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We have developed a series of Ru sensitizers (GS16, GS17 and GS19) with molecular architecture containing a tridentate ligand with one, two and three anchoring groups and three thiocyanates. Furthermore, we have studied the effect of the number of carboxylic groups on photovoltaic properties. The absorption spectra of the novel sensitizers extended up to the red region (900 nm). The electrochemical studies reveal that the oxidation potentials are aligned below the iodine-based redox potential, feasible for easy regeneration, and the lowest unoccupied molecular orbital of all sensitizers lies above the TiO2 conduction band, which is favourable for easy electron injection. The overall efficiency (η) of the GS16, GS17 and GS19 is 1.13, 2.71 and 1.59% with short-circuit current (J SC) of 3.74 mA cm−2, 7.08 mA cm−2, 6.27 mA cm−2, open-circuit voltage (V OC) of 0.42 V, 0.54 V and 0.39 V and fill factor of 0.70, 0.70 and 0.65, respectively. The highest efficiency of 2.71% was observed in GS17, bearing the two anchoring groups compared to one and three carboxylic acid-containing sensitizers (GS16 and GS19). Theoretical studies are also examined and matched with the experimental data. [ABSTRACT FROM AUTHOR]

Context: This study aims to investigate the electronic transport properties of tetracene molecule connected to gold (Au) electrodes with asymmetric anchoring groups. More specifically, we investigate the effect of asymmetric electrode coupling on the rectification ratio of tetracene-based molecular device. To introduce coupling asymmetry in these junctions, one end of the tetracene molecule is terminated with thiol (−SH) or isocyanide (−NC) while the other end with amine (−NH2) or nitro (−NO2) anchoring group. The results indicate that the electronic transport behavior is affected by the nature of molecule-electrode coupling, and the rectification ratio can be modulated by a proper choice of the anchoring groups. We reveal that the tetracene molecule when connected with isocyanide and amine combination exhibits remarkable rectifying performance (with a rectification ratio of 74) in contrast with other configurations. Furthermore, a prominent negative differential resistance (NDR) feature is observed when the molecule is connected with thiol as one of the anchors. Our present findings with excellent rectifying performance and negative differential resistance pave a new roadmap for designing multifunctional molecular devices. Methods: By applying non-equilibrium Green's function (NEGF) formalism combined with density functional theory (DFT) Atomistic Tool Kit software package, the electronic transport properties of tetracene molecule connected to gold electrodes with asymmetric anchoring groups have been investigated. The calculations were performed using the Perdew-Burke-Ernzerhof (PBE) parameterization of DFT within generalized gradient approximation (GGA) exchange-correlation functional. To improve calculation precision and save computational efforts, the molecule and anchor groups were double-ζ (DZ) polarized, while single-ζ (SZ) polarized basis set was used for gold electrodes. [ABSTRACT FROM AUTHOR]

Anchoring groups are crucial for enhancing the performance of dye-sensitized solar cells (DSSCs). For instance, cyanoacrylic acid serves as the primary anchoring group in DSSC due to its crucial elements required for effective electron transport. However, it suffers from degradation. To address this limitation, this study proposes alternative cyano-based anchoring groups for sensitizers. Density functional theory (DFT) and time-dependent DFT were used to investigate the optical and electronic properties of the dyes. The studied dyes (excluding the dye containing OH group) displayed three absorption bands within the visible and NIR regions. Low-energy peaks ranged from 498 to 576 nm, corresponding to excitation from ground state to first excited state. Moderate intensity bands appeared at 376 to 418 nm, with the highest energy bands falling within 351 to 384 nm. Ground state oxidation potential values for the dyes were lower than the redox potential of the iodide/triiodide pair. Similarly, excited state oxidation potential values were higher than or equal to the conduction band of TiO2, except for NO2 and CHO containing dyes. Ionization potential values ranged from 6.24 eV to 6.40 eV, while electron affinity values were within 1.21 eV to 2.74 eV. Chemical potential values ranged from 3.75 to 4.57 eV, and chemical hardness of the dyes fell between 1.83 to 2.54 eV. The proposed cyano-based anchoring groups show promising potential for enhancing DSSC performance. [ABSTRACT FROM AUTHOR]

A method for the grafting of unsymmetrical A2BC-type 5,15-bis(4-butoxyphenyl)-10-(4-carboxyphenyl)-20-(phenanthrenoimidazolyl)-porphyrin onto the surface of nanostructured aluminum oxyhydroxide modified with a single SiO2 layer (NAOM) was successfully developed. A straightforward procedure towards surface modification of NAOM allowed us to prepare a new porphyrin-containing hybrid material. The obtained 3D heterostructure was extensively characterized using XPS, TEM and diffuse reflectance spectroscopy. Structural and morphological peculiarities of the inorganic support before and after the immobilization procedure were studied and discussed in detail. The stability of the material against leaching and the porphyrin immobilization ratio ca. 14% by weight were also revealed. [ABSTRACT FROM AUTHOR]

Background: In the present work, DFT and time-dependent DFT calculations were performed to investigate the role of anchoring groups on the photophysical properties and reveal structure-property correlations of triphenylamine (TPA) derivatives. The selected anchoring groups are tetrazole, acrylamide, hydantoin, and rhodanine. Results: Our results show that the different anchoring groups employed alter the planarity, intramolecular charge transfer properties, and HOMO-LUMO gap and hence influence the optoelectronic properties of the dyes. Although all molecules fulfill the basic requirements with suitable energy levels, band gap, absorption, and charge transfer properties, the dye with rhodanine acceptor (TPA4) was the most promising candidate due to its lowest HOMO-LUMO gap, red-shifted highest λmax absorption value, better ICT pattern, low total reorganization energy, and good electron injection properties. Overall, it is anticipated that the results of this investigation will point to new avenues for the experimental fabrication of remarkably effective metal-free organic dyes for solar cell applications. [ABSTRACT FROM AUTHOR]

