A Sulfide/Polysulfide-Based Ionic Liquid Electrolyte for Quantum Dot-Sensitized Solar Cells

Functionalized polyurethane composite gel electrolyte with cosensitized photoanode for higher solar cell efficiency using a passivation layer

Graphene oxide was chemically tagged with thermoplastic polyurethane, chain extended using butanediol to obtain the varying molecular weight of the polymer. Graphene-tagged polyurethane was functionalized using propane sultone to introduce the polar sulphonate groups in the main chain. The chain extension, tagging of GO and functionalization have been verified through spectroscopic techniques such as NMR, FTIR, UV and gel permeation chromatography. Thermal stability and the nature of the interaction were explored through thermal measurements to understand the effect of GO and functionalization. Electrical conduction was improved by the chemical attachment of graphene with the polymer (5.08 × 10^-7 S cm^-1), which further increases through functionalization and subsequent use of the additive (1.07 × 10^-3 S cm^-1) and make them suitable for gel electrolyte, being in the range of semiconductors. Quantum dots of CdS and CdSe were prepared using a capping agent and their characteristic properties and dimensions were worked out for their suitability as active materials in a solar cell. The optical band gap of quantum dots and HOMO/LUMO band structure of functionalized polyurethanes were measured using UV-vis and cyclic voltammetry, and thereby, constructing the overall energy diagrams for a possible combination of materials. Conducting carbon has been incorporated in the gel electrolyte to modulate the conductivity, while the ZnSe layer has been inserted as a passivation layer between the active material and the gel electrolyte. Solar cell devices were fabricated using the suitable materials, through the suitable energy diagram, and found a significantly high power conversion efficiency of 1.71%. The reason behind the improved efficiency is understood from the greater light harvesting behaviour, higher level of conductivity and blocking capacity of the various layered structures to reduce the electron-hole pair recombination.

Cadmium Selenide Quantum Dots for Solar Cell Applications: A Review

Quantum dot-sensitized solar cells (QDSSCs) are significant energy-producing devices due to their remarkable capability to growing sunshine and produce many electrons/holes pairs, easy manufacturing, and low cost. However, their power conversion efficiency (4%) is usually worse than that of dye-sensitized solar cells (≤12%); this is mainly due to their narrow absorption areas and the charge recombination happening at the quantum dot/electrolyte and Ti O 2 /electrolyte interfaces. Thus, to raise the power conversion efficiency of QDSSC, new counter electrodes, working electrodes, sensitizers, and electrolytes are required. CdSe thin films have shown great potential for use in photodetectors, solar cells, biosensors, light-emitting diodes, and biomedical imaging systems. This article reviews the CdSe nanomaterials that have been recently used in QDSSCs as sensitizers. Their size, design, morphology, and density all noticeably influence the electron injection efficiency and light-harvesting capacity of these devices. A detailed overview of the development of QDSSCs is presented, including their basic principles, the synthesis methods for their CdSe quantum dots, and the device fabrication processes. Finally, the challenges and opportunities of realizing high-performance CdSe QDSSCs are discussed and some future directions are suggested.

Recoverable peroxidase-like Fe3O4@MoS2-Ag nanozyme with enhanced antibacterial ability

Antibacterial agents with enzyme-like properties and bacteria-binding ability have provided an alternative method to efficiently disinfect drug-resistance microorganism. Herein, a Fe₃O₄@MoS₂-Ag nanozyme with defect-rich rough surface was constructed by a simple hydrothermal method and in-situ photodeposition of Ag nanoparticles. The nanozyme exhibited good antibacterial performance against E. coli (~69.4%) by the generated ROS and released Ag⁺, while the nanozyme could further achieve an excellent synergistic disinfection (~100%) by combining with the near-infrared photothermal property of Fe₃O₄@MoS₂-Ag. The antibacterial mechanism study showed that the antibacterial process was determined by the collaborative work of peroxidase-like activity, photothermal effect and leakage of Ag⁺. The defect-rich rough surface of MoS₂ layers facilitated the capture of bacteria, which enhanced the accurate and rapid attack of •OH and Ag⁺ to the membrane of E. coli with the assistance of local hyperthermia. This method showed broad-spectrum antibacterial performance against Gram-negative bacteria, Gram-positive bacteria, drug-resistant bacteria and fungal bacteria. Meanwhile, the magnetism of Fe₃O₄ was used to recycle the nanozyme. This work showed great potential of engineered nanozymes for efficient disinfection treatment.

