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[Display omitted] • A novel inorganic perovskite nanomaterial, AlMo 0.5 O 3 , was synthesized. • Several AlMo 0.5 O 3 amounts were added to the TiO 2 photoanode of DSSCs. • The highest efficiency of 5.30% was measured for the cell containing 0.5% AlMo 0.5 O 3. • The champion device exhibited J SC = 10.96 mA.cm−2, V OC = 0.76 V and FF = 0.64. • The lowest recombination of charge carriers was happened in the champion DSSC. To enhance the photovoltaic efficiency of dye sensitized solar cells (DSSCs), tri-layered photoanodes composed of compact, mesoporous and light scattering TiO 2 layers were fabricated. Moreover, inorganic AlMo 0.5 O 3 perovskite nanomaterial was synthesized using sol gel method and different AlMo 0.5 O 3 /TiO 2 nanocomposites were achieved by adding various amounts (0–3.0%) of the AlMo 0.5 O 3 nanoparticles to the mesoporous TiO 2 layer in the photoanode. All of the nanocomposite photoanodes and the AlMo 0.5 O 3 nanostructure were characterized by XRD, SEM, EDS, DRS, photoluminescence (PL) and FT-IR analysis techniques. Also, the effect of AlMo 0.5 O 3 nanoparticles on the power conversion efficiency (PCE) of the DSSC devices was examined. The measured optical band gaps of all nanocomposite photoanodes were calculated in the range of 2.68–3.10 eV. The photovoltaic parameters extracted from the J-V plots of the DSSCs illustrated that the champion cell fabricated using mesoporous TiO 2 + 0.5%AlMo 0.5 O 3 nanocomposite photoanode had PCE = 5.30% with J SC = 10.96 mA.cm−2, V OC = 0.76 V and FF = 0.64. This result revealed that the TiO 2 + 0.5%AlMo 0.5 O 3 composite increased the device efficiency by 2.79 times as compared to the DSSC fabricated using bare TiO 2 (champion PCE = 1.90% with J SC = 7.90 mA.cm−2, V OC = 0.67 V and FF = 0.36). Comparing the J SC and V OC values of the champion device with those of the DSSC with bare TiO 2 photoanode confirmed that incorporation of the AlMo 0.5 O 3 in TiO 2 layer highly improved the charge transfer in the device and simultaneously declined the recombination of charge carriers. Hence, the perovskite AlMo 0.5 O 3 could be suggested as an efficient nanomaterial for application in DSSCs. [ABSTRACT FROM AUTHOR]

• Novel titania comprising nanoparticles grown on nanorods explored as photoanodes. • 1D TiO 2 nanostructures with large specific surface area and suitable porosity. • Significant current density (J sc) of 15.84 mA/cm2 and efficiency (η) of 7.64%. • Enhanced current density (37%) and efficiency (41%) compared to P25 precursor. In this work, the impact of alkali concentration on the formation of novel one dimensional TiO 2 nanostructures has been studied. The variation of alkali concentration resulted in the change of morphology and structure of P25 nanoparticle precursors under hydrothermal conditions, as confirmed by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) nitrogen adsorption–desorption, X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. The effects of the annealing temperatures on the surface oxygen vacancies were also studied under various temperatures. In higher NaOH concentrations under annealing, these nanostructures have a peculiar appearance consisting in nanorods with nanoparticles grown on their surface and hence designated herein as "integrated TiO 2 nanorods". The prepared nanostructures were employed as main precursors of photoanode and their performance was fully investigated in dye-sensitized solar cells (DSSCs). TiO 2 nanostructures prepared from 12 M alkaline solution at 300 °C had the largest specific surface area (363.15 m2/g) and the best efficiency improvement was about 41% for these TiO 2 nanostructures compared to the P25 nanoparticles. [ABSTRACT FROM AUTHOR]