Context: In this study, new visible light harvesting dyes (MBR1–MBR5) have been designed as efficient materials with silyl based anchoring abilities on semiconducting units for future dye-solar cells applications. Their unique molecular structures of novel D-π-ASemiconductor type were evaluated thoroughly by density functional theory (DFT) calculations. To enhance the optical performance in visible region, a novel dye structure (MBR) was derived from the chemical structure of mordant black (MB) dye with electron acceptor semiconducting units (MBR1–MBR5). Methods: The Coulomb-attenuating Becke, 3-parameter, Lee–Yang–Parr (CAM-B3LYP) functional, which had a hybrid and long-range correlation with 6-31G + (d,p), generated a λ max (683 nm) that was very comparable to its experimental value (672 nm). The energies of highest occupied molecular orbitals (HOMO), lowest unoccupied molecular orbitals (LUMO), and their HOMO–LUMO energy gaps (HLG) were calculated. Their ionization potentials (IP) varied from 5.616 to 8.320 eV, demonstrating their good electron donating trend. The λ max values of dyes displayed a significant red shift from MBR (682 nm) value with range 565–807 nm except MBR1 which was slightly blue shifted. The dye MBR4, which had the smallest HLG (0.23 eV) had the greatest second order nonlinear optical (NLO) response of 144,234 Debye-Angstrom−1. The DFT calculated results provided insight into the creation of new silyl anchoring groups for future DSSCs material designs with increased stability and effectiveness. The goal of the current study is to forecast the development of novel NLO materials with a D-π-ASemiconductor design that use semiconductors as anchoring groups to adhere to a surface. [ABSTRACT FROM AUTHOR]

Strategies to enhance the ratio of the molecular horizontal emitting dipole orientation (Θ∥) for thermally activated delayed fluorescence (TADF) emitters have unlocked the full potential of efficiencies for the evaporated devices, which, however, remain elusive for the solution‐processed ones. Here, a strategic molecular design for solution processable TADF emitters featuring high Θ∥s is proposed by attaching flexible chains ended with bipolar 9,9′‐spirobi[fluorene] subunits as anchoring groups onto TADF emitting core. It's unveiled that the anchoring groups not only enhance the horizontal orientation via enlarging molecular planarity, but also benefit the high photoluminescence in pristine films. The corresponding non‐doped solution processable OLEDs substantiate an unprecedented maximum external quantum efficiency (EQEmax)>30 %. Meanwhile, combining these compounds as TADF sensitizers, and multiple resonance final emitter, solution‐processed OLEDs achieve an EQEmax of 25.6 % with a narrow full width at half maximum of 29 nm. [ABSTRACT FROM AUTHOR]

A method for the grafting of unsymmetrical A2BC-type 5,15-bis(4-butoxyphenyl)-10-(4-carboxyphenyl)-20-(phenanthrenoimidazolyl)-porphyrin onto the surface of nanostructured aluminum oxyhydroxide modified with a single SiO2 layer (NAOM) was successfully developed. A straightforward procedure towards surface modification of NAOM allowed us to prepare a new porphyrin-containing hybrid material. The obtained 3D heterostructure was extensively characterized using XPS, TEM and diffuse reflectance spectroscopy. Structural and morphological peculiarities of the inorganic support before and after the immobilization procedure were studied and discussed in detail. The stability of the material against leaching and the porphyrin immobilization ratio ca. 14% by weight were also revealed.

Novel near-infrared sensitizers with different anchoring groups aiming toward improved stability and efficiency of dye-sensitized solar cells were synthesized. Adsorption of these dyes on the mesoporous TiO2 surface revealed the dye adsorption rate of −CH=CH-COOH (SQ-139) > −CH=C(CN)COOH (SQ-140) > −PO3H2 (SQ-143) > −CH=C(CN)PO3H2 (SQ-148) > −CH=C(CN) PO3H-C2H5 (SQ-157) > −PO3H-C2H5 (SQ-151) > −CH=CH-COOH(−PO3H2) (SQ-162). The binding strength of these dyes on mesoporous TiO2 as investigated by dye desorption studies follows SQ-162 > SQ-143 > SQ-148 > SQ-139 ≫ SQ-157∼SQ-151 ≫ SQ-140 order. The acrylic acid anchoring group was demonstrated to be an optimum functional group owing to its fast dye adsorption rate and better binding strength on TiO2 along with good photoconversion efficiency. Results of dye binding on TiO2 surface demonstrated that SQ-162 bearing double anchoring groups of phosphonic and acrylic acid exhibited > 550 times stronger binding as compared to dye SQ-140 having cyanoacrylic acid anchoring group. SQ-140 exhibited the best photovoltaic performance with photon harvesting mainly in the far-red to near-infrared wavelength region having short circuit current density, open-circuit voltage and fill factor of 14.28 mA·cm−2, 0.64 V and 0.65, respectively, giving the power conversion efficiency of 5.95%. Thus, dye SQ-162 not only solved the problem of very poor efficiency of dye bearing only phosphonic acid while maintaining the extremely high binding strength opening the path for the design and development of novel near-infrared dyes with improved efficiency and stability by further increasing the π-conjugation. [ABSTRACT FROM AUTHOR]

In dye-sensitized solar cells (DSSCs), the dye material plays a crucial role in determining the amount of electrical current obtained, which is the primary outcome of the cell. Therefore, it is crucial to explain the performance of a dye at a molecular level. This work investigates using density functional theory and time-dependent density (DFT and TD-DFT, respectively) four experimentally tested anthanthrene-based dyes abbreviated as D1 to D4. The four dyes differ in their alkyl-substitutions (nonane or 3-ethylheptane) and the number of anchoring groups (one/two cyanoacrylic acid/s). To study the effect of these two structural features, the work involves the calculations of the geometrical structures, electronic and optical properties of isolated forms. In addition, the adsorption behaviour of these dyes on TiO2 clusters was explained. Properties such as the adsorption energies, and electro-optical properties were calculated and discussed.