Heavy Chalcogenide-Based Ionic Liquids in Syntheses of Metal Chalcogenide Materials near Room Temperature

This minireview describes two strategically different and unexplored approaches to use ionic liquids (IL) containing weakly solvated and highly reactive chalcogenide anions [E-SiMe3 ]- and [E-H]- of the heavy chalcogens (E=S, Se, Te) in materials synthesis near room temperature. The first strategy involves the synthesis of unprecedented trimethylsilyl chalcogenido metalates Cat+ [M(E-SiMe3 )n ]- (Cat=organic IL cation) of main group and transition metals (M=Ga, In, Sn, Zn, Cu, Ag, Au). These fully characterized homoleptic metalates serve as thermally metastable precursors in low-temperature syntheses of binary, ternary and even quaternary chalcogenide materials such as CIGS and CZTS relevant for semiconductor and photovoltaics (PV) applications. Furthermore, thermally and protolytically metastable coinage metalates Cat+ [M(ESiMe3 )2 ]- (M=Cu, Ag, Au; E=S, Se) are accessible. Finally, the use of precursors BMPyr[E-SiMe3 ] (E=Se,Te; BMPyr=1-butyl-1-methylpyrrolidinium) as sources of activated selenium and tellurium in the synthesis of high-grade thermoelectric nanoparticles Bi2 Se3 and Bi2 Te3 is shortly highlighted. The second synthesis strategy involves the metalation of ionic liquids Cat[S-H] and Cat[Se-H] by protolytically highly active metal alkyls or amides Rn M. This rather general approach towards unknown chalcogenido metalates Catm [Rn-1 M(E)]m (E=S, Se) will be demonstrated in a research paper following this short review head-to-tail.

A novel strategy to design a multilayer functionalized Cu2S thin film counter electrode with enhanced catalytic activity and stability for quantum dot sensitized solar cells

As the essential component of a quantum dot-sensitized solar cell (QDSC), the counter electrode (CE) plays an important role in electron transfer and catalytic reduction acquisition throughout the device. A novel route to design multilayer functionalized Cu₂S thin films as CEs with high catalytic activity and enhanced stability, as well as large specific surface area and high conductivity, is presented. Firstly, Mo-based films were prepared by magnetron sputtering on a glass substrate, and then porous CuZnMo conductive films were formed by etching with hydrochloric acid. Secondly, indium tin oxide (ITO) film was sputtered onto the porous structure to act as a protective layer, and a porous ITO/CuZnMo structured film was obtained after optimization. In the third step, multilayer Cu(x)/ITO/CuZnMo structured films were acquired by sputtering Cu films. Finally, multilayer Cu₂S(t)/ITO/CuZnMo functionalized film CEs were obtained via in situ sulfidation of sputtered Cu films. The functions of conduction and resistance to electrolyte corrosion were produced and enhanced by annealing an ITO layer at high temperature prior to Cu deposition, while catalytic activity enabled by Cu₂S was realized from Cu film sulfidation. The multilayer Cu₂S/ITO(500 °C)/CuZnMo functionalized films exhibit high catalytic activity and enhanced stability for resistance to electrolyte corrosion. Taking multilayer Cu₂S/ITO(500 °C)/CuZnMo films as CEs, the QDSCs demonstrated good stability of power conversion efficiency (PCE) after 500 h of irradiation, from an initial 4.21% to a final 4.00%. Furthermore, the thickness of Cu₂S film modulated by the duration of Cu sputtering was investigated. It was found that the QDSCs using multilayer Cu₂S(40 min)/ITO/CuZnMo functionalized film with a Cu₂S thickness of 1.2 μm as CE exhibit the best performance, and the R _ct value was 0.57 Ω. The best photovoltaic performance with a PCE of 5.21% (V _oc = 533.1 mV, J _sc = 18.80 mA cm^-2, FF = 52.84%) was achieved under AM 1.5 radiation with an incident power of 100 mW cm^-2. This design of a multilayer functionalized CE introduces potential alternatives to the common brass-based CE for long-term QDSCs with high performance.

