appealing for industrial exploitation. This work provides further insight into the stability of DSCs by considering specific dye-electrolyte systems characterized by Raman and impedance spectroscopy analysis. In particular, two ruthenium-based dyes, Z907 and Ru505, and two commercially available electrolytes, namely, the high stability electrolyte (HSE) and solvent-free Livion 12 (L-12), were tested...
August 15, 2017: Physical Chemistry Chemical Physics: PCCP
Xiaolei Wang, Peng Li, Xiao Xia Han, Yasutaka Kitahama, Bing Zhao, Yukihiro Ozaki
A number of recent studies have focused on improving the performance of dye-sensitized solar cells (DSSCs). Cells with a ZnO-TiO2/N3/Ag structure have attracted particular attention because of their excellent power conversion efficiencies. Using a dendritic crystal ZnO-TiO2 composite semiconductor and Ag in conjunction leads to different charge-transfer (CT) processes, and this is the main theoretical basis for the improvement of DSSC performances. Thus, in the present study, TiO2/N3, ZnO/N3, ZnO-TiO2/N3, TiO2/N3/Ag, ZnO/N3/Ag, and ZnO-TiO2/N3/Ag assemblies have been fabricated and their CT processes have been monitored by using surface-enhanced Raman scattering (SERS) spectra, with particular focus on the differences caused by the synergistic effect of the ZnO-TiO2 component...
August 14, 2017: Nanoscale
Mannix Padayhag Balanay, Dong Hee Kim
Bacteriochlorin-based dyes, having a push-pull type of configuration similar to the YD2 dye, were theoretically designed based on the modification of the macrocycle and π-conjugated bridge for use in dye-sensitized solar cells. Various parameters were assessed to determine its structure-property relationships, such as the absorption profile based on time-dependent density functional theory, non-linear optical properties from (hyper)polarizability data, ground- and excited-state oxidation potentials, and the electronic properties of the free and adsorbed dyes...
August 11, 2017: Journal of Physical Chemistry. A
Chihyun Park, Jongbeom Na, Eunkyoung Kim
Cross stacking of nanopatterned conductive polymer film was explored using a sacrificial soft template made of nanopatterned polystyrene (PS) film as a guide for nanopatterned conductive polymer film. For use as a conductive film, the PS pattern was filled with poly(3,4-ethylenedioxythiophene) (PEDOT), and then completely removed, to generate single-patterned PEDOT (SPDOT) film having a conductivity of 1079 S/cm, which was comparable to the pristine unpatterned PEDOT (UPDOT) film on a glass slide. SPDOT layers were stacked across each other to form double-layered (DPDOT) and multiple-layered patterned PEDOT film on a glass slide or polymeric substrate...
August 11, 2017: ACS Applied Materials & Interfaces
Hong Wang, Yi Hu, Shivaraj Yellappa, Michael B Thomas, R G Waruna Jinadasa, Alex Matus, Max Shulman, Francis D'souza
A novel class of β-functionalized push-pull zinc opp-dibenzoporphyrins were designed, synthesized and utilized as sensitizers for dye-sensitized solar cells. Spectral, electrochemical and computational studies were systematically performed to evaluate their spectral coverage, redox behavior and electronic structures. These porphyrins displayed much broader spectral coverage and more facile oxidation upon extension of π-conjugation. Free-energy calculations and femtosecond transient absorption studies (charge injection rate in the range of 1011 s-1) suggest efficient charge injection from the excited singlet state of porphyrin to the conduction band of the TiO2...
August 11, 2017: Chemistry, An Asian Journal
M M Maitani, K Tanaka, Q Shen, T Toyoda, Y Wada
Dye-sensitized solar cells (DSSCs) with reactive {001} facet-dominant TiO2 have attracted a great deal of attention owing to their high solar cell performance, despite the origin and the variation of the results being controversial. Here, we report the characteristic charge transport properties of DSSCs composed of {001} and {101} facet-dominant TiO2 nanoparticles in order to explain the origin of solar cell performance. Based on transient photocurrent and photovoltage measurements and transient absorption spectroscopy, the energetics of TiO2 semiconductors and dye sensitizers are utilized to understand the electron diffusion, recombination, and injection kinetics to determine solar cell performance...
August 10, 2017: Physical Chemistry Chemical Physics: PCCP
Phillip Brogdon, Hammad Cheema, Jared Heath Delcamp
We report four NIR photosensitizers employing a low-recombination donor and a thieno[3,4-b]thiophene (3,4-TT) π-bridge for use in dye-sensitized solar cells. The inclusion of electron rich π-spacers red-shifts the dye absorbance with solution absorption onsets reaching 700 nm. Dyes were found to have suitable energy levels for rapid electron transfers via cyclic voltammetry and UV-Vis-NIR absorption spectroscopy. Computationally optimized ground-state geometries show an increased torsional angle between π-spacer and π-bridge brought about by an added alkyl chain resulting in a widened optical band gap and increased oxidation potentials due to a weakening of the electron accepting ability of 3,4-TT for solution measurements...