We have predicted four squaraine (SQ) structures with different heterocyclic anchoring groups (HAGs), including hydantoin moiety (HY), rhodanine (RD), 2-(1,1-dicyanomethylene) (DCRD) and barbituric acid (BA), to simultaneously enhance the lower open-circuit photovoltage ( V oc ) and adsorption stability of the gold-standard SQ dye with widely used carboxylic acid anchoring group (CA) without sacrificing its extremely large short-circuit current ( J sc ). For the first time, these HAGs are put together to discuss their impacts on the relative adsorption stability and the intrinsic reasons affecting the V oc , including adsorption modes, conduction band energy shift (Δ E CB ), electron injection, charge recombination, and the dye aggregation effects. Especially, charge decomposition analysis has been performed to explain the origin of different extent of Δ E CB , and the reduced density gradient analysis offers a pictorial representation of the weak interactions between the two monomers. The results show that the adsorption stability order is BA ≈ HY > RD ≈ CA > DCRD. And the V oc order is BA > HY > RD > CA > DCRD. In addition, we find these SQ dyes show comparable maximum photocurrent density (about 22 mA/cm 2 ). Thus, SQ dyes with BA, HY, and RD are promising candidates for the experimental synthesis of high-performance dye sensitized solar cells. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of well-known 4,4′-(4-(5-(2,2-dicyanovinyl)thiophen-2-yl)phenylazanediyl)dibenzoic acid ( O2) and its hypothetical dyes O3- O7 were investigated by computational techniques. The absorption properties were probed. By replacing the 2-methylidenepropanedinitrile acceptor with 1,3-diethyl-5-methylene-2-thioxo-dihydropyrimidine-4,6(1 H,5 H)-dione, the molecular orbital energy levels were well tuned. The modified dyes meet the basic requirements of both -Δ Ginj and -Δ Greg being over 0.2 eV for an efficient hole injection and dye regeneration, respectively. All the designed p-type dyes O3- O7 have smaller energy gap and significant red shift in absorption spectra than that of the reference O2. Finally, our results suggested that O3- O7 have larger light-harvesting efficiencies (LHE) in the visible spectral regions of 400 nm to 700 nm than O2. Among all the dyes, O5 is expected to have an excellent performance as a p-type sensitized dye in solar cells due to its great LHE and sufficient hole injection efficiency. [ABSTRACT FROM AUTHOR]

A Photoanode in dye sensitized solar cell is responsible for photoabsorption and conduction of the generated electrons for which TiO 2 is a highly employed material due to its non-toxic nature and low cost. This study reports a convenient and facile method to prepare un-doped and magnesium (Mg) doped TiO 2 thin films using Aerosol assisted Chemical Vapor deposition on Indium doped Tin oxide substrates. The as prepared films were subjected to morphological and structural characterizations as well as the optical absorption, band gap and surface area measurements of films. The studies indicated that Mg substituted Ti in the TiO 2 lattice and formed new energy levels which decreased the band gap of the doped films. Moreover, increasing the concentration of Mg shifted the optical absorption of the films from ultra-violet region to the visible region. The IV measurements of the DSSCs fabricated using 2 mol% Mg doped TiO 2 film, N719 dye, I − /I 3 − redox electrolyte and platinum sputtered on ITO counter electrode, revealed approximately twofold increase in overall efficiency of DSSCs as compared to undoped TiO 2 based DSSC. The increase in V oc and J sc , as well as the efficiency of 6.1%, is an indication that 2 mol% Mg doped TiO 2 film is a potential candidate as a photoanode material in DSSC. [ABSTRACT FROM AUTHOR]

In this work, we report on the modelling of light soaking effect on Ruthenium-based Dye Sensitized Solar cells (DSSCs). Such a phenomenon can be detected when exposing the cells at increasing hours of illumination and produces a reversible performance increase. Starting from the results obtained through the electro-optical characterization of the cells, we applied a one-diode circuital-model. Our results show a good agreement between the experimental and the simulated data, with a mean square error in the order of 10 −12 and a maximum error in current lower than 0.6%. Finally such results allowed us to infer some precise trends followed by the cells main electrical parameters and of their equivalent one-diode electrical model due to light soaking effect. [ABSTRACT FROM AUTHOR]