Gas-phase electronic properties of tri-cationic imidazolium-based ionic liquids in comparison with mono- and di-cationic ionic liquids

The optimized geometries, electronic structures, and gas-phase properties of widely applicable non-linear trigeminal tri-cationic ILs (TT-X₃) were investigated using density functional theory (DFT) calculations and compared with mono- (M-X) and di-cationic (D-X₂) ionic liquids. The studied ILs are based on the imidazolium cation containing halide (X^‾) anions, where X^‾ = Cl^‾, Br^‾ and I^‾. Inter-molecular hydrogen bonds were studied by atoms in molecules (AIM) and natural bond orbital (NBO) analyses. Accordingly the most significant cation-anion charge transfer is related to C₁-H₁ … X (X = Cl, Br, I) interaction which strongly occurs in TT-X₃ ILs and especially in TT-Cl₃. Among ILs under investigation, TT-Cl₃ has the strongest cation-anion interaction. Also M - I IL has the largest and D-Cl₂ has the smallest electrical dipole moment.

Free-Standing Ion-Conductive Gels Based on Polymerizable Imidazolium Ionic Liquids

A free-standing ion-conductive gel is formed by spontaneous self-assembly of the amphiphilic ionic liquid 1-tetradecyl-3-methylimidazolium chloride (C₁₄MIm·Cl) and the cross-linkable monomer 6-hexanediol diacrylate (HDODA) in a mixed solvent of 1-octene, 1-butanol, and water. The ionic conductivity of this ion gel is 24 mS cm^-1 at 33 °C. To enhance the mechanical strength of the ion gels, the acrylate ionic liquid 1-(2-acryloyloxyundecyl)-3-methylimidazolium bromide (A-C₁₁MIm·Br) was added, leading to significant morphological changes of the HDODA phase from spherical, ellipsoid, angular platelets to interconnected with increasing addition of the acrylate ionic liquid and consequent enhancement in the mechanical strength of the resulting ion gels. Small angle X-ray scattering data reveal that the ion gels are composed of bicontinuous phase. The formation of the anisotropic HDODA structures upon introduction of the acrylate ionic liquid was accompanied by a change of the bicontinuous phase to be undulated, which increased the ionic path through the formed film, resulting in reduced ionic conductivity. Such coaxial structured gels may be a promising route for developing highly ion-conductive as well as mechanically stable solid electrolyte systems.

Electrochemical Thermoelectric Conversion with Polysulfide as Redox Species

Thermocells convert waste heat to electricity without any pollution; however, the high cost and corrosivity of redox species hinder their commercialization. In this work, a thermocell that utilizes abundant polysulfide as redox species was demonstrated for the first time. 1-Butyl-1-methylpyrrolidinium polysulfide [(P₁₄ )₂ S₃ ] was synthesized, and the redox species were prepared by the addition of sulfur to the (P₁₄ )₂ S₃ solution in DMSO. In thermoelectric measurements, the Seebeck coefficient changed from -0.68 to +0.5 mV K^-1 through addition of sulfur to the cell. Operando UV/Vis spectroscopy and open-circuit voltage analysis revealed that this effect was attributed to the change in the dominating redox reactions by the addition of sulfur. This result also provides a thermodynamic view on polysulfides electrochemistry, which is of high importance for lithium-sulfur batteries.

