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Background Self-assembly monolayers (SAMs) had been used widely to tailor the surface properties; and alkanthiols were the most common molecules which have been intensively studied. However, the assembly behavior of amine molecules and the characteristics of the SAMs are not well understood. Method In this study, dodecylamine (DDA) is used as a model molecule to study the self-assembly behavior of amine molecules from HClO4 solution onto an Au(111) surface. The adsorption process and the SAM characteristics are studied via cyclic voltammetry (CV), in-situ surface-enhanced infrared absorption spectroscopy (SEIRAS) and scanning tunneling microscopy (STM). Significant findings The CV spectra show that the current densities of Fe+2/Fe+3 redox reaction decrease slightly after the treatment of DDA, implying the formation of a DDA adlayer. The in-situ SEIRAS spectra demonstrate that the adsorption of DDA performed slowly. These results imply a weak interaction of DDA with the gold surface. The STM observation in the HClO4 solution demonstrates that the adsorbed molecules arranged in an orderly manner, forming a flat-lying orientation. The lift-off orientation commonly found for thiol molecules doesn't occur for the DDA adlayer. On the basis of this study, the self-assembly ability of DDA on a gold surface is confirmed, and a weak DDA-Au interaction is verified.

The mechanism of photocatalytic biomass reforming for H2 production is far from fully understood. This study uses functionalized graphene dots with Pt-cocatalyst to reform cellulose in an alkaline ...

A new carbon nanotube (CNT) function is proposed herein for dye-sensitized solar cell (DSSC) applications. In this study, single-wall CNT is used as a treating agent to conventional liquid electrol...

Solid-oxide electrolytes (SEs) are an alternative to using conventional organic liquid electrolytes for lithium ion batteries (LIBs) and offer solutions to the challenges associated with safety and energy density. However, SE-based LIBs suffer from high interfacial resistance between the electrolyte and electrodes. In this study, we develop a gelled poly(acrylonitrile-co-methyl acrylate) (P(AN-co-MA)) framework to facilitate Li+ transfer across the interface between an SE pellet of garnet-type Li6.75La3Zr1.75Ta0.25O12 (LLZTO) and a LiFePO4 cathode. The gelled polymeric framework exhibits high ionic conductivity and a large Li+ transference number (tLi+) of 0.67 that results from the synergy between the nitrile and acrylate functionalities and minimizes the formation of ion–solvent clusters and mobility of PF6− anions. The large tLi+ characteristic is advantageous for forming a junction with SEs featuring a unity tLi+ and suppressing polarization caused by PF6− accumulation. When coupled with the LLZTO pellet, the gel polymer electrolyte may exhibit collimated Li+ transport that suppresses Li-dendrite formation. The resulting Li|LLZTO|LiFePO4 battery demonstrates outstanding capacity (e.g., 154 mA h g−1 at 0.1 mA cm−2 and 25 °C), high rate retention, and excellent cycling stability. The present study demonstrates that the gelled P(AN-co-MA) framework acts an ideal interface between the SE and cathode for fabricating quasi-solid LIBs.

Power generation in indoor environments is the next step in dye-sensitized solar cell (DSSC) evolution. To achieve this goal, a critical recombination route which is usually inhibited by the TiCl4-...

A graphene oxide sponge (GOS) is prepared and utilized as a nanofiller (NF) of an iodide liquid electrolyte for dye-sensitized solar cell (DSSC) application. The concentration effects of the GOS NFs on the conductivity of the electrolyte, and the performance of the DSSCs are studied. The results indicate that the inclusion of GOS NFs markedly enhances the conductivity of the liquid electrolyte. The electrochemical impendence spectroscopy (EIS) analysis shows that the presence of GOS NFs may increase the recombination resistance (Rct) at the photoelectrode/electrolyte interface and, furthermore, decreases the charge transfer resistance at the Pt counter electrode/electrolyte interface (Rpt). Therefore, the current density (Jsc), open circuit potential (Voc), and fill factor (FF) of the DSSCs can be improved by controlling the concentration of GOS NFs. In this study, the DSSC with 0.50 wt% GOS NFs can achieve the highest energy conversion efficiency of 9.44%, which is higher than that obtained for the corresponding cell without GOS NFs (8.84%).

A graphene oxide sponge (GOS) is utilized for the first time as a nanofiller (NF) in printable electrolytes (PEs) based on poly(ethylene oxide) and poly(vinylidene fluoride) for quasi-solid-state dye-sensitized solar cells (QS-DSSCs). The effects of the various concentrations of GOS NFs on the ion diffusivity and conductivity of electrolytes and the performance of the QS-DSSCs are studied. The results show that the presence of GOS NFs significantly increases the diffusivity and conductivity of the PEs. The introduction of 1.5 wt % of GOS NFs decreases the charge-transfer resistance at the Pt-counter electrode/electrolyte interface (Rpt) and increases the recombination resistance at the photoelectrode/electrolyte interface (Rct). QS-DSSC utilizing 1.5 wt % GOS NFs can achieve an energy conversion efficiency (8.78%) higher than that found for their liquid counterpart and other reported polymer gel electrolytes/GO NFs based DSSCs. The high energy conversion efficiency is a consequence of the increase in both...

In this study, highly efficient printable electrolytes (PEs) were prepared for a quasi-solid-state dye-sensitized solar cell (QS-DSSC). A liquid electrolyte based on iodide/triiodide redox couples and 3-methoxypropionitrile (MPN) was utilized to prepare the PEs. Poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) were employed as solidifying agents to optimize the properties of the PEs. Moreover, TiO2 nanofillers (NFs) were added to the PEs to enhance the performance of the DSSCs. The results indicate that a PE based on a PEO/PMMA ratio of 7/3 was optimal for efficient printing. The energy conversion efficiency of the DSSC achieved by using this PE was 8.48%, which was higher than the efficiencies of the cell using only PEO PE (7.63%) and liquid-cells (8.32%). This was mainly due to the increase in the electrolyte conductivity and charge transfer resistance at the photoelectrode/electrolyte interface of the DSSC. The presence of 10 wt% TiO2 NFs in the PEs increased the efficiency of the QS-DSSC to 9.12%. The sub-module cell fabricated by using the PE with TiO2 NFs achieved an efficiency of 6.78%. The PE based DSSC exhibited stable long-term efficiency during thermal aging at 60 °C.