The strong adsorption stability and significantly improved incident photon-to-current conversion efficiency (IPCE) of the new anchoring group hydantoin moiety ( HY ) introduced into D-A-π-A dyes for dye sensitized solar cells (DSSCs), compared with the commonly used anchoring group cyanoacrylic acid ( CA ), were investigated through DFT/TD-DFT calculations on the dye@(TiO 2 ) 48 interfacial electron dynamics for the first time. It is found that the dissociative bidentate bridging mode with a hydrogen bond is the most stable adsorption configuration on the TiO 2 anatase (101) surface for HY -based dyes and could produce a dramatic increase in adsorption energy compared with that of CA -based dye. Energy decomposition analysis (EDA) was performed to elucidate the different adsorption energies for the different anchoring groups with different adsorption configurations. A simplified Tamm-Dancoff density functional theory approach (sTDA-DFT), proposed by Grimme, was used to calculate the excitation energy and oscillator strength of the sensitizers after adsorption. The calculated results indicate that the adsorption mode has significant effects on the absorption spectrum. In contrast to CA -based dye, HY -based dye exhibits comparable light harvesting ability after adsorption due to the combined effects of different adsorption configurations, although the isolated dye exhibits a blue-shifted absorption spectrum. It shows a similar electron injection and dye regeneration driving force, but the significantly larger coupling between the sensitizer and the semiconductor for HY -based dye is the main reason for its improved IPCE. Moreover, to further improve the light-harvesting ability of the dyes, two other heterocyclic groups, rhodanine ( RD ) and 2-(3-oxo-2,3-dihydroinden-1-ylidene)-malononitrile ( MT ), were introduced into the dyes as anchoring groups. The results show that dyes with the RD anchoring group exhibited significantly enhanced light harvesting ability with the red-shifted absorption spectrum, higher electron injection efficiency with larger electronic coupling and strong adsorption ability; thus, it is worthy of experimental synthesis for use in high-performance dye sensitized solar cells. [ABSTRACT FROM AUTHOR]

With flexibility practices becoming a vital concern for dye sensitised solar cells (DSSCs) today, researchers are widely developing choices of excel conductivity and durable anode substrate, which is metal. As metals are exposed to light impenetrability caused by its opacity, the illumination sides were transitioned from the front-side to backside of the DSSCs. The less light absorption reduces the power conversion efficiency (PCE). The surface treatment was posited onto the titanium (Ti) substrate in promoting a gap for titanium dioxide (TiO 2) during deposition, as well as discarding the oxide layer of the Ti surface. To improve the PCE for backside illumination DSSCs of Ti substrate, this paper proposes the embedment of silver nanoparticles (AgNPs) into TiO 2 at various concentrations between 1.0 wt% and 3.0 wt%. The AgNPs were produced by solvothermal method in sizes of 23 nm, 25 nm, 29 nm, and 36 nm. The chosen size of 29 nm has been laid on the ultraviolet-visible (UV-Vis) and transmission electron microscopy (TEM) with the highest absorbance and low status of agglomeration. The back-illuminated AgNPs-TiO 2 film acquired optimal PCE = 4.691%, J sc = 10.0 mA/cm2, FF = 0.67, and V oc = 0.70 mV in response to the 2.0 wt% concentration of AgNPs-TiO 2 deposited onto a flexible Ti substrate. [ABSTRACT FROM AUTHOR]

In this work, we report on the electro-optical characterization of Dye Sensitized Solar Cells (DSSCs) which use ruthenium complexes as sensitizers. In particular, several kinds of measurements have been performed to study the electrical performances and the efficiency levels of the cells at different operating conditions. In detail, the measurements have been conducted at varying temperatures and hours of light soaking. Our results show that the short circuit current density J SC , the open circuit voltage V OC and the conversion efficiency η increase with the hours of light soaking, while they decrease with temperature. A thorough investigation on the light soaking process at the device level has been carried out, giving a wealth of experimental data which can be very useful to better single out and quantify the underlying physical phenomena and the effects on the cell parameters, which are still controversial among the scientific community. Finally, the ageing study demonstrates that the cell performance rapidly deteriorates in the first few months of exposure to light. All the obtained results are of great importance for a better understanding of the light soaking phenomenon and for improving the fabrication process of the DSSCs investigated during this study. [ABSTRACT FROM AUTHOR]

Pt/Pd hollow nanofibers were obtained by sputtering a Pt/Pd alloy (80/20 wt%) onto polymer nanofibers (used as sacrificial template) and were used as counter-electrodes (CEs) in dye-sensitized solar cells (DSSCs). We demonstrate that optimization of nanofiber density and Pt/Pd sputtering thickness can increase the short circuit current density and consequently lead to a ∼15% enhancement in power conversion efficiency (PCE), when compared to the commonly used flat Pt/Pd CEs with the same thickness. The processes that contribute to such PCE improvement are: (i) increased surface area provided by the high aspect ratio hollow nanofibers and (ii) improved electro-catalytic performance, as validated by electrochemical impedance spectroscopy (EIS) measurements. The latter showed a two-fold decrease in the charge-transfer resistance of the nanostructured-CE, compared to the flat CE. The contribution of the Pt/Pd hollow nanofiber to light scattering was negligible as shown by reflectance measurements. These results suggest a simple and straightforward strategy to increase PCE in DSSCs, to minimize the use of precious metals used in this kind of devices and, more generally, to tailor the CE structure in photoelectrochemical systems to boost their functional properties, thanks to the advantages afforded by this complex morphology. [ABSTRACT FROM AUTHOR]