Lithium Photo-intercalation of CdS-Sensitized WO3 Anode for Energy Storage and Photoelectrochromic Applications

Integration of solar-energy harvesting and storage functions has attracted significant research attention, as it holds promise for ultimate development of light-chargeable devices. In this context, a functional nanocomposite anode that not only permits electrochemical energy storage through Li-ion photo-intercalation, but also exhibits potential for photoelectrochromic applications, was investigated. The nanocomposite is made of the Li-ion intercalation compound WO₃ , thinly coated with TiO₂ and sensitized by the photoactive semiconductor CdS. During light exposure, the photoelectrons from CdS are transported to the WO₃ /electrolyte interface, where Li-ion intercalation takes place. Photoelectron transport is facilitated by the interfacial TiO₂ layer. The WO₃ was shown to be functional in multiple photocharge-discharge cycles, but the CdS suffers from degradation and photocorrosion. Hence, the selection of compatible semiconductors and protective coating strategies should be pursued to overcome these issues.

Interface Engineering in Quantum-Dot-Sensitized Solar Cells

The unique properties of II-VI semiconductor nanocrystals such as superior light absorption, size-dependent optoelectronic properties, solution processability, and interesting photophysics prompted quantum-dot-sensitized solar cells (QDSSCs) as promising candidates for next-generation photovoltaic (PV) technology. QDSSCs have advantages such as low-cost device fabrication, multiple exciton generation, and the possibility to push over the theoretical power conversion efficiency (PCE) limit of 32%. In spite of dedicated research efforts to enhance the PCE, optimize individual solar cell components, and better understand the underlying science, QDSSCs have unfortunately not lived up to their potential due to shortcomings in the fabrication process and with the QDs themselves. In this feature article, we briefly discuss the QDSSC concepts and mechanisms of the charge carrier recombination pathways that occur at multiple interfaces, viz., (i) metal oxide (MO)/QDs, (ii) MO/QDs/electrolyte, and (iii) counter electrode (CE)/electrolyte. The rational strategies that have been developed to minimize/block these charge recombination pathways are elaborated. The article concludes with a discussion of the present challenges in fabricating efficient devices and future prospects for QDSSCs.

Quantum dot-sensitized solar cells

A comprehensive overview of the development of quantum dot-sensitized solar cells (QDSCs) is presented.

Origin of the effects of PEG additives in electrolytes on the performance of quantum dot sensitized solar cells

It has been well established that polymer additives in electrolyte can impede the charge recombination processes at the photoanode/electrolyte interface, and improve performance, especially V_oc, of the resulting sensitized solar cells. However, there are few reports about the effect of electrolyte additives on counter electrode (CE) performance. Herein, we systematically investigated the effect of polyethylene glycol (PEG) additives with various molecular weights (M_w from 300 to 20 000) in polysulfide electrolyte on the performance of two representative CdSe and Zn–Cu–In–Se (ZCISe) quantum dot sensitized solar cells (QDSCs), and explored the mechanism of the observed effects. Electrochemical impedance spectroscopy measurements indicate that all PEG additives can improve the charge recombination resistance at the photoanode/electrolyte interface, therefore suppressing the unwanted charge recombination process, and enhancing the V_oc of the resulting cell devices accordingly. On the CE side, with the increase of M_w of PEG additives, the initial effect of reducing the charge transfer resistance at the CE/electrolyte interface evolves into an increasing resistance; accordingly the initial positive effect on FF turns into negative one. Accordingly, low M_w PEG can improve efficiency for both CdSe (increasing from 6.81% to 7.60%) and ZCISe QDSCs (increasing from 9.26% to 10.20%). High M_w PEG is still effective for CdSe QDSCs with an efficiency of 7.38%, but falls flat on ZCISe QDSCs (with an efficiency of 9.11%).

The origin for the effect of PEG additives in polysulfide electrolyte on the performance of both photoanode and counter electrode was explored, and a facile and general route for remarkably improving photovoltaic performance of QDSCs was offered.