Reducing the photocatalyst size to induce quantum confinement increases the interactive overpotential of photogenerated charges, but the consequent bandgap widening is detrimental to light harvesting. This study exploits quantum confinement and the chemical modification advantages of graphene-based materials to produce photocatalysts, nitrogen-doped graphene-oxide dots (NGODs) of 3–12 nm, for the hydrogen evolution reaction (HER). The NGODs exhibit quantum confinement characteristics by emitting size-dependent photoluminescence. The amino/amide functionalities at the peripheries of the NGODs donate their nitrogen lone-pair electrons to conjugate with graphitic π-orbital electrons, thereby lifting the valence band maximum to narrow the bandgap. Additionally, the orbital conjugation delocalizes the photogenerated charges and prolongs their lifetimes. The smallest (3 nm) NGOD, which has a high amino/amide content and a high conduction band minimum, generates high HER overpotential and high apparent quantum yield (25%) under monochromatic 420 nm illumination. Large NGODs, which have a small bandgap, can be used in a tandem design to expand the applicable solar spectrum. Our study demonstrates the superiority of graphene-based materials as photocatalysts by presenting the synergy between quantum confinement and chemical modification that improves photoenergy conversion.

Cyclic voltammetry (CV) and in-situ Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS) are used to study the adsorption behavior of an electroplating additive, 3,3 thiobis-(1-propanesulfonic acid sodium salt) (TBPS), on a polycrystalline Au(111) surface. The effects of the applied potentials on the adsorption behavior of TBPS are investigated and compared to that obtained by in-situ scanning tunneling microscopy (STM) in a previous work. The results show that TBPS molecules can adsorb on the Au surface at 0.05 V (RHE) and approach an equilibrium state after ca. 200 sec. For the IR spectrum detected in the air, the most pronounced peaks of TBPS are symmetric S O (ss-SO) and asymmetric S O (as-SO) stretching modes. Upon adsorption on the Au surface, the ss-SO peak still keeps a sharp and intense shape, while the as-SO peaks appear as a broad peak with much lower intensity. Since the ss-SO vibration mode is parallel to the long molecular axis, these results imply that the TBPS molecules mainly adsorb with a lift-up conformation at 0.05 V. With the increase in electrode potential, the ss-SO peak intensities first increase slightly due to further adsorption of the TBPS, and then, decrease steadily, ascribing to a conformation change of adsorbed TBPS molecules from an upright to a lie-down orientation. On the contrary, the as-SO band intensity first stays constant, and then, increases with increasing potential, consistent with the inference of the conformation change. Accompanying the adsorption and conformation change in the TBPS molecules, the peak corresponding to the bending mode of the adsorbed water δ(HOH) reflects that water molecules move away from the surface when TBPS molecules are adsorbed at low potentials, but will become closer again as the molecular conformation shifts to a lie-down orientation. The adsorption behavior of TBPS with respect to the potential change is reversible.

A facile and cost-effective method is proposed herein to fabricate highly electrocatalytic carbon black/copper sulfide (CB/CuXS) composite counter electrodes for quantum-dot-sensitized solar cells (QDSSCs). In brief, mesoporous CB thin films and copper salts are first deposited on FTO substrates by a spin-coating process; a sulfidation treatment is then conducted to facilitate accumulations of CuXS catalysts in the mesoporous structure. Experimental results illustrate that during the sulfidation, an ion exchange reaction and a reduction of Cu(II) to Cu(I) take place simultaneously, and that the obtained CuXS catalyst possesses a nonstoichiometric phase. The electrochemical properties of the resultant composite films are carefully investigated. The results show that the electrocatalytic activity of the CB/CuXS films related to the polysulfide redox reaction is much superior to that of common platinum. Compared to a solar cell equipped with a solution-processed CuS counter electrode, the QDSSC using a composite film prepared only by a single spin-coating displays similar photovoltaic performance. Furthermore, increasing the coating times can lead to improvements both in the electrocatalytic activity of the CB/CuXS films and in the cell performance of the relevant QDSSCs. When CdS/CdSe sensitizers are employed, the QDSSC using a CB/CuXS counter electrode fabricated with three coating times demonstrates a conversion efficiency of 5.62% under 1 sun irradiation.

While carbon black (CB) is an ordinary, commercial and low-cost carbonaceous material, it displays great potential as an alternative to noble metals and conductive polymers in terms of a counter electrode catalyst for dye-sensitized solar cells (DSSCs) using a Co(bpy)32+/3+ (bpy = 2,2′-bipyridine) redox couple. First, the electrocatalytic activity of this low crystalline material in relation to the cobalt-based redox reaction is carefully studied. The experimental results show that both the heat treatment and the amount of CB loading are key parameters affecting the electrochemical behavior of the resultant CB thin films. A well-prepared CB thin film exhibits better electrocatalysis than sputtered platinum does. This CB film demonstrates its ability to replace common platinum as an efficient counter electrode in DSSCs using a Co(bpy)32+/3+ electrolyte. This material is even more suitable than platinum for fabrication of semitransparent counter electrodes for bifacial photovoltaic applications. Most importantly, a highly efficient Y123-sensitized solar cell is assembled using a CB thin film, revealing a power conversion efficiency of 8.81% without any striking mass transport obstruction. The feasibility of this cost-effective CB material for utilization in DSSCs is definitely verified.

Sodium acetate (NaAc) is utilized as an additive in cationic precursors of the successive ionic layer adsorption and reaction (SILAR) process to fabricate CdS quantum-dot (QD)-sensitized photoelectrodes. The effects of the NaAc concentration on the deposition rate and distribution of QDs in mesoporous TiO 2 films, as well as on the performance of CdS-sensitized solar cells are studied. The experimental results show that the presence of NaAc can significantly accelerate the deposition of CdS, improve the QD distribution across photoelectrodes, and thereby, increase the performance of solar cells. These results are mainly attributed to the pH-elevation effect of NaAc to the cationic precursors which increases the electrostatic interaction of the TiO 2 film to cadmium ions. The light-to-energy conversion efficiency of the CdS-sensitized solar cell increases with increasing concentration of the NaAc and approaches a maximum value (3.11%) at 0.05 M NaAc. Additionally, an ionic exchange is carried out on the photoelectrode to transform the deposited CdS into CdS 1−x Se x ternary QDs. The light-absorption range of the photoelectrode is extended and an exceptional power conversion efficiency of 4.51% is achieved due to this treatment.