The present work studies effects of the introduction of phenylene group as the central aromatic group on the structural and electronic properties of polyyne (Pol-[HCN]2Ph) and cumulene (Cum-[H2CN]2Ph) chains with N = 3–8 under ωB97X-D/6-311G** level of theory. Pol-[HCN]2Ph chains have closed singlet ground state, whereas Cum-[H2CN]2Ph chains possess an open shell singlet ground state for all cases except for N = 2 which has a closed shell singlet ground state. Reduction in BLA was seen in Pol-[HCN]2Ph chains for open shell triplet state, while for Cum-[H2CN]2Ph, closed shell singlet showed lower BLA compared to open shell triplet and singlet states. Electron flows from the metal surface to the molecule for all N values of Pol-[HCN]2Ph chains. Except for N = 2, in Cum-[H2CN]2Ph chains, electron is transferred from the metal surface to the molecule. Binding energies with gold cluster increases with chain length for Cum-[H2CN]2Ph chains and decreases with chain length for Pol-[HCN]2Ph chains. [ABSTRACT FROM AUTHOR]

We designed a series of organic dyes based on two triphenylamine units (electron donors), pyrrole/thiophene (π‐bridge) and N‐substituted alkyl thiobarbituric acid (electron acceptors) to construct the D‐π‐A‐D photosensitizer systems. The electronic structures and photophysical properties of the sensitizers were investigated by density functional theory (DFT) and time‐dependent DFT (TD‐DFT). The potential use of the dyes as photosensitizers in DSSCs was explored by calculating the light harvesting efficiency (LHE), electrons driving force injection (ΔGinject), the open‐circuit photovoltage (VOC), and surface interaction with semiconductor (TiO2). From alkyl‐substituted sensitizers, N‐ethyl derivatives TPAA3 and TPAB3 performance for ΔGinject (−1.69 and −1.65 eV) and VOC (1.43, and 1.11 eV) was superior to the other dyes. In addition, the anchoring ability of the N‐substituted alkyl derivatives was higher than the cyanoacrylic dyes. [ABSTRACT FROM AUTHOR]

Comb-like hyperdispersants are widely used for the dispersion of liquid dispersed dyes (LDDs), because of the molecular structure of comb, in which the effective steric hindrance effects provided by polymer side chains and the adsorption force provided by anchoring groups, resulting in the dispersant to be firmly adsorbed on the surface of the dye. However, the mechanism by which the anchoring groups in this dispersant affect the dispersion and stability of LDDs is still unclear. Herein, three types of anchoring group modified comb -like polycarboxylate hyperdispersants were synthesized to explore the effect of anchoring groups on stability and dispersibility, in which the anchoring groups from the monomers of 2-vinylnaphthalene (2-VNP), styrene (St), and 4-vinylbiphenyl (4-VBP). The optimal sand grinding conditions and dispersion stability of the modified hyperdispersants were comprehensively investigated. 2-VNP modified hyperdispersant (DPN) possessed higher grinding efficiency and better dispersion stability than those of St (DPS) and 4-VBP modified hyperdispersants (DPB). The results of atomic force microscope (AFM) and quartz crystal microbalance (QCM) indicated that DPN exhibited higher adsorption force (2.16 mN/m) than that the DPS (0.648 mN/m) and DPB (1.56 mN/m), thereby improving the adsorption strength of dispersants and DDs, stabling the dispersion effect of LDDs. In addition, the dyeing performance of the prepared LDDs on polyester fabric was further investigated. It was found that these LDDs acquired a faster dyeing rate, higher K/S values and rubbing color fastness, and lower chemical oxygen demand (COD) of residual liquid than commercial powder DDs, due to the higher adsorption force on the DDs surface provided good colloidal stability in the high temperatures dye bath. We expect that this study will provide important mechanistic insights into the development of hyperdispersants for LDDs controlled by high adsorption force anchoring groups. [Display omitted] • Synthesis of comb -like anchoring group modified polycarboxylate hyperdispersants. • Measurement of interaction force of modified hyperdispersants with dispersed dyes. • Strong interaction could significantly enhance the grinding efficiency, dispersion stability and dyeing performance. [ABSTRACT FROM AUTHOR]

Design and synthesis of new potent sensitizers are of interest for realization of high-efficiency Dye Sensitized Solar Cells (DSSCs). Modification of the triphenylamine-based dyes by introducing suitable anchoring groups aimed at improvement of optoelectronic properties is attempted in our work. The molecular structure, molecular orbitals and energies, electronic absorption spectra, free energies of electron injection and dye regeneration, chemical reactivity parameters and adsorption to TiO2 semiconductor have been reported. Density functional theory (DFT) and time-dependent DFT (TD-DFT) were used to obtain the reported properties. The results reveal superior optical, electronic properties, chemical reactivity parameters and adsorption energies for the investigated dyes. The findings evince that the dyes featuring heterocyclic anchoring groups could be potential candidates for DSSCs' applications; the new materials are worthy of being investigated experimentally. [ABSTRACT FROM AUTHOR]