New Antimony Selenide/Nickel Oxide Photocathode Boosts the Efficiency of Graphene Quantum-Dot Co-Sensitized Solar Cells

A novel assembly of a photocathode and a photoanode is investigated to explore their complementary effects in enhancing the photovoltaic performance of a quantum-dot solar cell (QDSC). While p-type nickel oxide (NiO) has been used previously, antimony selenide (Sb₂Se₃) has not been used in a QDSC, especially as a component of a counter electrode (CE) architecture that doubles as the photocathode. Here, near-infrared (NIR) light-absorbing Sb₂Se₃ nanoparticles (NPs) coated over electrodeposited NiO nanofibers on a carbon (C) fabric substrate was employed as the highly efficient photocathode. Quasi-spherical Sb₂Se₃ NPs, with a band gap of 1.13 eV, upon illumination, release photoexcited electrons in addition to other charge carriers at the CE to further enhance the reduction of the oxidized polysulfide. The p-type conducting behavior of Sb₂Se₃, coupled with a work function at 4.63 eV, also facilitates electron injection to polysulfide. The effect of graphene quantum dots (GQDs) as co-sensitizers as well as electron conduits is also investigated in which a TiO₂/CdS/GQDs photoanode structure in combination with a C-fabric CE delivered a power-conversion efficiency (PCE) of 5.28%, which is a vast improvement over the 4.23% that is obtained by using a TiO₂/CdS photoanode (without GQDs) with the same CE. GQDs, due to a superior conductance, impact efficiency more than Sb₂Se₃ NPs do. The best PCE of a TiO₂/CdS/GQDs-nS^2-/S_n^2--Sb₂Se₃/NiO/C-fabric cell is 5.96% (0.11 cm² area), which, when replicated on a smaller area of 0.06 cm², is seen to increase dramatically to 7.19%. The cell is also tested for 6 h of continuous irradiance. The rationalization for the channelized photogenerated electron movement, which augments the cell performance, is furnished in detail in these studies.

Solar cells with PbS quantum dot sensitized TiO2-multiwalled carbon nanotube composites, sulfide-titania gel and tin sulfide coated C-fabric

Novel approaches to boost quantum dot solar cell (QDSC) efficiencies are in demand. Herein, three strategies are used: (i) a hydrothermally synthesized TiO₂-multiwalled carbon nanotube (MWCNT) composite instead of conventional TiO₂, (ii) a counter electrode (CE) that has not been applied to QDSCs until now, namely, tin sulfide (SnS) nanoparticles (NPs) coated over a conductive carbon (C)-fabric, and (iii) a quasi-solid-state gel electrolyte composed of S^2-, an inert polymer and TiO₂ nanoparticles as opposed to a polysulfide solution based hole transport layer. MWCNTs by virtue of their high electrical conductivity and suitably positioned Fermi level (below the conduction bands of TiO₂ and PbS) allow fast photogenerated electron injection into the external circuit, and this is confirmed by a higher efficiency of 6.3% achieved for a TiO₂-MWCNT/PbS/ZnS based (champion) cell, compared to the corresponding TiO₂/PbS/ZnS based cell (4.45%). Nanoscale current map analysis of TiO₂ and TiO₂-MWCNTs reveals the presence of narrowly spaced highly conducting domains in the latter, which equips it with an average current carrying capability greater by a few orders of magnitude. Electron transport and recombination resistances are lower and higher respectively for the TiO₂-MWCNT/PbS/ZnS cell relative to the TiO₂/PbS/ZnS cell, thus leading to a high performance cell. The efficacy of SnS/C-fabric as a CE is confirmed from the higher efficiency achieved in cells with this CE compared to the C-fabric based cells. Lower charge transfer and diffusional resistances, slower photovoltage decay, high electrical conductance and lower redox potential impart high catalytic activity to the SnS/C-fabric assembly for sulfide reduction and thus endow the TiO₂-MWCNT/PbS/ZnS cell with a high open circuit voltage (0.9 V) and a large short circuit current density (∼20 mA cm^-2). This study attempts to unravel how simple strategies can amplify QDSC performances.