This study proposes incorporating nitrogen-doped graphene oxide dots (NGODs) with graphene oxide (GO) sheets to form a stable and effective NGOD:GO composite for photocatalytic H 2 production through water splitting under visible light illumination. Although Pt-deposited NGOD catalysts were active in the photocatalytic H 2 production reaction, they were only moderately stable. Introducing GO sheets in light-absorbing NGODs effectively mediated the transfer of photogenerated electrons from the NGODs to the GO sheets. This vectorial electron transfer, confirmed by a photoluminescence spectroscopy analysis, led to the relocation of the reaction sites from the NGODs to the GO sheets, protecting the NGODs from attack by reaction intermediates. Moreover, the GO sheets acted as an electron sink, facilitating charge separation in the NGODs. When 3 wt% Pt was deposited on the developed NGOD:GO catalyst, the catalyst steadily catalyzed H 2 production from a 10 vol% aqueous solution of triethanolamine under visible light illumination for 96 h, unlike a NGOD catalyst that exhibited an activity decay of 50% within 96 h. The apparent quantum yield of H 2 under 420-nm light irradiation was 16.0%, demonstrating the high activity of the NGOD:GO catalyst.

Cyclic voltammetry (CV) and in situ scanning tunneling microscopy (STM) are used to study the electrodeposition of copper on an ordered Au(111) electrode modified with mercaptoacetic acid (MAA) in 0.1 M H 2 SO 4 + 0.1 mM CuSO 4 . A CV experiment with potential ramping at 5 mV/s from 0.4 to 0 V (vs. Ag/AgCl) results in a monolayer of Cu on this electrode, demonstrating a minor effect of MAA on Cu deposition, an atypical behavior for a thiol modifier on gold electrode. The MAA-modified Au(111) is imaged by STM, which reveals ordered structures on atomically smooth terraces punctured by steps and pits one atom deep. Cu deposition starts at these defective sites and grows to the entire electrode. The MAA modifier prompts uniform Cu deposition, leading to a smooth Cu film on Au(111). On top of the Cu film there is a major striped phase due to MAA molecules and a minor Moire pattern due to bisulfate anions. These ordered surface structures suggest a crystalline Cu substrate, possibly a face-centered cubic (fcc) structure with its (111) plane lying parallel to the Au(111) substrate. Triangular Cu blocks with their apexes pointing in opposite directions are observed, which implies twinned fcc Cu crystallites. Anodic stripping of the Cu deposit restores the MAA adlayer with a notable amount of defects in the film, which implies a simultaneous loss of MAA and Cu.

The use of gel polymer electrolytes (GPEs) in electric double layer capacitors (EDLCs) is limited by the liquid injection assembly line currently used in EDLC manufacturing. This paper proposes a postinjection gelated GPE, which can be synthesized by mixing a polymer blend of poly(acrylonitrile-co-methyl acrylate) and poly(ethylene glycol) (i.e., PANMA:EG) with a conventional liquid electrolyte (LE). The as-synthesized GPE is in liquid state and can be applied in the liquid injection assembly line. The gelation time can be tuned by varying the composition of the polymer blend. The functionalities on the polymer chains facilitate the dissociation of ion pairs and suppress the formation of ion–solvent complexes; thus, the GPE has an ionic conductivity that is three times that of the LE. Under polarization for dielectric analysis, the GPE exhibits high storage permittivity and low loss permittivity because of its swift ion motion and polymeric dipole orientation. Owing to its superior permittivity performance, the resulting GPE-EDLC outperforms the LE-EDLC in terms of the ultimate capacitance, rate capability, and charge–discharge cycling stability. The postinjection gelation feature and outstanding permittivity characteristics indicate the suitability of this GPE in industrial-scale assembly lines and practical applications.

This study uses graphene oxide quantum dots (GOQDs) to enhance the Li+ -ion mobility of a gel polymer electrolyte (GPE) for lithium-ion batteries (LIBs). The GPE comprises a framework of poly(acrylonitrile-co-vinylacetate) blended with poly(methyl methacrylate) and a salt LiPF6 solvated in carbonate solvents. The GOQDs, which function as acceptors, are small (3-11 nm) and well dispersed in the polymer framework. The GOQDs suppress the formation of ion-solvent clusters and immobilize PF6- anions, affording the GPE a high ionic conductivity and a high Li+ -ion transference number (0.77). When assembled into Li|electrolyte|LiFePO4 batteries, the GPEs containing GOQDs preserve the battery capacity at high rates (up to 20 C) and exhibit 100% capacity retention after 500 charge-discharge cycles. Smaller GOQDs are more effective in GPE performance enhancement because of the higher dispersion of QDs. The minimization of both the ion-solvent clusters and degree of Li+ -ion solvation in the GPEs with GOQDs results in even plating and stripping of the Li-metal anode; therefore, Li dendrite formation is suppressed during battery operation. This study demonstrates a strategy of using small GOQDs with tunable properties to effectively modulate ion-solvent coordination in GPEs and thus improve the performance and lifespan of LIBs.

Fluorescent graphene oxide dots (GODs) are environmentally friendly and biocompatible materials for photoluminescence (PL) applications. In this study, we employed annealing and hydrothermal ammonia treatments at 500 and 140 °C, respectively, to introduce nitrogen functionalities into GODs for enhancing their green-color PL emissions. The hydrothermal treatment preferentially produces pyridinic and amino groups, whereas the annealing treatment produces pyrrolic and amide groups. The hydrothermally treated GODs (A-GODs) present a high conjugation of the nonbonding electrons of nitrogen in pyridinic and amino groups with the aromatic π orbital. This conjugation introduces a nitrogen nonbonding (nN 2p) state 0.3 eV above the oxygen nonbonding state (nO 2p state; the valence band maximum of the GODs). The GODs exhibit excitation-independent green-PL emissions at 530 nm with a maximum quantum yield (QY) of 12% at 470 nm excitation, whereas the A-GODs exhibit a maximum QY of 63%. The transformation of the solvent relaxation-governed π* → nO 2p transition in the GODs to the direct π* → nN 2p transition in the A-GODs possibly accounts for the substantial QY enhancement in the PL emissions. This study elucidates the role of nitrogen functionalities in the PL emissions of graphitic materials and proposes a strategy for designing the electronic structure to promote the PL performance.