The electronic structure and absorption spectra of two D-π-A-type organic dyes with different anchoring groups have been investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The effect of anchoring groups on the electronic absorption of the free dyes on (TiO2)9 has been studied for the two carbazole dyes (MK1 and MK2). Results from DFT calculations indicate that hydroxamic acid anchoring group in MK2 lead to much stronger intermolecular charge transfer and adsorption energies on (TiO2)9 cluster. The effect of four different XC functionals (B3LYP, ωB97xD, M06-2X, and CAM-B3LYP) on the transition energies has been tested in order to explore the valid functional for the studied system. The wavelength values from the ωB97xD/6-31+G** level of theory are in excellent agreement with experimental data so this functional was considered to calculate the electronic absorption of the two studied dyes. The highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and the gap energy (H–L) of the studied dyes are slightly influenced by change of anchoring group. Results reveal that the LUMO energy levels of all studied dyes are higher than the conduction band (CB) of TiO2 (− 4.00 eV). Deprotonation process enhances the efficiency of dye-sensitized solar cells during decreasing adsorption energy of dyes with (TiO2)9 cluster. [ABSTRACT FROM AUTHOR]

Here we report the first theoretical characterization of the interface between the CuGaO2 delafossite oxide and the carboxylic (–COOH) and phosphonic acid (–PO3H2) anchoring groups. The promising use of delafossites as effective alternative to nickel oxide in p-type DSSC is still limited by practical difficulties in sensitizing the delafossite surface. Thus, this work provides atomistic insights on the structure and energetics of all the possible interactions between the anchoring functional groups and the CuGaO2 surface species, including the effects of the Mg doping and of the solvent medium. Our results highlight the presence of a strong selectivity toward the monodentate binding mode on surface Ga atoms for both the carboxylic and phosphonic acid groups. Since the binding modes have a strong influence on the hole injection thermodynamics, these findings have direct implications for further development of delafossite based p-type DSSCs.

Abstract A new series of macrocyclic Ni (II) complexes having indolenine and dibenzotetraaza [ 14 ] annulene (DBTAA) moieties were synthesized and tested for their application as sensitizers in dye - sensitized solar cells (DSSCs). The structures are furnished with anchoring groups of ethyl ester (8a , 8b , and 8c) or carboxylic acid (9c) on the indolenine moiety and hexyloxy (8b) or neopentyloxy (8c , 9c) groups on the DBTAA moiety. The best performance was exhibited by dye 9c , which under constant AM 1.5G solar simulation (100 mW cm−2) using I−/I 3 − electrolyte gave a short-circuit current J sc = 0.43 mA cm−2, an open-circuit voltage V oc = 0.41 V and a fill factor FF = 0.528, corresponding to an overall conversion efficiency of η = 0.093%. This is the first investigation of macrocyclic DBTAA derivatives as sensitizers for DSSCs applications. Graphical abstract Image 1 Highlights • 4 types of novel Ni-DBTAA complexes were prepared and used as sensitizers for DSSC. • Spectroscopic, electrochemical and DFT were conducted to investigate the electron transfer. • The influence of linear and branched alkyl substitutions on the dye performance were investigated. • The COOH anchoring group displayed better cell performance than ethyl ester anchoring group. • This is the first investigation of DBTAA as sensitizers for DSSC. [ABSTRACT FROM AUTHOR]

The design and synthesis of ruthenium tris‐diimine photosensitizers appropriately functionalized to be (i) anchored onto transparent conductive oxides (TCO) and (ii) covalently coupled with a water‐splitting catalyst represents an important target for solar fuel production in dye‐sensitized photoelectrochemical cells (DS‐PECs). In this study, two different synthetic routes to prepare heteroleptic [Ru(4,4′‐(CH2PO3Et2)2‐bpy)2(N^N)](PF6)2 complexes are evaluated, the scope and limitations of the organometallic pathway involving half‐sandwich η6‐arene ruthenium complexes as synthetic intermediates being especially studied. The spectroscopic and electrochemical characterization of a series of novel structures varying by the nature of the third diimine N^N ligand is reported. [ABSTRACT FROM AUTHOR]

Two different copper and gallium arylcorroles have been functionalized using the Vilsmeier–Haack reaction. A further Knoevenagel reaction with cyanoacetic acid was performed on both complexes, affording the desired products with yields above 90 %. The newly synthesized compounds have been thoroughly characterized by a combination of spectroscopic methods, optical analyses, and X‐ray crystallography. Moreover, they have been tested as anchoring groups for the hydrothermal synthesis of ZnO nanoparticles. The morphology of the heterogeneous composites has been studied by SEM, EDS and fluorescence microscopy analyses, thus confirming the presence of the corrole macrocycle in the hybrid material. A new class of corrole complexes bearing a cyanoacetic moiety at the β‐position was obtained in excellent yields through a Knoevenagel reaction. The newly prepared compounds were thoroughly characterized and the peripheral carboxylic moiety was used as an anchoring group in the synthesis of ZnO nanoparticles. [ABSTRACT FROM AUTHOR]

A set of functional SCO systems based on FeII‐2,6‐di(pyrazol‐1‐yl)pyridine (BPP), FeII‐BPP, featuring supramolecular pyrene and fullerene (C60) anchoring groups for nanocarbon materials are designed and synthesized. The pyrene tethered complexes [Fe(L1)2](BF4)2 and [Fe(L2)2](BF4)2 comprise structurally different BPP‐pyrene ligand systems L1 (BPP‐COOR, R = –CH2‐pyrene) and L2 [BPP‐CH2OR, R = –OC(CH2)‐pyrene]. The [Fe(L1)2](BF4)2 complex showed gradual and high temperature SCO (T1/2 = ca. 450 K), whereas the [Fe(L2)2](BF4)2 complex remained trapped in the high spin (HS) state in the 300–5 K temperature range. On the other hand, the bulky fullerene (C60) tethered complex, [Fe(L3)2](BF4)2, is HS at 385 K and showed gradual but incomplete SCO, upon cooling, centered at 208 K. The results compiled in this study indicate the dominant role of intermolecular interactions in tuning/blocking SCO in the studied FeII‐BPP complexes, a fact that needs to be carefully weighed while designing functional‐SCO systems. The role of intermolecular steric interactions in tuning the spin crossover characteristics of FeII‐2,6‐di(pyrazol‐1‐yl)pyridine complexes tethered with supramolecular pyrene and fullerene (C60) anchoring groups for nanocarbon materials is discussed. [ABSTRACT FROM AUTHOR]