August 8, 2017: ChemSusChem
Chaofan Sun, Yuanzuo Li, Peng Song, Fengcai Ma
The photoelectrical properties of two dyes-ethyl red and carminic acid-as sensitizers of dye-sensitized solar cells were investigated in experiments herein described. In order to reveal the reason for the difference between the photoelectrical properties of the two dyes, the ground state and excited state properties of the dyes before and after adsorbed on TiO₂ were calculated via density functional theory (DFT) and time-dependent DFT (TDDFT). The key parameters including the light harvesting efficiency (LHE), the driving force of electron injection ( Δ G inject ) and dye regeneration ( Δ G regen ), the total dipole moment ( μ normal ), the conduction band of edge of the semiconductor ( Δ E CB ), and the excited state lifetime (τ) were investigated, which are closely related to the short-circuit current density ( J sc ) and open circuit voltage ( V oc )...
October 1, 2016: Materials
Chung-Yi Wu, Kuan-Ju Tu, Jin-Pei Deng, Yu-Shiu Lo, Chien-Hou Wu
The benefits of increasing the number of surface hydroxyls on TiO₂ nanoparticles (NPs) are known for environmental and energy applications; however, the roles of the hydroxyl groups have not been characterized and distinguished. Herein, TiO₂ NPs with abundant surface hydroxyl groups were prepared using commercial titanium dioxide (ST-01) powder pretreated with alkaline hydrogen peroxide. Through this simple treatment, the pure anatase phase was retained with an average crystallite size of 5 nm and the surface hydroxyl group density was enhanced to 12...
May 22, 2017: Materials
Jenn-Kai Tsai, Yu-Shin Tu
In this study, high energy conversion efficient dye-sensitized solar cells (DSSCs) were successfully fabricated by attaching a double anti-reflection (AR) layer, which is composed of a subwavelength moth-eye structured polymethyl methacrylate (PMMA) film and a polydimethylsiloxane (PDMS) film. An efficiency of up to 6.79% was achieved. The moth-eye structured PMMA film was fabricated by using an anodic aluminum oxide (AAO) template which is simple, low-cost and scalable. The nano-pattern of the AAO template was precisely reproduced onto the PMMA film...
March 15, 2017: Materials
Xiaobo Chen, Yu Tang, Weiwei Liu
A photoanode material ZnO nanoflower (ZNFs) for efficient dye-sensitized solar cell (DSSC) was prepared. This unique structure can significantly increase the specific surface area and amount of light absorption, leading to a higher short-circuit current density. Furthermore, ZNFs resulted in closer spacing between the nanorods and more direct conduction paths for electrons, leading to higher open-circuit voltage. The overall promising power conversion efficiency of 5.96% was obtained with photoanodes of 8.5 μm thickness...
August 3, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Shoushuang Huang, Dui Ma, Zhangjun Hu, Qingquan He, Jiantao Zai, Dayong Chen, Huai Sun, Zhiwen Chen, Qiquan Qiao, Minghong Wu, Xuefeng Qian
Platinum (Pt) -based alloys are considerably promising electrocatalysts for the reduction of I‒/I3‒ and Co2+/Co3+ redox couples in dye-sensitized solar cells (DSSCs). However, it is still challenging to minimize the dosage of Pt to achieve comparable or even higher catalytic efficiency. Here, by taking full advantages of the Mott-Schottky (M-S) effect at metal-semiconductor interface, we successfully strategize a low-Pt-based M-S catalyst with enhanced electrocatalytic performance and stability for the large-scale application of DSSCs...
August 2, 2017: ACS Applied Materials & Interfaces
Thomas W Rees, JinFeng Liao, Alessandro Sinopoli, Louise Male, Giuseppe Calogero, Basile F E Curchod, Etienne Baranoff
A series of six homoleptic bis-cyclometalated ruthenium complexes, Ru(N^N^C)2, is reported where N^N^C is a 6-(2,4-difluoro-3-R(3)-phenyl)-4-R(2)-4'-R(1)-2,2'-bipyridine with R(3) = -H or -CF3 and R(2) and R(1) = -COOEt or -CF3. An effective synthesis of the ligands and the complexes is described. The UV-visible absorption studies demonstrate that these complexes are panchromatic dyes absorbing up to 900 nm. Importantly, the onset of absorption depends only on the substitution on the metalated phenyl, whereas the intensity of absorption throughout the spectra is a function of substituents on both the phenyl and the bipyridine moieties...