Modifying Titania Using the Molten-Salt-Assisted Self-Assembly Process for Cadmium Selenide-Quantum Dot-Sensitized Photoanodes

Sensitizing titania with semiconducting quantum dots (QDs) is an important field for the development of third-generation photovoltaics. Many methods have been developed to effectively incorporate QDs over the surface of mesoporous titania, assembled from the 20-25 nm titania nanoparticles. Here, we introduce a molten-salt-assisted self-assembly (MASA) method to fabricate CdSe-modified mesoporous titania photoanodes. A mixture of ethanol, two surfactants (cetyltrimethylammonium bromide and 10-lauryl ether), silica (tetramethyl orthosilicate) or titania source (Ti(OC₄H₉)₄, acid (HNO₃), and cadmium nitrate solution was infiltrated into the pores of mesoporous titania (assembled using Degussa 25, P25) and immediately calcined at 450 °C to obtain mesoporous cadmium oxide-silica-titania (meso-CdO-SiO₂-P25) or cadmium titanate-titania (meso-CdTiO₃-P25) films. The MASA process is a simple method to smoothly coat or fill the pores of titania with mesoporous CdO-SiO₂ or CdTiO₃ that can be reacted under an H₂Se atmosphere to convert cadmium species to CdSe at 100 °C. Etching of the silica films with a very dilute hydrogen fluoride solution produces mesoporous CdSe-titania (meso-CdSe-P25) electrodes. The method is flexible to adjust the CdSe/TiO₂ mole ratio over a very broad range in the films. The films were characterized at every stage of the preparation to demonstrate the effectiveness of the method. The electrodes were also tested in a simple two-electrode solar cell to demonstrate the performance of the electrodes that have a power conversion efficiency of 3.35%.

Molecular Dynamics Simulations of Amide Functionalized Imidazolium Bis(trifluoromethanesulfonyl)imide Dicationic Ionic Liquids

In the present study, the structure and dynamics of three dicationic ionic liquids (DILs) with a functional amide group in the imidazolium ring with bis(trifluoromethanesulfonyl)imide, [TFSI]^- anion has been studied by molecular dynamics (MD) simulations. Densities, radial distribution functions (RDFs), combined distribution functions (CDFs), spatial distribution functions, mean-square displacements (MSD), and self-diffusivities for the ions have been calculated from the MD simulations. The calculated densities for [C₄(amim)₂][TFSI]₂ at different temperatures agreed well with the experimental values. The calculated RDFs and CDFs show that the anions are well organized around the amide group and imidazolium rings and the favorite sites of interaction of the [TFSI]^- ion are the hydrogen atoms of the amide group and hydrogen atoms of the imidazolium ring of the cation. The calculated MSDs indicated that the diffusion coefficients of the studied DILs are 1 order of magnitude smaller than those of DILs with a comparable molar mass.

Study on dynamic properties of the photoexcited charge carriers at anatase TiO2 nanowires/fluorine doped tin oxide interface

The photoexcited electrons transfer dynamics at the TiO₂ film/fluorine doped tin oxide (FTO) interface of anatase TiO₂ nanowire arrays (NWAs) and QD-sensitized TiO₂ NWAs films have been studied by using surface photovoltage (SPV) and transient photovoltage (TPV) techniques. Various SPV and TPV responses were obtained when the laser beam was incident from the front side illumination and back side illumination. Based on the work function values of anatase TiO₂ NWAs and FTO, the results indicate that diffusion is the major way for the separation and transfer of the photoexcited charge in the both anatase TiO₂ NWAs and QD-sensitized TiO₂ NWAs films under front side illumination. And the photoexcited charge were separated by drift under the built-in electric field at the TiO₂ film/FTO interface for anatase TiO₂ NWAs and QD-sensitized TiO₂ NWAs films under back side illumination. In addition, under back side illumination the built-in electric field and band structure of CdS/CdSe QDs and anatase TiO₂ NWAs lead to the separation and transfer of the photoexcited charge for CdS/CdSe QDs sensitized TiO₂ NWAs/FTO film. As the intensity of illumination increases, the effect of built-in electric field on the separation and transfer of the photoexcited charge in the QD-sensitized TiO₂ NWAs film decreases.

Structural properties of geminal dicationic ionic liquid/water mixtures: a theoretical and experimental insight

The structural properties of geminal dicationic ionic liquid/water mixtures have been investigated using EXAFS spectroscopy and molecular dynamics simulations.