Chlorophyll a derivatives were integrated in “all solid-state” dye sensitized solar cells (DSSCs) with a mesoporous TiO2 electrode and 2′,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene as the hole-transport material. Despite modest power conversion efficiencies (PCEs) between 0.26% and 0.55% achieved for these chlorin dyes, a systematic investigation was carried out in order to elucidate their main limitations. To provide a comprehensive understanding of the parameters (structure, nature of the anchoring group, adsorption …) and their relationship with the PCEs, density functional theory (DFT) calculations, optical and photovoltaic studies and electron paramagnetic resonance analysis exploiting the 4-carboxy-TEMPO spin probe were combined. The recombination kinetics, the frontier molecular orbitals of these DSSCs and the adsorption efficiency onto the TiO2 surface were found to be the key parameters that govern their photovoltaic response.

We report on an experimental investigation of transport through single molecules, trapped between two gold nano-electrodes fabricated with the mechanically controlled break junction (MCBJ) technique. The four molecules studied share the same core structure, namely oligo(phenylene ethynylene) (OPE3), while having different aurophilic anchoring groups: thiol (SAc), methyl sulfide (SMe), pyridyl (Py) and amine (NH2). The focus of this paper is on the combined characterization of the electrical and mechanical properties determined by the anchoring groups. From conductance histograms we find that thiol anchored molecules provide the highest conductance; a single-level model fit to current–voltage characteristics suggests that SAc groups exhibit a higher electronic coupling to the electrodes, together with better level alignment than the other three groups. An analysis of the mechanical stability, recording the lifetime in a self-breaking method, shows that Py and SAc yield the most stable junctions while SMe form short-lived junctions. Density functional theory combined with non-equlibrium Green’s function calculations help in elucidating the experimental findings.

[6,6]‐Phenyl‐C61‐butyric acid methyl ester (PC61BM and PC71BM) is an archetypal electron acceptor in organic photovoltaic devices. However, it nucleates and grows to form aggregates or crystallites on a length scale of tens of nanometres to micrometres under thermal aging, which often results in a significant decrease in device efficiency and stability. To overcome this thermally induced performance degradation, many methods have been reported to date such as the introduction of hydrogen, halogen bonding, thermally or photochemically crosslinkable groups onto the fullerene, and the suppression of nucleation and growth of fullerene crystallites under thermal aging has been successfully demonstrated. Even though those methods are highly useful for the suppression of aggregation, we successfully demonstrated another one simple method for the same: Introduction of bulkier groups onto the fullerene, which can act as anchoring group to suppress the aggregation. In an extension of our previous work, quinoxaline (TQT), benzothiadiazole (TBTT) and benzoselenadiazole (TBST) based bulkier groups are linked to the fullerene, denoted as TQT‐C60, TBTT‐C60 and TBST‐C60, respectively, through the 1,3‐dipolar cycloaddition of corresponding azomethine ylides with fullerene. Single junction bulk heterojunction polymer solar cells were fabricated with the configuration ITO/PEDOT:PSS/P3HT:dyad/Ca/Al. The morphological stability of the active layer was monitored by transmission electron microscopy and optical microscopy. Independent of heteroatoms, all the dyads show excellent morphological stability under thermal aging compared to the archetypal acceptor PCBM due to the anchoring of substituent groups. © 2018 Society of Chemical Industry To overcome the aggregation of fullerene derivatives in the active layer of organic photovoltaic devices under thermal aging, many techniques have been reported to date such as the introduction of hydrogen bonding, halogen bonding, thermally and photochemically crosslinkable groups onto the fullerene. Here, we successfully demonstrated another one simple technique for the same: Introduction of bulkier group onto the fullerene, which can act as anchoring group to suppress its aggregation [ABSTRACT FROM AUTHOR]

We describe the synthesis as well as the optical and charge-transport properties of a series of donor-acceptor (D-A) ladder-type heteroacenes. These molecules are stable, soluble, and contain up to 24 fused rings. Structural analyses indicated that the backbones of S10r and Se10r are bent in single crystals. The three 10-ring heteroacenes were functionalized with thiol anchoring groups and used for singlemolecular conductance measurements. The highest conductance was observed for molecular wires containing a benzoselenadiazole (BSD) moiety, which exhibits the narrowest band gap. Multiple charge-transport pathways were observed in molecular wires containing either benzothiadiazole (BTD) or BSD. The conductance is a complex function of both energy gap and orbital alignment. [ABSTRACT FROM AUTHOR]

D-π-A dyes have received a special attention in the field of dye-sensitized solar cells (DSSCs). In this kind of molecules, the acceptor group (A) generally acts as an anchor, enabling the adsorption of the dye onto the metal oxide substrate (TiO2) and providing a good electron injection. The search for new anchors represents a critical factor for the development of improved DSSCs and in recent years has been a very active research field. This mini-review focuses especially on our work on pyridine-derived anchoring groups for D-π-A dyes, with a special regard on the preparation and characterization of three different families of dyes and a critical evaluation of their stability and efficiency. [ABSTRACT FROM AUTHOR]