Dye-Sensitized Solar Cells (DSSCs) provide high power conversion efficiency, flexibility, transparency and simple fabrication at low cost. This research focuses on synthesizing high ordered Silver (Ag) nanowires via anodic aluminum oxide (AAO) templates by electrodeposition method. Ag nanowires/Polypyrrole (PPy) nanocomposites for the counter electrode (CE) of DSSC are fabricated to be a cost-effective and efficient alternative for platinum (Pt) based counter electrode (CE). Structural analysis of Ag NWs and PPy exhibits its crystal structure to be FCC and triclinic, respectively. By incorporating Ag NWs/PPy nanocomposites, catalytic properties and electrical conductivity of the CE have been aggravated remarkably. The spin coating technique is used to synthesize Ag NWs and PPy nanocomposites for deposition on Fluorine-doped Tin Oxide (FTO) glass. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that the nanocomposites of Ag NWs/PPy show good electrocatalytic activity in Oxidation/Reduction of iodide electrolyte solution as compare to platinum. Minimum peak to peak potential difference (∆E PP) obtained from CV curves determined the high electrocatalytic properties of the Ag NWs/PPy nanocomposites for the counter electrode. The conclusions may provide a supportive direction for the fabrication of high power conversion efficiencies (PCE) DSSCs. [ABSTRACT FROM AUTHOR]

In this work we investigate electrolyte degradation mechanisms in a Dye Sensitized Solar Cell (DSSC), when stressed under forced reverse bias (RB) conditions. During the stress test, we observe a gradual and visually evident cluster shaped browning of platinised counter-electrode in contact with electrolyte solution; Raman spectroscopy confirms that the observed phenomena is due to formation of polyiodide ions and reveals an arose marked fluorescence background, stemming from new chemical species induced by RB stress test. Raman and fluorescence measurements on RB stressed model electrolyte solutions reveal that photoluminescence emission is mainly related to degradation mechanisms involving the I − /I 3 - redox couple. In fact, due to the RB stress, the redox couple is unbalanced and the formation of various associated structures between 1-methyl-3-propyl imidazolium iodide (PMII) ions is favored. This can be detected by observing the Red Edge Effect (REE) in fluorescence emission spectra of stressed solutions. Thus, polyiodides formation in RB stressed DSSCs could be added to the several depletion channels of triiodide anions and should be taken into account in designing new stable and efficient electrolytes. [ABSTRACT FROM AUTHOR]

The inorganic perovskite and spinel materials have exhibited lots of desirable characteristics which make them promising materials for usage in dye sensitized solar cells (DSSCs). Photoanode in DSSCs is made up of a metal oxide semiconductor (usually TiO 2). To attain high power conversion efficiency (PCE) for a DSSC, photoanode should reveal high amounts of dye adsorption, light scattering and photoelectron injection. The TiO 2 photoanode displays several drawbacks such as long dye absorption time, low electron mobility, formation of complex with the dye molecules, and relatively high recombination of charges at its interface with the electrolyte. Accordingly, other metal oxides such as spinel and inorganic perovskite compounds could be utilized to replace and/or modify the TiO 2 photoanode of DSSCs. The mineral spinel is zinc aluminate (ZnAl 2 O 4) and the spinel materials have the general AB 2 X 4 formula, where A, B show metal cations while X represents anions such as O2− and halide (F−, Cl−, Br−, I−) anions. The mineral perovskite is calcium titanate (CaTiO 3) and the formula of the perovskite materials is commonly illustrated as the ABX 3 , where X represents the anions and A, B display metal cations. Herein, a comprehensive review was accomplished on using the perovskite and spinel materials in photoanodes of DSSCs. The studied inorganic perovskite materials were BaSnO 3 , BaTiO 3 , SrTiO 3 , CdSnO 3 , CoTiO 3 , Ba 3 Ti 4 Nb 4 O 21 and A 2 LuTaO 6 (A = Ba, Sr, Ca) and the spinel materials included Zn 2 SnO 4 , CuBi 2 O 4 , NiCr 2 O 4 , SrAl 2 O 4 and ZnFe 2 O 4 structures. It was displayed that the PCEs of the fabricated DSSCs were enhanced upon employing certain amounts of the perovskite or spinel materials. [Display omitted] • Applications of AB 2 X 4 spinels were reviewed in photoanodes of dye sensitized solar cells (DSSCs). • Applications of inorganic ABX 3 perovskite materials were reviewed in photoanodes of DSSCs. • Replacement and/or modification of the TiO 2 photoanodes of DSSCs were reviewed. • Increasing the power conversion efficiencies (PCEs) of modified DSSCs was reviewed. • Achievement of superior photovoltaic characteristics was reviewed for modified DSSCs. [ABSTRACT FROM AUTHOR]