A new mechanism is proposed against the Grotthuss-type exchange reaction, to interpret the TiO2 nanofiller effect in quasi-solid-state dye-sensitized solar cells. Generally, the inclusion of TiO2 nanofillers in a polymer gel electrolyte causes an enhanced diffusion coefficient and a reduced charge transfer resistance at the electrolyte/counter-electrode interface, thereby improving the photovoltaic performance of the corresponding solar cell. Herein, liquid electrolytes are treated by TiO2 nanoparticles, and the resultant electrolytes yield similar effects on both the electrolyte properties and cell performance. This result suggests a facilitated movement of the triiodide species; however, it cannot be elucidated by the Grotthuss-type mechanism, because of the absence of nanoparticles in such liquid electrolytes. The X-ray photoelectron spectroscopy analysis shows that the TiO2 particles can adsorb iodide ions through their acidic surfaces. The adsorption of iodide ions leads to negatively charged surfaces, which further induces attraction to cations. As a result, cation concentrations in the electrolyte are reduced, and furthermore, the triiodide species can move more easily owing to the attenuated electrostatic interaction with cations. This mechanism is considered to be a dominant reason for the TiO2 nanofiller effect in quasi-solid-state dye-sensitized solar cells.

A novel copolymer, poly(acrylonitrile- co -vinyl acetate) (PAN-VA), is used as the solidification agent to prepare solid-state redox electrolytes for dye-sensitized solar cell (DSSC) applications. TiO 2 nano-particles are used as the fillers to enhance the performance of the solid electrolytes. Furthermore, to improve the penetration of solid electrolytes in the mesoporous TiO 2 matrixes, an external pressure is applied on the electrodes during the solvent evaporation process. The results show that the ionic conductivities of the solid-state electrolytes are comparable with those of gel electrolyte, indicating that the PAN-VA matrix itself may contribute to the charge transfer through the Grotthuss charge transfer mechanism. Based on the temperature-controllable viscosity of the polymer electrolytes, as well as the effect of an applied force, the solid electrolyte can penetrate well in the TiO 2 film, making good contact with the photoelectrode. It is also found that the introduction of TiO 2 fillers does not affect the conductivity of the electrolyte, but greatly enhance the charge transfer at the interface of the electrolyte and Pt counter electrode. On based of the high performance of the electrolyte system, an energy conversion efficiency of 8.65% is achieved for the solid-state DSSC.

The adsorption and self-assembly behaviors of a carboxyl-group-terminated alkanethiol, 11-mercaptoundecanoic acid (MUA), on Au(111) electrodes in an electrochemical system are studied using in situ scanning tunneling microscopy. The effect of applied potential on the phase evolution of the MUA adlayer is investigated and compared with those reported for alkanethiols with various terminal groups. The results show that the MUA molecules initially adsorb in a lie-down orientation, organizing into ordered domains with a stripe structure. With further adsorption of MUA molecules, the alkyl chains lift off from the substrate, forming a more condensed phase with an arrangement of (√3 × √3). This phase evolution is similar to those reported for other alkanethiols. However, the adsorption process of MUA is much slower and a disordered transition phase (γ phase) exists between the stripe and saturation phases. The γ phase converts back to the stripe phase when the electrode potential is shifted from 0.2 to 0.4 V, f...

Au(111) electrodes have been modified with self-assembled monolayers (SAM) of 3-mercapto-1-propanesulfonic acid (MPS) and used as a substrate for Cu electrodeposition. Aqueous plating solutions contained 0.1 M H2SO4, low Cu concentrations (≤80 μM), and, optionally, 1.4 mM Cl ions. The deposition process was characterized by cyclic voltammetry (CV) and in-situ scanning tunneling microscopy (STM) as a function of the electrode potential. At potentials positive of Cu growth (≥0.7 VRHE), freshly modified electrodes are covered by an ordered (5√3 × √21) MPS adlayer (α) both in Cl-free and Cl-containing electrolytes. The α adlayer becomes disordered at more negative potentials prior to the onset of Cu deposition (≤0.65 VRHE). In the potential regime of Cu underpotential deposition (UPD) (≈0.2–0.65 VRHE), the surface morphology strongly depends on the presence of Cl. In the absence of Cl, a transient, ordered Cu/MPS adlayer phase (δ) forms via 2D growth and covers the entire Au(111) surface. Subsequently, the δ ...

A high-performance quantum dot-sensitized solar cell (QDSSC) is reported, which consists of a TiO2/CuInS2-QDs/CdS/ZnS photoanode, a polysulfide electrolyte, and a CuS counter electrode. The sensitization process involves attaching presynthesized CuInS2 QDs (3.5 nm) to a TiO2 substrate with a bifunctional linker, followed by coating CdS with successive ionic layer adsorption and reaction (SILAR) and ZnS as the last SILAR layer for passivation. This process constructs a sensitizing layer that comprises CdS nanocrystals, closely packed around the earlier-linked CuInS2 QDs, which serve as the pillars of the layer. The CuS counter electrode, prepared via successive ionic solution coating and reaction, has a small charge transfer resistance in the polysulfide electrolyte. The QDSSC exhibits a short-circuit photocurrent (Jsc) of 16.9 mA cm−2, an open-circuit photovoltage (Voc) of 0.56 V, a fill factor of 0.45, and a conversion efficiency of 4.2% under one-sun illumination. The heterojunction between the CuInS2 QDs and CdS extends both the optical absorption and incident photon conversion efficiency (IPCE) spectra of the cell to a longer wavelength of approximately 800 nm, and provides an IPCE of nearly 80% at 510 nm. The high TiO2 surface coverage of the sensitizers suppresses recombination of the photogenerated electrons. This results in a longer lifetime for the electrons, and therefore, the high Voc value. The notably high Jsc and Voc values demonstrate that this sensitization strategy, which exploits the quantum confinement reduction and other synergistic effects of the CuInS2-QDs/CdS/ZnS heterostructure, can potentially outperform those of other QDSSCs.