Abstract: The development of new anchoring groups is important to facilitate effective co‐sensitization in dye‐sensitized solar cells (DSSCs). Herein, stable organic D–π–A dyes that contain new heterocyclic hydantoin‐based anchoring groups have been designed, synthesized, and used in DSSCs. These dye sensitizers were evaluated in terms of their absorption spectra, electrochemical properties, and performance in DSSC devices. Although only one‐third of the amount of hydantoin‐containing dyes adsorbed onto TiO2 relative to their cyanoacrylic‐acid‐containing analogues, they exhibited effective photoexcited electron‐transfer properties. External quantum efficiencies of over 80 % was observed, which were comparable to those of the cyanoacrylic‐acid‐containing dyes. In addition, the new hydantoin‐containing dyes exhibited significant robustness, which could allow improved stability of their corresponding photovoltaic devices under harsh conditions, such as high temperature and humidity. [ABSTRACT FROM AUTHOR]

A reproducible electro-assisted method is proposed to follow the influence of different sulfur-based anchoring groups on the adsorption kinetics and thermodynamics of SAM formation on gold electrodes. This has been made possible thanks to the preparation of several molecules containing various anchoring groups (thiol, thioester, acyclic and cyclic disulfides, thiosulfonate) while preserving the same spacer redox head group. In this paper we focus on the question of a substantial difference between SAMs derived from either alkylthiols or disulfides using cyclic voltammetry. The comparison of equilibrium surface coverage, affinity constant toward gold surface and stability suggest a decisive role of the nature of the anchoring group in the formation of the monolayers. Moreover, a significant difference of the desorption behavior of SAMs on gold, pre-formed from either thiol or disulfide, has clearly been demonstrated. [ABSTRACT FROM AUTHOR]

In this work, two new D-A-π-A perylene dyes featuring with cyanoacrylic acid and 2-(1,1-dicyanomethylene) rhodamine (DCRD) as the electron acceptor/anchoring group, respectively, in combination with a N-annulated perylene electron donor and a quinoxaline auxiliary acceptor were investigated for application in dye-sensitized solar cells (DSCs) and dye-sensitized photocatalytic hydrogen production. The results showed that the sensitizer with cyanoacrylic acid ( YFT-1 ) based DSCs showed a higher conversion efficiency of 7.58% under AM1.5 solar conditions. However, it was interesting that the sensitizer with DCRD ( YFT-2 ) sensitized Pt/TiO 2 photocatalysts displayed a higher rate of H 2 evolution of 83.5 μmol h −1 under visible-light irradiation with wavelength between 420 nm and 780 nm. This may be ascribed to less interface charge recombination and more effective interfacial electron transfer between photo-excited YFT-2 and TiO 2 in aqueous solution. This study demonstrates that YFT-2 containing DCRD anchoring group is a promising candidate to achieve high and stable activity of H 2 production. [ABSTRACT FROM AUTHOR]

• New novel porphyrin dyes were developed with three naphthyl rings and one anchoring group (phenyl carboxylic acid/phenyl hydroxyl group). • A simple condensation methodology for naphthyl porphyrins was reported. • The detailed photophysics and electrochemistry of the dyes to the anchoring group are presented. • The maximum efficiency achieved PCE for ZnNPCA with DCA co-adsorption is 1.85%. Two new Zn(II) porphyrin dyes ZnNPCA and ZnNPHy bearing three naphthyl groups and one carboxyphenyl/hydroxyphenyl anchoring group in an A 3 B meso substitution pattern was synthesized utilizing a mixed condensation approach. The redshifted absorption bands to 427 nm as impacts on the extended conjugation with three naphthyl substituents. Similarly, the emission spectrum also exhibits a redshift than ZnTPP-COOH dye. The anodic shift was found in the reduction potential of the naphthyl dyes with the carboxylic acid anchor (ZnNPCA) , facilitating the more favourable electron injection. Moreover, the naphthyl porphyrin dyes positively interacted with semiconducting TiO 2 , whose binding mode was further established using FT-IR. While interacting with titania, the more broadening absorption spectra exhibit strong electronic coupling and will benefit the electron injection. The high dye loading amount obtained for ZnNPCA dye was 13.1 × 10−8 mol cm2, which is more significant towards light harvesting. DSSC devices were fabricated using porphyrin-sensitized photoanodes. ZnNPCA showed better efficiency than ZnNPHy owing to higher dye loading onto the titania surface. Furthermore, the influence of co-adsorbent DCA on the photovoltaic performance of the fabricated DSSC devices was investigated. As a result, a maximum efficiency of 1.85% was achieved for ZnNPCA/DCA device. In addition, electrochemical impedance spectroscopy results revealed a higher electron lifetime (6.14 ms) for this device, supporting better suppression of back reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

The ancillary ligands 4′-(4-pyridyl)-2,2′:6′,2′′-terpyridine and 4′-(2,3-dihydrobenzo[ b]thiophene)-2,2′-6′,2'-terpyridine were used to synthesize two series of mono- and dinuclear ruthenium complexes differing in their lengths and anchoring groups. The electrochemical and single-molecular conductance properties of these two series of ruthenium complexes were studied experimentally by means of cyclic voltammetry and the scanning tunneling microscopy-break junction technique (STM-BJ) and theoretically by means of density functional theory (DFT). Cyclic voltammetry data showed clear redox peaks corresponding to both the metal- and ligand-related redox reactions. Single-molecular conductance demonstrated an exponential decay of the molecular conductance with the increase in molecular length for both the series of ruthenium complexes, with decay constants of βPY=2.07±0.1 nm−1 and βBT=2.16±0.1 nm−1, respectively. The contact resistance of complexes with 2,3-dihydrobenzo[ b]thiophene (BT) anchoring groups is found to be smaller than the contact resistance of ruthenium complexes with pyridine (PY) anchors. DFT calculations support the experimental results and provided additional information on the electronic structure and charge transport properties in those metal|ruthenium complex|metal junctions. [ABSTRACT FROM AUTHOR]