Two new Ru(II) complexes bearing with substituted dipyrrinato ligands ( GS3 and GS10 ) have been successfully synthesized and characterized. These sensitizers exhibit panchromatic light harvesting properties, rendering them promising for DSSC applications. GS3 has shown high overall power conversion efficiency (η = 2.79%) compared to GS10 which is the highest so far in the case of Ru (II) dipyrrinato dyes. Density functional theory (DFT) and time-dependent DFT calculations were measured for GS3 and GS10 to understand their structural, electronic and photophysical properties. [ABSTRACT FROM AUTHOR]

We designed and synthesized a new ruthenium complex using terpyridine as an anchoring ligand and BOC ( tert -butyloxycarbonyl) protected bidentate benzimidazole derivative as an ancillary ligand, coded as GS7 . The complex was characterized using 1 H NMR, FTIR, elemental analysis, UV–vis spectrophotometer, and cyclic voltammetry. We also tested photovoltaic performance of this complex for dye-sensitized solar cell (DSSCs). GS7 when used as a sensitizer for DSSCs with iodine triiodide electrolyte, showed a J sc of 15.25 mA cm − 2 , a V oc of 0.576 V, a FF of 0.691 and overall power conversion efficiency of (η) 6.07%. [ABSTRACT FROM AUTHOR]

Boron doped diamond (BDD) shows high chemical stability in contact with a liquid phase even under extreme pH conditions, high electrochemical activity, and allows very stable covalent functionalization on O- or N-terminated surfaces. It is therefore an excellent electrode material for many applications such as analytics, biosensors, and purification. Furthermore, the electrodes can be covalently functionalized with photo-sensitive dyes to generate photo currents. However, the energetic conditions and charge transfer mechanisms are not fully known and therefore have been investigated in this work. The focus was set on the energy band diagrams of nanocrystalline diamond (NCD) layers, especially on the flat-band potential VF and the band-bending ϕB in the space charge layer, for both O- and N-terminated surfaces, and the charge transfer mechanisms at the semiconductor/electrolyte phase-boundary, with or without electro-active organic dyes, such as manganese phthalocyanine. For this study NCD samples were grown by hot filament chemical vapor deposition (HFCVD) with a boron doping density NA ranging between 5.8 and 9.6 × 1020 cm−3. The pristine surface was then processed by oxygen or ammonia plasma to modify the termination to O and NH2, respectively. After that a series of Mott-Schottky plots was measured for both terminations at several frequencies spanning from 3 Hz to 10 kHz and in two different electrolytes, namely 0.1 M H2SO4 and 0.1 M KCl. The results showed nearly the same flat-band potential for both surface terminations, but a remarkable difference in the band-bending. The latter is most probably responsible for the better photoelectrical conversion observed in N-terminated NCD samples. The open-circuit potential (OCP) and chronoamperometric measurements performed after covalent functionalization of the samples with the color dyes revealed that only the N-terminated material delivered a measurable photocurrent. Although the global efficiency of the photoelectric conversion was low, these initial results show that by optimized selection of materials and modification technologies providing a proper match of the energy levels at all charge transfer steps, a higher energy output could be achieved. [ABSTRACT FROM AUTHOR]

Due to their low cost, facile fabrication, and high-power conversion efficiency (PCE), dye-sensitized solar cells (DSSCs) have attracted much attention. Ruthenium (Ru) complex dyes and organic solvent-based electrolytes are typically used in high-efficiency DSSCs. However, Ru dyes are expensive and require a complex synthesis process. Organic solvents are toxic, environmentally hazardous, and explosive, and can cause leakage problems due to their low surface tension. This review summarizes and discusses previous works to replace them with natural dyes and water-based electrolytes to fabricate low-cost, safe, biocompatible, and environmentally friendly DSSCs. Although the performance of "eco-friendly DSSCs" remains less than 1%, continuous efforts to improve the PCE can accelerate the development of more practical devices, such as designing novel redox couples and photosensitizers, interfacial engineering of photoanodes and electrolytes, and biomimetic approaches inspired by natural systems. [ABSTRACT FROM AUTHOR]