Self-assembled monolayers (SAMs) of 3,3′-thiobis(1-propanesulfonic acid, sodium salt) (TBPS) on Au(111) electrodes have been characterized by scanning tunneling microscopy and cyclic voltammetry in aqueous perchloric acid solutions. TBPS exhibits an adsorption behavior typically observed for dialkyl sulfides including intact adsorption and low coverage phases with molecules predominantly lying flat on the surface. On the other hand, an untypical chemical bond and well-ordered domains were determined which resemble the characteristics of alkenethiol SAMs. When the adlayer was prepared at its open circuit potential (OCP), a (6 × 3√3) TBPS adlayer phase was observed at potentials E > 0.7 VRHE in TBPS-free electrolyte. At more cathodic potentials, the adlayer transforms irreversible to a disordered phase. In contrast, in situ STM studies in TBPS-containing electrolyte reveal a very complex, potential-dependent adsorption behavior. With increasing electrode potential, the structure of the adlayer transforms in...

The sidewall structure of multi-walled carbon nanotubes (MWNTs) was successfully functionalized with poly(3-hexylthiophene) (P3HT) by a non-covalent bond method. P3HT plays an important role in dispersing MWNTs, and assists them to have a stable existence at the air/water interface. The behavior of mixed MWNT/P3HT monolayer at the air/water interface was investigated after obtaining a homogeneously dispersed solution. The effect of MWNT concentration on the mixed MWNT/P3HT monolayer was investigated using the pressure–area ( π – A ) isotherm, relaxation curve and transmission electron microscopy (TEM). The mixed MWNT/P3HT monolayer was transferred onto a solid substrate using the Langmuir–Blodgett (LB) technique with horizontal or vertical deposition. The multilayer film was delicately fabricated by repeated deposition of the ultra-thin film. Scanning electron microscopy (SEM) images revealed non-uniformity in morphology of the ultra-thin MWNT/P3HT films. The absorption intensity at 250 nm by UV/vis spectroscopy illustrates that a uniform formation of mixed MWNT/P3HT monolayer into multilayer film was successfully obtained by horizontal deposition. The current–voltage characteristic of the ultra-thin MWNT/P3HT film shows that the current increases linearly with the increasing voltage, which indicates that MWNT/P3HT film forms an ohmic contact with gold. And, the electric current was estimated to be mainly contributed by MWNTs.

A self-assembled monolayer (SAM) of 3-mercaptopropyl-trimethyoxysilane (MPTMS) is pre-assembled onto a mesoporous TiO2 film and is used as a surface-modified layer to induce the growth of CdSe QDs in the successive ionic layer adsorption and reaction (SILAR) process. Due to the specific interaction of the terminal thiol groups to CdSe, the MPTMS SAM is found to increase the nucleation and growth rates of CdSe in the SILAR process, leading to a well covering and higher uniform CdSe layer which has a superior ability, compared with the electrode without MPTMS, in inhibiting the charge recombination at the electrode/electrolyte interface. Furthermore, the performance of the CdSe-sensitized TiO2 electrode can further be improved by an additional heat annealing after film deposition, attributable to a better interfacial connection between CdSe and TiO2, as well as a better connection among CdSe QDs. The CdSe-sensitized solar cell prepared by the present strategy can achieve an energy conversion efficiency of 2.65% under the illumination of one sun (AM 1.5, 100 mW cm−2).

Based on the hole-transport characteristic of poly(3-hexylthiophene) (P3HT), self-assembled thin layer of P3HT was employed to modify the Ag anode of a top-emissive polymer light-emitting diodes (T-PLEDs) to enhance the hole-injection from the Ag anode. The experimental results show that introduction of a P3HT thin layer significantly decreases the threshold voltage of a T-PLED. However, only slightly increase of the work function was achieved due to this modification. To increase the work function of the P3HT modified Ag anode (Ag/P3HT), 1-fluoro-2-nitro-4-azidobenzene (FNAB) was introduced into the terminal tail (–C 6 H 13 ) of P3HT thin layer, which leads to a work function increment of 0.23 eV and a further enhancement in the hole-injection. The luminous efficiency achieved by this modified anode (Ag/P3HT/FNAB) is about fourfold higher than the efficiency obtained from the base device.

In situ scanning tunneling microscope (STM) was used to examine the spatial structures of pentacene molecules adsorbed onto a Au(111) single-crystal electrode from a benzene dosing solution containing 16-400 microM pentacene. Molecular-resolution STM imaging conducted in 0.1 M HClO(4) revealed highly ordered pentacene structures of ( radical31 x radical31)R8.9 degrees , (3 x 10), ( radical31 x 10), and ( radical7 x 2 radical7)R19.1 degrees adsorbed on the reconstructed Au(111) electrode dosed with different pentacene solutions. These pentacene structures and the reconstructed Au(111) substrate were stable between 0.2 and 0.8 V [vs reversible hydrogen electrode, RHE]. Increasing the potential to E0.8 V lifted the reconstructed Au(111) surface and disrupted the ordered pentacene adlattices simultaneously. Ordered pentacene structures could be restored by applying potentials negative enough to reinforce the reconstructed Au(111). At potentials negative of 0.2 V, the adsorption of protons became increasingly important to displace adsorbed pentacene admolecules. Although the reconstructed Au(111) structure was not essential to produce ordered pentacene adlayers, it seemed to help the adsorption of pentacene molecules in a long-range ordered pattern. At room temperature (25 degrees C), approximately 100 pentacene molecules seen in STM images could rotate and align themselves to a neighboring domain in 10 s, suggesting that pentacene admolecules could be mobile on Au(111) under the STM imaging conditions of -150 mV in bias voltage and 1 nA in feedback current.

Cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dots (QDs) are sequentially assembled onto a nanocrystalline TiO2 film to prepare a CdS/CdSe co-sensitized photoelectrode for QD-sensitized solar cell application. The results show that CdS and CdSe QDs have a complementary effect in the light harvest and the performance of a QDs co-sensitized solar cell is strongly dependent on the order of CdS and CdSe respected to the TiO2. In the cascade structure of TiO2/CdS/CdSe electrode, the re-organization of energy levels between CdS and CdSe forms a stepwise structure of band-edge levels which is advantageous to the electron injection and hole-recovery of CdS and CdSe QDs. An energy conversion efficiency of 4.22% is achieved using a TiO2/CdS/CdSe/ZnS electrode, under the illumination of one sun (AM1.5,100 mW cm−2). This efficiency is relatively higher than other QD-sensitized solar cells previously reported in the literature.