Two new carboxyethyltin-functionalized polyoxometalates (POMs) were successfully obtained and confirmed with physicochemical and spectroscopic methods including X-ray crystallography. The lowest unoccupied molecular orbitals of both compounds are higher in energy than that of TiO2, and the optical band gaps of these compounds are smaller than that of TiO2. Grafting them onto a TiO2 film created two kinds of novel photoanode materials that showed significantly enhanced photovoltaic and photocurrent responses, as well as improved photoelectrooxidation activities for methanol relative to that shown by a single TiO2 film. Further, P2W15-Co-SnR produced the largest photocurrent by exploring the photoelectric activities of a series of carboxyethyltin POM derivatives. This work provides new insight into the photoelectrochemical functionalization of POM-based organic-inorganic hybrids. [ABSTRACT FROM AUTHOR]

The electrochemical and photophysical properties of a family of conjugated ligands and their iridium(III) cyclometallated complexes are described. They consist of a series of monocationic IrIII bis-2-phenylpyridine complexes with p-phenylethynyl-1,10-phenanthroline ligands of different length. The structure of these ligands includes terminal acetylthiol or pyridine groups, which can provide good electrical contacts between metal electrodes. Cyclic voltammetry, absorption and emission spectroscopy, laser flash photolysis and density functional theory calculations reveal that the high conjugation of the diimine ligand affords small energy gaps between the frontier orbitals. Nevertheless, the nature of the terminal substituents and the extent of the conjugation in the diimine ligand have little influence on the photophysical features at room temperature. The spectroscopic data and theoretical calculations agree that the charge-transfer nature of the emitting excited state is maintained along the series at room temperature, whereas in rigid matrices ligand-centred states also contribute to the low-temperature emission. The good conducting features of the diimine ligands, the small dependence of the HOMO-LUMO (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) gaps of these complexes on the ligands and the charge-transfer nature of the emitting excited state make these complexes promising test beds for the study of photoconducting phenomena in molecular junctions. [ABSTRACT FROM AUTHOR]

Four types of polycarboxylate ether (PCE) superplasticizers with -COO- (C-PCE), -NH3+ (D-PCE), –SO 3 - (S-PCE) and –COOR (H-PCE) were synthesized. Their molecular structures were characterized by Gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectrum (1H NMR). The adsorption behavior of PCEs was investigated by adsorption amount and layer thickness on cement paste without and with montmorillonite (MMT). Time-dependent flowability and rheological properties of paste were measured and the effects of these PCEs on the hydration of paste were examined. Based on the adsorption behavior of PCEs and fresh properties of pastes without and with MMT, the sensitivity of these PCEs to MMT was also assessed. Results show that D-PCE, S-PCE and H-PCE exhibit lower adsorption amounts, but thicker adsorption layer on cement paste than that of C-PCE. S-PCE shows the best dispersion and retention capability, even in the presence of 3% MMT, and has the smallest sensitivity index. However, H-PCE is the worst one. Paste with D-PCE exhibits comparable initial flowability to that of C-PCE, but higher flowability loss. [ABSTRACT FROM AUTHOR]

The synthesis and the photophysical properties of a series of bpy-R2 derivatives L1- L3 (bpy = 2,2′-bipyridine, R represents the substitution at the 4- and 4′-positions of the bpy) are described. R includes phosphonic ester groups as precursors for potent phosphonate anchoring groups, which enable immobilization on transition metal oxide semiconductor surfaces for applications like dye-sensitized solar cells (DSSCs) or dye-sensitized photoelectrosynthesis cells (DSPECs). The ligands L1- L3 differ in the length of conjugated linker units between bpy core and anchoring groups. Phenylene and triazole moieties serve as building blocks for linker elongation. The resulting adjustability of the distance between semiconductor and chromophore represents a viable route to improve cell efficiency, as it will allow tuning of charge carrier recombination and dye aggregation. Furthermore the photophysical studies of the free ligands reveal a pronounced effect of the aryl substitution. The solid-state structures of L1 and L2 are reported within this contribution, enabling the determination of distances between bipyridine nitrogen donor and anchoring group. [ABSTRACT FROM AUTHOR]

A tropolone group has been employed for the first time as an anchoring group for dye-sensitized solar cells (DSSCs). The DSSC based on a porphyrin, YD2-o-C8T, with a tropolone moiety exhibited a power-conversion efficiency of 7.7 %, which is only slightly lower than that observed for a reference porphyrin, YD2-o-C8, with a conventional carboxylic group. More importantly, YD2-o-C8T was found to be superior to YD2-o-C8 with respect to DSSC durability and binding ability to TiO2. These results unambiguously demonstrate that tropolone is a highly promising dye-anchoring group for DSSCs in terms of device durability as well as photovoltaic performance. [ABSTRACT FROM AUTHOR]

In dye-sensitized solar cells (DSSCs), the dye material plays a crucial role in determining the amount of electrical current obtained, which is the primary outcome of the cell. Therefore, it is crucial to explain the performance of a dye at a molecular level. This work investigates using density functional theory and time-dependent density (DFT and TD-DFT, respectively) four experimentally tested anthanthrene-based dyes abbreviated as D1 to D4. The four dyes differ in their alkyl-substitutions (nonane or 3-ethylheptane) and the number of anchoring groups (one/two cyanoacrylic acid/s). To study the effect of these two structural features, the work involves the calculations of the geometrical structures, electronic and optical properties of isolated forms. In addition, the adsorption behaviour of these dyes on TiO 2 clusters was explained. Properties such as the adsorption energies, and electro-optical properties were calculated and discussed. [ABSTRACT FROM AUTHOR]