August 1, 2017: Inorganic Chemistry
Chin-Ti Chen, Shih-Chieh Yeh, Li-Jing Wang, Hong-Ming Yang, Yu-Huei Dai, Ru-Jong Jeng, Chiao-Wen Lin
Including MPBTCA, which is a literature known compound, seven BODIPY dyes have been characterization by varied physical methods, such as UV-visible absorption spectroscopy, low energy photo-electron spectroscopy (AC-2), HOMO-LUMO DFT/TDDFT calculation. All seven BODIPY dyes have absorption max around 535-545 nm, which is significantly longer than 499 nm of 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene (PM 546). Having structural variation on donor group, acceptor group, donor -spacer, acceptor -spacer, and the substituent on boron, some BODIPY dyes exhibit small extinction coefficient or spectral integral in solution (MPCtBTCA, MPBT-pyO, MPBTT-pyO, MTBTCA), broadening absorption spectral profile (MTBTCA), weak intramolecular charge transfer characteristics (MPBT-pyO, MPBTT-pyO, MTBTCA), too low LUMO energy level (PPBTCA), insufficient dye-uptake by TiO2 FTO (MPBT-pyO, MPBTT-pyO, MTBTCA)...
August 1, 2017: Chemistry: a European Journal
Qianji Han, Hongrui Wang, Yali Liu, Yajing Yan, Mingxing Wu
A monodisperse carbon sphere with high uniformity, high catalytic activity and conductivity are successfully synthesized. Versatile counter electrodes using this carbon sphere catalyst on different substrates of fluorine-doped tin oxide (FTO) glass, indium-doped tin oxide polyethylenena phthalate (ITO-PEN), and Ti foil are fabricated for dye-sensitized solar cell (DSC). The impacts of substrates on the catalytic activities of the carbon sphere counter electrodes have been also evaluated by electrochemical analysis technologies, such as cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization curves...
July 24, 2017: Journal of Colloid and Interface Science
Asiful Alam, Simone Dehm, Frank Hennrich, Yuriy Zakharko, Arko Graf, Moritz Pfohl, Ihteaz M Hossain, Manfred M Kappes, Jana Zaumseil, Ralph Krupke, Benjamin S Flavel
Monochiral (7,5) single walled carbon nanotubes (SWCNTs) are integrated into a field effect transistor device in which the built-in electric field at the nanotube/metal contact allows for exciton separation under illumination. Variable wavelength spectroscopy and 2D surface mapping of devices consisting of 10-20 nanotubes are performed in the visible region and a strong correlation between the nanotube's second optical transition (S22) and the photocurrent is found. After integration, the SWCNTs are non-covalently modified with three different fluorescent dye molecules with off-resonant absorption maxima at 532 nm, 565 nm, and 610 nm...
July 27, 2017: Nanoscale
Mateusz Gierszewski, Iwona Grądzka, Adam Glinka, Marcin Ziółek
The substitution of iodide electrolytes with cobalt ones has led to the current champion laboratory efficiencies for dye-sensitized solar cells (DSSCs). However, unlike with organic dyes, this strategy does not work with classical ruthenium dyes. Therefore, we compare DSSCs sensitized with a popular Ru dye (N719) using both types of electrolytes by exploring the electron dynamics occurring from sub-ps to seconds. An important limitation in the photocurrent of cobalt-based cells is revealed to be due to electron recombination between titania and oxidized Ru dyes, which is much higher than that in iodide-based cells and occurs on the time scale of tens and hundreds of ps...
August 9, 2017: Physical Chemistry Chemical Physics: PCCP
Saba Ashraf, Erol Yildirim, Javeed Akhtar, Humaira M Siddiqi, Ahmed El-Shafei
In this study, we report the synthesis of a novel heteroleptic Ru(ii)-sensitizer, (Ru(2,2'-bipyridine-4,4'-dicarboxylic acid)-4,4'-bis(4-piperidin-1-yl)phenyl ethenyl)-(2,2'-bipyridine) (NCS)2, denoted as SD-1; moreover, its photophysical, electrochemical, and photovoltaic performances were compared with those of N719 and K77-7 (N,N'-diaryl Ru-sensitizer, namely Ru(2,2'-bipyridine-4,4'-dicarboxylic-acid)-4,4'-bis(2-(4-N,N'-diphenylaminophenyl)ethenyl)-2,2'-bipyridine (NCS)2). The photovoltaic performance of SD-1 outperformed those of N-719 and K77-7, particularly in the red region, and the overall efficiency of SD-1 was 8...
August 9, 2017: Physical Chemistry Chemical Physics: PCCP
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"