3-Mercapto-1-propanesulfonic acid (MPS) and bis(3-sulfopropyl) disulfide (SPS) adsorbed on a Au(111) electrode were studied by using in situ scanning tunneling microscopy (STM). Although the adsorptions of MPS and SPS are known to be oxidative and reductive, respectively, on an Au(111) electrode, these two admolecules behave similarly in terms of phase evolution, surface coverage, potential for stripping, and characteristics of cyclic voltammetry. However, different adsorption mechanisms of these molecules result in different structures. Raising electrode potential causes more MPS and SPS molecules to adsorb, yielding ordered adlattices between 0.67 and 0.8 V (vs reversible hydrogen electrode). The ordered adlattices of MPS and SPS appear as striped and netlike structures with molecules adsorbed parallel to the Au(111) surface. Switching potential to 0.9 V or more positive still does not result in upright molecular orientation, possibly inhibited by electrostatic interaction between the end group of -SO(3)(-) and the Au(111) electrode. Lowering the potential to 0.4 V disrupted the ordered adlayer. Stripping voltammetric experiments show that MPS and SPS admolecules are desorbed from Au(111) at the same potential, suggesting that these molecules are both adsorbed via their sulfur headgroups. The S-S bond in SPS is likely broken upon its adsorption on Au(111).

A polysulfide electrolyte considering simultaneously the penetration of the electrolyte in a mesoscopic TiO2 film and the ion dissociation in the solution is developed for application in a CdS-sensitized solar cell (CdS-DSSC). A methanol/water (7:3 by volume) solution was found to be a good solvent for fitting the requirement mentioned above. The optimal composition of the electrolyte, based on the performance of the CdS-DSSCs, was found to contain 0.5 M Na2S, 2 M S, and 0.2 M KCl. By using a photoelectrode prepared after 4 cycles of chemical bath deposition, FTO/TiO2/CdS-4, the efficiency of the CdS-DSSC obtained for this polysulfide electrolyte is 1.15% under the illumination of 100% sun (AM1.5, 100 mW cm−2). This efficiency is less than that obtained using I−/I3− redox couple (1.84%), mainly caused from the smaller values of fill factor and open circuit potential. However, the CdS sensitizer is stable and, furthermore, a much higher short circuit current and IPCE (80%) are obtained by using the polysulfide electrolyte.

An organic solvent, tetrahydrofuran (THF), was employed to modify the Ag anode of a top-emissive polymer light-emitting diode (T-PLED) for improving the hole injection capability and the performance of a T-PLED device. The X-ray photoelectron spectroscope analysis shows that the THF molecules were chemically adsorbed on the Ag surface, forming oxygen-rich species by substrate-catalyzed decomposition. The THF-modification were found to enhance the hole injection on the Ag anode, decrease the threshold voltage, and increase the light intensity and luminous efficiency of a T-PLED device, attributing mainly to the increase of work function of the Ag anode.

A novel method is proposed to prepare an ordered array of pentacene adlayer on a Au(111) electrode by self-organization in benzene solution without using an ultra-high-vacuum (UHV) system. Because of the electron-rich characteristic, the pentacene monolayer acts as a template to incorporate electron-accepting fullerenes, forming a stable C60/pentacene complex adlayer. The adlayer structure was investigated by an in situ scanning tunneling microscopy (STM). Two adsorbed structures, (√31 × √13) and (6 × √31), were observed for the pentacene adlayer. For the C60/pentacene complex adlayer, molecular resolution STM revealed two ordered arrays, (2√3 × 2√3)R30° and “in phase” structures, for the C60 molecules respected to the Au(111) substrate. The complex adlayer is stable between operational potential 0.35 and 0.9 V and is able to be decomplexed by selectively removing the fullerenes through the action of a high tip potential (0.75 V). The STM investigation also confirms that the complexation is performed by f...

In-situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV) were used to study the phase evolution of 11-mercapto-1-undecanol (MUO) adlayer on an Au(111) electrode. The effect of various electrolytes, including HClO4 and H2SO4, on the adsorption behavior was studied. The MUO adsorption was found to initiate mainly at the intersectional corner of herringbone rows of an Au(111) reconstruction structure in both of the electrolytes. The following growth of an adsorbed cluster develops first along the face-centered-cubic (fcc) position of the herringbone structure. In the HClO4 solution, the MUO molecule is first adsorbed in a flat-lying orientation when the dose concentration of MUO is low, growing to an ordered domain of striped structure (β phase) with a molecular arrangement of (12 × √3). When the surface coverage becomes high, the hydrocarbon chains of MUO lift off from the Au(111) plane, forming a more condensed and saturated phase, the φ phase, identified as (√3 × √3)R30°. At a high dose con...

An efficient polymer light-emitting diode (PLED) was fabricated by inserting polyurethane (PU) between a poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) layer and an Al cathode. The electroluminescence (EL) efficiency of the PU-based device can reach 1.27 cd/A, which is much higher than that of a device without PU (0.015 cd/A). The enhanced performance is attributed to both the hole-blocking capacity of the PU layer and the specific interaction between PU and the deposited Al, significantly facilitating the injection of electrons. Furthermore, the electron injection ability of PU-based devices was found to strongly depend on the thicknesses of the PU and Al layers.

In-situ scanning tunneling microscopy (STM), cyclic voltammetry (CV), and infrared reflection-adsorption spectroscopy (IRRAS) have been used to examine the electrodeposition of gold onto Pt(111) electrodes modified with benzenethiol (BT) and benzene-1,2-dithiol (BDT) in 0.1 M HClO4 containing 10 microM HAuCl4. Both BT and BDT were attached to Pt(111) via one sulfur headgroup. STM and IRRAS results indicated that the other SH group of BDT was pendant in the electrolyte. Both BT and BDT formed (2 x 2) structures at the coverage of 0.25, and they were transformed into (square root(3) x square root(3))R30 degrees as the coverage was raised to 0.33. These two organic surface modifiers resulted in 3D and 2D gold islands at BT- and BDT-coated Pt(111) electrodes, respectively. The pendant SH group of BDT could interact specifically with gold adspecies to immobilize gold adatoms on the Pt(111) substrate, which yields a 2D growth of gold deposition. Molecular resolution STM revealed an ordered array of (6 x 2 square root(13)) after a full monolayer of gold was plated on the BDT/Pt(111) electrode. Since BDT was strongly adsorbed on Pt(111), gold adatoms only occupied free sites between BDT admolecules on Pt(111). This is supported by a stripping voltammetric analysis, which reveals no reductive desorption of BDT admolecules at a gold-deposited BDT/Pt(111) electrode. It seems that the BDT adlayer acted as the template for gold deposit on Pt(111). In contrast, a BT adlayer yielded 3D gold deposit on Pt(111). This study demonstrates unambiguously that organic surface modifiers could contribute greatly to the electrodeposition of metal adatoms.