Copper complexes with different anchoring groups (based on biquinoline ligands with acetylacetone, catechol, hydroxamic acid, phosphonic acid and thiocarboxylic acid groups) have been studied by Density Functional Theory and Time-Dependent Density Functional Theory, also the integral equation formalism of the polarizable continuum model has been extended to the calculation of solvent effects. Maximum absorption wavelength reaches the highest value for the complex with hydroxamic acid as anchoring group but a low oscillator strength; the rest of the complexes fulfill both properties. In general, the molecular orbitals energy levels and the schematic representation of them suppose an appropriate electron transfer between the sensitizer and the semiconductor (TiO 2 ), emphasizing more clearly for the copper complex with the thiocarboxylic acid. Chemical reactivity parameters like chemical hardness shows similitude for all molecular systems; but not so in the case of the electrophilicity index and electroaccepting power. [ABSTRACT FROM AUTHOR]

Abstract: The electroreduction of bromothiophenes on Au and Ag provides a striking model of synergy in electrocatalysis, when a second group specifically interacting with the catalytic surface is present besides the reacting one, providing an auxiliary anchoring effect. The high catalytic activity of Ag for bromobenzene reduction is enhanced in the bromothiophene case. Moreover, Au, having for bromobenzene a much lower and less reproducible catalytic effect than Ag on account of the repulsive effect of its very negative surface charge in the working potential range, approaches Ag activity in the case of 2-bromothiophene, where the anchoring S group is adjacent to the Br group to be cleaved. The beneficial anchoring effect is lower when it has to be shared between two Br leaving groups adjacent to the S group, and becomes negligible in the case of a bromide leaving group in 3-position. [Copyright &y& Elsevier]

Achieving long-term (>3 months) colloidal stability of upconversion nanoparticles (UCNPs) in biologically relevant buffers has been a major challenge, which has severely limited practical implementation of UCNPs in bioimaging and nanomedicine applications. To address this challenge, nine unique copolymers formulations were prepared and evaluated as UCNP overcoatings. These polymers consisted of a poly(isobutylene- alt -maleic anhydride) (PIMA) backbone functionalized with different ratios and types of phosphonate anchoring groups and poly(ethylene glycol) (PEG) moieties. The syntheses were done as simple, one-pot nucleophilic addition reactions. These copolymers were subsequently coated onto NaYF 4 :Yb 3+ ,Er 3+ UCNPs, and colloidal stability was evaluated in 1 × PBS, 10 × PBS, and other buffers. UCNP colloidal stability improved (up to 4 months) when coated with copolymers containing greater proportions of anchoring groups and higher phosphonate valences. Furthermore, small molecules could be conjugated to these overcoated UCNPs by use of copper-free click chemistry, as was done to demonstrate suitability for sensor and bioprobe development.

Anchoring groups are extremely important in controlling the performance of dye-sensitized solar cells (DSCs). The design and characterization of sensitizers with new anchoring groups, in particular non-carboxylic acid groups, has become a recent focus of DSC research. Herein, new donorπacceptor zincporphyrin dyes with a pyridine ring as an anchoring group have been designed and synthesized for applications in DSCs. Photophysical and electrochemical investigations demonstrated that the pyridine ring worked effectively as an anchoring group for the porphyrin sensitizers. DSCs that were based on these new porphyrins showed an overall power-conversion efficiency of about 4.0 % under full sunlight (AM 1.5G, 100 mW cm−2). [ABSTRACT FROM AUTHOR]

We, herein, explore the potential use of new anchoring groups for the development of hybrid organic-inorganic materials and more specifically for the chemisorption of dyes in dye-sensitized solar cells. The structural and the electronic properties of four different compounds (the 1,2-benzenediole-, catechol-, the pentane-2,4-dione (acetylacetone), and the corresponding thio derivatives) adsorbed on a {100} clean ZnO surface were investigated by the means of density functional theory in a periodic framework. Subsequent-harmonic-infrared (IR) spectral calculations of the adsorbed and isolated systems pointed out that the adsorption process may be followed by IR techniques. From our analysis, all anchoring groups seem to be suitable as anchoring groups in hybrid devices both from a structural and electronic point of view, although additional requirements may be important for specific applications. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 [ABSTRACT FROM AUTHOR]

Abstract: The design and synthesis of an asymmetrical zinc phthalocyanine sensitizer modified with a catechol anchoring group is reported. The performance of this sensitizer was evaluated in a dye-sensitized solar cell. A strong interaction between the catechol dye and TiO2 (with the formation of a five-membered charge-transfer complex) was evidenced by a strong shift in the Q-band of the ZnPc-Cat from 680 nm in solution to 750 nm on TiO2, along with an appreciable absorption tail extending to ∼1000 nm. The fabricated solar cell containing the phthalocyanine sensitizer showed relatively high light-to-electron conversion efficiency (η = 0.92%), considering that few catechol dyes exceed η = 0.7% in dye-sensitized solar cells. Values of Isc  = 2.53 mA cm−2 and Voc  = 540 mV were obtained, referring to a standard N719 cell (η = 6.46%). A comparison of zinc phthalocyanine sensitizers bearing different anchoring groups affirmed the superiority of carboxylate groups relative to those bearing catechol groups in terms of cell performance. [Copyright &y& Elsevier]