Highlights: [•] A colloidal TiO2 ink assists the low temperature manufacturing of photoanodes. [•] The ink key component is a TiO2 colloid stabilized with 3,6,9-trioxadecanoic acid. [•] 3,6,9-Trioxadecanoic acid was linked to titania colloid through labile hydrogen bonds. [•] The optimized ink has a simple composition, high stability and homogeneity. [•] DSSCs had a 5.6% efficiency after a soft thermal treatment (140°C). [ABSTRACT FROM AUTHOR]

Abstract: We report the improvement of the operational stability of dye-sensitized solar cells (DSSCs) by incorporating multi-wall carbon nanotubes (MWCNTs) in conventional nanostructured semiconducting TiO2 photoanodes. DSSCs were prepared by adding various concentrations of MWCNTs (up to 1.0% wt.) to TiO2 anatase nanoparticles. Optimization of MWCNT concentration leads to photoconversion efficiency as high as 4.1% as opposed to 3.7% for pure TiO2 photoanodes. The performance of the solar cells was measured for 10 consecutive days of continuous ambient light exposure. MWCNT addition results in the decrease of efficiency from 4.1% to 3.7%, while a decrease from 3.7% to 2.4% was recorded in pure TiO2 photoanodes. These results are encouraging toward the commercial exploitation of DSSCs. [Copyright &y& Elsevier]

Four polyene-diphenylaniline dyes (D5, D7, D9 and D11) are simulated here, for the first time, as sensitizers for nano-ZnTiO 3 -based dye-sensitized solar cells (DSSCs). First-principles calculations method has been used to describe dye-semiconductor surface interactions. Bonding between the ZnTiO 3 nanoparticle, considered as (ZnTiO 3) 8 cluster, is studied using density-functional theory (DFT) and time-dependent (TD-DFT). Dye parameters have been used in analyzing electron-transfer processes from dye excited molecules into semiconductor. Electronic structures and simulated UV–Vis spectra of four dyes (isolated and ZnTiO 3 -bound forms) are described together with energy level diagrams and electrochemical parameters. Results are compared with earlier experimental results and used to discuss parameters that affect DSSC performance. The excited D11 (with −2.0173 eV level) has highest electron injection rate toward the ZnTiO 3 conduction band. D9 (with −0.5369 eV level) is regenerated, by I − / I 3 − redox couple, more efficiently than D5, D7 and D11 dyes, with minimal charge-recombination rates. Moreover, D9 displays highest peak absorption, in both free form (at 544 nm) and adsorbed form (at 563 nm). D5 and D9 exhibit high Light Harvesting Efficiency values 0.7752 and 0.8416, respectively, between dye LUMO and ZnTiO 3 conduction-band, compared to D7 (0.4921) and D11 (0.5441). D9 exhibits highest open-circuit potential (V OC , 0.88 eV) while D5, D7 and D11 have 0.79, 0.47 and 0.29 eV, respectively. The D9@ZnTiO 3 interface shows highest stability with largest adsorption energy (−47.16 eV, −4550.62 kJ/mol) among different systems. Results indicate that D9@ZnTiO 3 -based DSSCs should exhibit highest power conversion efficiency (PCE) among the series. D-p-A properties of polyene-diphenylaniline dyes affect their HOMO and LUMO levels and consequently charge injection at dye/ZnTiO3 interface and regeneration at dye/redox couple interface in DSSCs. [Display omitted] • Four polyene-diphenyaniline dyes (D5, D7, D9 and D11) are simulated as sensitizers for n-ZnTiO 3 DSSCs, for the first time • Compared to earlier dyes, the present ones chemisorb onto ZnTiO 3 nano-particles more effectively • Dye HOMO and LUMO level suitability for ZnTiO 3 is discusses to predict electron injection and dye regeneration [ABSTRACT FROM AUTHOR]

Abstract: We report the preparation of nanoporous TiO2 electrode modified with an insulating material—BaCO3 and used as electrode for quasi solid state dye sensitized solar cells (DSSCs), with a benzothiadiazole-based dye (BTDR2) as sensitizer and PEDOT:PSS coated FTO as counter electrode. We found that the BaCO3 modification significantly increases the dye adsorption, resulting from the fact that the surface of BaCO3 is more basic than TiO2. The performance of the DSSCs with and without BaCO3 modified TiO2 electrodes were analyzed by cyclic voltammograms, optical absorption spectra, current–voltage characteristics in dark and under illumination and electrochemical impedance spectra. The photovoltaic performance has been significantly improved for the BaCO3 modified electrode as compared to bare TiO2 electrode having the same other components in the DSSCs. The value of the overall power conversion efficiency (η) improves from 2.42% to 4.38% under illumination intensity, when BaCO3 modified electrode is used instead of bare TiO2 electrode. The improvement in η has been attributed to the increased dye adsorption, reduction in recombination rate and enhancement in the electron lifetime when the modified TiO2 electrode is used. [Copyright &y& Elsevier]