Copper phthalocyanine thin films were prepared by vacuum deposition at various substrate temperatures onto glass and gold. The effects of substrate temperature and material on film morphology and crystalline structure were studied, and the film characteristics were related to their gas-sensing properties for NO2. We find that CuPc films have fine-grain morphology and small degree of crystallization at low substrate temperature (Td=28°C). When Td is elevated to 100°C, fiber-like morphology was observed on both substrates, with orientation mainly parallel to the substrate. At 150–200°C, the fibers grow larger without significant change of orientation on glass, but whisker structures with less order were formed on gold. The fiber-like structure prepared at 100°C has the highest electrical conductivity, which also implies that the stacking axis of the Pc macrocycle is the high conductivity direction. This characteristic also leads to quick response and higher sensitivity of this film to NO2. The effects of substrate temperature on the film characteristics and gas-sensing properties are compared to the heat-annealing effects observed in our previous work.

CdS quantum dots (QDs) were self-assembled onto a mesoscopic TiO2 film and used as a seed layer to induce the nucleation and growth of CdSe in the followed CBD process. The SAM-CdS-QD-layer contributes a TiO2/CdSe interface with superior ability in inhibiting the charge recombination. After improvement by a surface passivation ZnS layer, an energy conversion efficiency of 2.9% was achieved.

Graphite and TiO(2) nanoparticles are used as fillers to prepare a polymer gel electrolyte (PGE) based on I(-)/I(3)(-) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) for dye-sensitized solar cell (DSSC) applications. Graphite nanoparticles (GNP) were proved to be a more efficient filler than TiO(2) in enhancing the charge conductivity of the PGE, decreasing the activation energy for charge transport and inhibiting the charge recombination at the TiO(2)/electrolyte interface. The energy conversion efficiency of a DSSC fabricated using a PGE containing 0.25 wt% of GNP can be increased from 4.69% (without filler) to 6.04%, close to that of a liquid system obtained in this work.

The adsorption of bis-3-sodiumsulfopropyldi-sulfide (SPS) on metal electrodes in chloride-containing media has been intensively studied to unveil its accelerating effect on Cu electrodeposition. Molecular resolution scanning tunneling microscopy (STM) imaging technique was used in this study to explore the adsorption and decomposition of SPS molecules concurring with the electrodeposition of copper on an ordered Pt(111) electrode in 0.1 M HClO(4) + 1 mM Cu(ClO(4))(2) + 1 mM KCl. Depending on the potential of Pt(111), SPS molecules could react, adsorb, and decompose at chloride-capped Cu films. A submonolayer of Cu adatoms classified as the underpotential deposition (UPD) layer at 0.4 V (vs Ag/AgCl) was completely displaced by SPS molecules, possibly occurring via RSSR (SPS) + Cl-Cu-Pt → RS(-)-Pt(+) + RS(-) (MPS) + Cu(2+) + Cl(-), where MPS is 3-mercaptopropanesulfonate. By contrast, at 0.2 V, where a full monolayer of Cu was presumed to be deposited, SPS molecules were adsorbed in local (4 × 4) structures at the lower ends of step ledges. Bulk Cu deposition driven by a small overpotential (η50 mV) proceeded slowly to yield an atomically smooth Cu deposit at the very beginning (5 layers). On a bilayer Cu deposit, the chloride adlayer was still adsorbed to afford SPS admolecules arranged in a unique 1D striped phase. SPS molecules could decompose into MPS upon further Cu deposition, as a (2 × 2)-MPS structure was observed with prolonged in situ STM imaging. It was possible to visualize either SPS admolecules in the upper plane or chloride adlayer sitting underneath upon switching the imaging conditions. Overall, this study established a MPS molecular film adsorbed to the chloride adlayer sitting atop the Cu deposit.

Cyclic voltammetry (CV) and in situ scanning tunneling microscopy (STM) were used to examine four dithiol molecules, including 1,6-hexanedithiol, 1,9-nonanedithiol, 1,2-benzenedithiol, and 1,3-benzenedithiol, adsorbed on well-ordered Pt(111) electrodes in 0.1 M HClO(4). The open-circuit potential (OCP) of Pt(111) electrodes decreased substantially from 0.95 to 0.3 V (versus reversible hydrogen electrode) upon the adsorption of dithol molecules, which indicates that these adsorbates injected electrons into the Pt electrode. For all dithiol molecules, ordered adlattices of p(2 x 2) and (square root 3 x square root 3)R30 degrees were formed when the dosing concentration was lower than 150 microM and the potential of Pt(111) was more negative than 0.5 V. Raising the potential of Pt(111) from 0.1 to 0.4 V or more positive values could transform p(2 x 2) to (square root 3 x square root 3)R30 degrees before it turned disarray. The insensitivity of the structure of dithiol adlayers with their chemical structures was explained by upright molecular orientation with the formation of one Pt-S bond per dithiol molecule. This molecular orientation was independent of the coverage of dithiol molecules, as nucleation seeds produced at the beginning of adsorption were also constructed with p(2 x 2). The triangular-shaped STM molecular resolution suggested 3-fold binding of sulfur headgroup on Pt(111). All dithiols were adsorbed so strongly on Pt(111) electrodes that switching the potential negatively to the onset of hydrogen evolution in 0.1 M HClO(4) or water reduction in 1 M KOH could not displace dithiol admolecules.

Poly(acrylonitrile-co-vinyl acetate) (PAN-VA) is utilized as a gelation agent to prepare gel-state electrolytes for dye-sensitized solar cell (DSSC) applications. Based on the synergistic effect of PAN-VA and TiO(2) fillers in the electrolyte, the gel-state DSSC can achieve a conversion efficiency higher than that of a liquid counterpart. The high performance of the gel-electrolyte is attributed to the in situ gelation property of the gel-electrolyte, the contribution of the PAN-VA to the charge transfer, as well as the enhancement effect of TiO(2) fillers on the charge transfer at the Pt-electrolyte interface. The experimental results show that the efficiencies of the gel-state cells have little dependence on the conductivity of the electrolytes with various contents of PAN-VA, but are closely related to the penetration situation of the electrolyte in the TiO(2) film. For PAN-VA concentrations ≤15 wt%, the electrolyte can be easily injected at room temperature based on its in situ gelation property. For higher PAN-VA concentrations, good penetration of the high viscous electrolyte can be achieved by elevating the operation temperature. By utilizing a heteroleptic ruthenium dye (coded CYC-B11), gel-state DSSCs with an efficiency of above 10% are obtained. Acceleration tests show that the cell is stable under one-sun illumination at 60 °C.