Integration of CdSe/CdSexTe1-x Type-II Heterojunction Nanorods into Hierarchically Porous TiO2 Electrode for Efficient Solar Energy Conversion

Semiconductor sensitized solar cells, a promising candidate for next-generation photovoltaics, have seen notable progress using 0-D quantum dots as light harvesting materials. Integration of higher-dimensional nanostructures and their multi-composition variants into sensitized solar cells is, however, still not fully investigated despite their unique features potentially beneficial for improving performance. Herein, CdSe/CdSe_xTe_1−x type-II heterojunction nanorods are utilized as novel light harvesters for sensitized solar cells for the first time. The CdSe/CdSe_xTe_1−x heterojunction-nanorod sensitized solar cell exhibits ~33% improvement in the power conversion efficiency compared to its single-component counterpart, resulting from superior optoelectronic properties of the type-II heterostructure and 1-octanethiol ligands aiding facile electron extraction at the heterojunction nanorod-TiO₂ interface. Additional ~32% enhancement in power conversion efficiency is achieved by introducing percolation channels of large pores in the mesoporous TiO₂ electrode, which allow 1-D sensitizers to infiltrate the entire depth of electrode. These strategies combined together lead to 3.02% power conversion efficiency, which is one of the highest values among sensitized solar cells utilizing 1-D nanostructures as sensitizer materials.

Stable, High-Efficiency Pyrrolidinium-Based Electrolyte for Solid-State Dye-Sensitized Solar Cells

We synthesized a series of pyrrolidinium based dicationic ionic crystals with high melting point and good thermal stability. Research on the crystal structure shows that there are ordered three-dimensional ionic channels in these crystals which is favorable for the ionic conductor to achieve high conductivity and diffusion coefficient. These ionic crystals are applied to electrolyte as matrix in dye sensitized solar cells, and the influence of crystal structure (including the alkylene chain separating two pyrrolidinium rings and anion) versus the device performances are studied by steady-state voltammography, current-voltage trace, and electrochemical impedance spectroscopy. As the solid state electrolyte, an optimized efficiency of 6.02% have achieved under full sunlight irradiation using ionic crystal [C6BEP][TFSI]2. And the device based on this solid electrolyte shows the excellent long-term stability, maintaining 92% of the initial efficiency after 960 h. This study elucidates fundamental the structure of dicationic crystal and provide useful clues for further improvement of solid-state electrolytes in DSSC.

Capping Ligand-Induced Self-Assembly for Quantum Dot Sensitized Solar Cells

Quantum dot-sensitized solar cells (QDSCs), having the advantages of low-cost assembling process, economically viable materials and intrinsic optoelectronic properties of QD sensitizers, are regarded as attractive candidates for the third-generation solar cells. In spite of the previous unsatisfied performance resulted from poor sensitization, an increasing power conversion efficiency has been experimentally confirmed with the development of effective deposition approaches in the last five years. In this Perspective article, we present an overview on versatile QD deposition methods, regarding mainly the effective loading of QDs and surface chemistry issues. Linker-assisted assembly, a most efficient sensitizer deposition approach to achieve fast, uniform and dense coverage of the sensitizers on mesoporous TiO2 film electrode, will be discussed with emphasis. Recent advances based on this deposition technique in achieving high efficiency are presented. Also, combined efforts regarding the overall improvement of the device have been discussed to provide more possible access to higher power conversion efficiencies of the QDSCs.

Structure study of a microemulsion system with an ionic liquid

A ternary mixture with an IL, C₁₄MIM·Cl, exhibits a great conformational change from single crystal to microemulsion using water.

Amino- and ionic liquid-functionalised nanocrystalline ZnO via silane anchoring – an antimicrobial synergy

The synthesis of highly antimicrobial nanocrystalline zinc oxide and its covalent modifications are presented.

Access to pure and highly volatile hydrochalcogenide ionic liquids

The reaction of H₂S with methylcarbonate salts allows access to pure hydrosulphide ILs, which show an astoundingly high volatility below 100 °C allowing high-end purification and ionic single crystal growth by sublimation.

Photovoltaic properties of multilayered quantum dot/quantum rod-sensitized TiO2 solar cells fabricated by SILAR and electrophoresis

A multilayered semiconductor sensitizer structure composed of three differently sized CdSe quantum rods and CdS quantum dots.