Eight novel T shaped phenothiazine/carbazole based organic dyes with naphthalimide as π-spacer were designed, and the geometries, electronic structures, and optical features of these isolated dyes and dye-(TiO 2) 9 systems were investigated with density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations. Some quantify factors influencing the energy conversion efficiency (PCE) such as the light harvesting efficiency (LHE), electron injection driving force (Δ G inject) and dye regeneration driving force (Δ G reg) were also calculated for dye-sensitized solar cells (DSSCs) applications. It is found that these dyes show a good performance of electron injection and dye regeneration owing to the proper value of Δ G inject and Δ G reg. The optimized geometries of the non-planar molecular configuration of donor and the planar structure of the naphthalimide conjugated bridge are beneficial to efficient intramolecular charge transfer and the suppression of molecular aggregation. The properties about the electronic structure and absorption spectra indicate that replacement of benzene with thiophene unit near to cyanoacetic acid acceptor can generate more efficient conjugation effect and achieve red shift of absorption spectra, resulting a higher J sc and V oc in DSSCs device. The theoretical results reveal that DTPH2, DTPH4, DTCA2 and DTCA4 would be used as potential sensitizers for DSSCs applications. Unlabelled Image • Eight novel phenothiazine/carbazole based T shaped dyes with naphthalimide as π-spacer were designed. • The non-planar donor part and the planar conjugated bridges are beneficial for DSSCs applications. • The studied dyes show a good performance of intramolecular charge transfer, electron injection and dye regeneration. • Replacement of benzene with thiophene unit near to cyanoacetic acid can generate red shift of absorption spectra. [ABSTRACT FROM AUTHOR]

The sensitization activity of four zinc metalloporphyrin dyes: meso -tetrakis(4-pyridyl)porphyrinato Zn(II) (a), meso -triphenyl-(4-carboxyphenyl)porphyrinato Zn(II) (b), meso -tetrakis(4-carboxyphenyl)porphyrinato Zn(II) (c) and meso -tripyridyl(4-carboxyphenyl)porphyrinato Zn(II) (d) is reported here, in terms of current-potential curve, open-circuit potential, fill factor, and overall solar energy conversion efficiency which have been evaluated under 100 mW/cm2 light intensity and their performances compared to the benchmark N719 (di-tetrabutylammonium cis- bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato) ruthenium(II)). This work focus the structural aspects of dyes with anchoring groups using TiO 2 -based Dye Sensitized Solar Cells (DSSCs), which includes pyridyl and carboxyphenyl acid groups and argue how the combination of both anchoring groups, in the same structure, may allow relevant optimization of DSSCs performance in the near future. Also, a noticeable improvement in the photovoltaic performance of all dyes, reaching a maximum increase from 25% to 69% in the overall DSSC efficiency under short periods of white light illumination is discussed. Image 1 • Here we present and discuss some aspects of four meso -substituted porphyrins, particularly the effect on the photovoltaic performance in DSSC considering the number of p -carboxyphenyl anchoring groups. • The anchoring character of pyridyl meso-substituent, is observed only in the presence of at least one p-carboxyphenyl group in the porphyrin structure. • The significant and simultaneous improvement in all photovoltaic parameters, when exposed to short periods of white light illumination, suggests a complex phenomenon that deserves attention in the near future. [ABSTRACT FROM AUTHOR]