A novel approach to construct organized structures and tunable electronic properties of poly(3-hexylthiophene) (P3HT) monolayers on Au(111) surfaces was developed based on a self-assembly process in a liquid phase. On a bare Au(111) surface, P3HT adsorbs as a monolayer with a randomly oriented and curvy-wire morphology. When the gold surface was pre-modified by an iodine adlayer (I-Au(111)), the passivation effect of iodine decreases the substrate-adsorbate interaction. As a result, P3HT adsorbs as linear chains, stacking and folding into regular arrays of a polymer bundle. By controlling the electrode at more negative potentials, it is able to desorb the iodine adlayer from the substrate. The remaining P3HT adsorbs onto the Au(111) surface directly, retaining a linear and regular arrangement. However, a different electronic structure is imaged by scanning tunneling microscopy (STM). The scanning tunneling spectroscopy (STS) analysis reveals that this molecular image is associated with a 0.16 eV shift of the Fermi level toward HOMO position, indicating a stronger p-doping characteristic of the adlayer. The phenomenon is ascribed to an iodine-induced p-doping reaction which occurs during the desorption of iodine. This work demonstrates that electrode potential and pre-adsorbed halide adlayers can be effectively used to regulate the arrangement and electronic properties of adsorbed molecules on metallic substrates.

Self-assembled monolayers (SAMs) of 6-mercapto-1-hexanol (MHO) on an Au(111) electrode were prepared in an electrochemical system. The adsorption behavior of MHO and the time-dependent organization of the SAM were investigated by in situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV). The results show that a potential higher than 0.28 V (relative to RHE) is required to induce the adsorption of MHO. At 0.28 V, the MHO molecules adsorb in a flat-lying orientation, forming an ordered striped phase with a molecular arrangement of ([Formula: see text]). However, the adlayer is not stable at this potential. The adsorbed striped phase may recover to the herringbone feature of the gold substrate due to the desorption of adsorbed MHO. At a higher potential (0.35 V), the adlayer becomes stable and can undergo a phase evolution from the striped phase to a condensed structure, identified as c([Formula: see text]). This structure can also be described as a c(4 × 2) superlattice of a [Formula: see text] hexagonal adlattice. The surface coverage of the MHO SAM is identical to the saturated structure of an 11-mercapto-1-undecanol (MUO) SAM reported in a previous work, [Formula: see text]. However, the STM image of MHO adlayer shows a modulation in intensity, reflecting the presence of various conformations of adsorbed molecules. This result is attributed to the shorter chain length of MHO, which gives a weaker van der Waals interaction between adsorbed molecules. This effect also results in a higher charge permeability across the adlayer and a lower striping potential to an MHO SAM.

Colloidal cadmium sulfide (CdS) quantum dots (QDs) were prepared and surface modified by mercaptosuccinic acid (MSA) to render a surface with carboxylic acid groups (MSA-CdS). The MSA-CdS QDs were then assembled onto bare TiO(2) mesoporous films using the carboxylic groups/TiO(2) interaction. The TiO(2) film was also surface modified by 3-mercaptopropyl trimethoxysilane (MPTMS) or 3-aminopropyl-methyl diethoxysilane (APMDS) to prepare, respectively, a thiol (-SH) or amino (-NH(2)) terminated surface for binding with the CdS QDs. The experimental results showed that the MPTMS-modified film has the highest adsorption rate and adsorption amount to the CdS QDs, attributable to the strong thiol/CdS interaction. In contrast, the adsorption rate and incorporated amount of the QDs on the bare TiO(2) film are much lower than for the silane-modified films. The incident photon-to-current conversion efficiency (IPCE) obtained for the CdS-sensitized TiO(2) electrode was about 20% (at 400 nm) for the bare TiO(2), 13% for the MPTMS-TiO(2), and 6% for APMDS-TiO(2). The current-voltage measurement under dark conditions reveals a higher dark current on the MPTMS- and APMDS-modified electrodes, indicating a lower coverage ratio of CdS on these TiO(2) films. This result is attributed to the fast adsorption rate of CdS QDs on the bottleneck of a mesopore which inhibits the transport of the QDs deep into the inner region of a pore. For the bare TiO(2) film, the lower incorporated amount of CdS but higher energy conversion efficiency indicates the formation of a better-covered CdS QDs monolayer. The moderate adsorption rate of MSA-CdS QDs using the carboxylic acid/TiO(2) interaction is responsible for the efficient assembly of QDs onto the mesoporous TiO(2) films.

Alcohol, instead of water, was used as a solvent in a chemical bath deposition process for the in situ synthesis of CdS quantum dots onto mesoporous TiO2 films. Due to low surface tension, the alcohol solutions have high wettability and superior penetration ability on the mesoscopic TiO2 film, leading to a well-covered CdS on the surface of mesopores. The CdS-sensitized TiO2 electrode prepared using the alcohol system not only has a higher incorporated amount of CdS but also greatly inhibits the recombination of injected electrons. The efficiency of a CdS quantum-dots-sensitized solar cell prepared using the present method is as high as 1.84% under the illumination of one sun (AM1.5, 100mW∕cm2).

Two methods, coupling self-assembled monolayer and chemical bath deposition (CBD), were utilized to assemble cadmium sulfide (CdS) quantum dots (QDs) onto mesoporous TiO2 films for dye-sensitized solar cell (DSSC) applications. Colloidal CdS QDs were first self-assembled on the TiO2 surface. CBD was then introduced to replenish the incorporated amount and increase the coverage ratio of CdS QDs on the TiO2 surface. The preassembled CdS QDs act as nucleation sites in the CBD process, forming a CdS nanofilm with an interfacial structure capable of inhibiting the recombination of injected electrons. An efficiency as high as 1.35% for the QD-sensitized DSSC was achieved using the present strategy.