• Designed and synthesized six new metal-free 2-cyanoacetanilide based organic dyes (SA1-6) for DSSC application. • All the dyes possess the thermodynamic requirements to be used as DSSCs. • The dyes SA4-6 bearing pyridine moiety showed better efficiency than that of dyes SA1-3 with nitro group. • SA1 co-sensitized with HD-2 displayed the best efficiency (η) of (8.02%) with increasing in both V OC (0.68 V) and J SC (20.33 mA/cm2). The design, synthesis and photovoltaic performance of metal-free 2-cyanoacetanilide based organic dyes, SA1-6 have been reported as sensitizers / co-sensitizers in dye sensitized solar cells (DSSCs). All dyes possess the thermodynamic requirements to be applied in DSSCs. The DFT and TD-DFT calculations were completed using Guassian09 package software. The obtained results showed appropriate charge separation between the ground state oxidation potential (GSOP) and excited state oxidation potential (ESOP) levels of the dyes. In addition, there was a good a greement between the theoretical and experimental data. Over co-sensitization, SA1-6 exhibited better efficiency than the main sensitizer HD-2. Among the dyes we synthesized, SA1 displayed improved PCE of 8.02 % with increasing in both V OC value of 0.682 V and J SC value of 20.33 mA/cm2, whereas the DSSC fabricated with dye HD-2 alone showed PCE of 7.49 % with J SC of 19.01 mA/cm2 and V OC of 0.63 V. Finally, Electrochemical impedance spectroscopy measurements, beside electron lifetimes of SA1-6 and HD-2 , were obtained and are in good agreements with the experimental photovoltaic parameters. [ABSTRACT FROM AUTHOR]

The Power Conversion Efficiency (PCE) of back illuminated dye sensitized solar cells (DSSCs) using Titanium Dioxide (TiO 2) printed on Titanium foil photo-anode was investigated. It is essential to study the optimum volume of the Platinum (Pt) catalyst solution spin-coated on counter electrode and the TiO 2 absorbance layer optimized thickness for optimum light harvesting in a back illuminated structure. In this study, we have concentrated on the optimized 11 μm thick of TiO 2 film assembled on the photoanode using Doctor Blade printing method. The 11 μm thick films were tested in a constraint of Platinum contents obtainable from 30 μl, 50 μl and 70 μl volumes of Pt solutions. The same cells were also subjected to front illumination to compare the results. The back illuminated optimization was achieved with the 11 μm TiO 2 film thickness which was at PCE = 2.99%, Jsc = 7.83 mA/cm2, Voc = 0.7V, FF = 0.55 with the minimum volume of the Pt solution. From the selected ideal thickness of 11 μm TiO 2 film performances of the Fluorine Tin Oxide (FTO) glass as solid state photoanode during back illumination, a similar methodological structure was imposed on Titanium foil based anode cells where the achievement was indicated at PCE = 2.75%, Jsc = 4.62 mA/cm2, Voc = 0.71V, FF = 0.84 for a 70 μl volume of Pt solution. The results show that for a solid state photoanode substrate, 30 μl of Pt solution is sufficient to provide catalytic activities and at the same time allow light penetration to the active region, whereas the flexible photoanode requires a higher concentration of Pt solution for rapid catalytic capabilities. [ABSTRACT FROM AUTHOR]

Based on a prototype sensitizer W2, we designed triarylamine-based p-type sensitizers W2-1 to W2-7 that contain modified π-spacers (π'), a π-spacer and two anchors. For W2-1 to W2-4, instead of 2,1,3-benzothiadiazole in W2, thieno[3,4-b]-1,4-dioxin, thiophene, thieno[3,4-c][1,2,5]thiadizole, thiazolo[5,4-d]thiazole are π' and thiophene as π-spacer. For W2-5 to W2-8, π' and π are same, with 2,1,3-benzothiadiazole, thieno[3,4-b]-1,4-dioxin, thieno[3,4-c][1,2,5]thiadiazo, thiazolo[5,4-d]thiazole, respectively, as the π'-spacers. Structure optimization, electronic level and absorption characters were calculated with density functional theory (DFT) and time-dependent DFT (TDDFT) at the CAM-B3LYP/6-311G (d,p). The solvent effect was involved using a polarized continuum model in chloroform. The results showed that the highest occupied molecular orbital and the lowest unoccupied molecular orbital guarantee sufficient hole injection (lower than -0.2 eV), and dye regeneration (lower than -0.2 eV). W2-4 has higher light-harvesting efficiency (LHE) (0.994) and larger overlap with the visible light from 400 nm to 600 nm. Finally, the results suggest that the driving force of hole injection, dye regeneration and charge recombination (ΔGinj, ΔGreg and ΔGCR) of W2-4 are the best, with more negative ΔGinj (-4.33), ΔGreg (-1.74) and more positive ΔGCR (1.92). Replacing 2,1,3-benzothiadiazole with thiazolo[5,4-d]thiazole as π'-spacers is a effective way to improve the performance of the dyes. An introduction of thiazolo[5,4-d]thiazole group can improve the absorption ability and hinder charge recombination.Absorption spectra of p-type D-π-A sensitizers with modified π-spacers [ABSTRACT FROM AUTHOR]