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We report an efficiency enhancement of solution-processed CuIn(S,Se)2 (CISSe) thin film solar cells via in situ incorporation of Al2O3. These films were produced using inks containing CuCl, InCl3, AlNO3 (Al/Al + In: 0.1) and thiourea dissolved in methanol. After spin coating of these solutions in air, samples were subjected to a selenization process. Auger electron spectroscopy depth-profiling analysis showed that Al is evenly distributed throughout the bulk of the film. Transmission electron microscopy revealed that AlNO3 precursor reacted with oxygen to form nanosized amorphous Al2O3 grains located within the bulk and grain boundaries of CISSe, as well as at both the top and bottom interfaces. Power conversion efficiency (PCE) as high as 11.6% (JSC: 35.8 mA cm−2, VOC: 518 mV, FF: 62.2%, no anti-reflection coating) was achieved with Al–CISSe solar cell devices integrated with CdS (chemical bath deposition, thickness: 80 nm) and ZnO/ITO bilayers (sputtered, thickness: 300 nm). The average PCE (10.1%, 〈JSC〉: 34.5 mA cm−2, 〈VOC〉: 491 mV, 〈FF〉: 59.8%) was nearly 4% (absolute) higher than that measured on CISSe baseline cells fabricated from solutions without Al (〈PCE〉 = 6.4%, 〈JSC〉: 32.8 mA cm−2, 〈VOC〉: 410 mV, 〈FF〉: 47.3%). This in situ Al2O3 incorporation is speculated to play a role in the enhancement of the VOC and FF of the devices through passivation of defects in CISSe reducing interface and bulk recombination, as evidenced by a reduced defect density and an increased activation energy of the dominant recombination mechanism from capacitance and temperature-dependent VOC measurements, respectively.

An industrial-scale time- and cost-effective route to produce a highly efficient and stable oxygen evolution reaction (OER) electrode is desirable and highly challenging. Here, we have developed a minute-scale Fenton-like reaction to produce a three-dimensional (3D) FeOOH/NiFe-LDH heterojunction OER electrode by using industrial Ni foam as an Ni source to react directly with a Fenton-like reagent. The resulting 3D electrode, comprising a xlow-crystalline nano-scale FeOOH/NiFe-LDH heterojunction with high electrolyte-permeability, afforded a remarkable OER performances with an overpotential of 238 mV at 100 mA cm−2, a Tafel slope of 28.9 mV dec−1, and stable running over 700 h. Our results suggested that the fully maximized three-dimensional FeOOH/NiFe-LDH heterojunction interactions would be the origination of the high OER activity, exhibiting big prospects for industrial-scale applications.

Urea electrolysis is an appealing energy conversion technology to produce hydrogen (H2) and alleviate the problem of urea-rich wastewater treatment concurrently. In particular, electrocatalytic performance can be dramatically enhanced by rationally modulating the surface charge distribution with a well-tuned heterostructure. Herein, a heterostructure is constructed by NiMoO4 nanosheets grown on an interior hollow NiS@Ni3S2 nanorods framework (NiS@Ni3S2/NiMoO4). Density functional theory (DFT) calculations demonstrate that the formed heterojunction structure leads to a tailored surface charge state of NiMoO4, with oxygen as the nucleophilic region and molybdenum as the electrophilic region, which facilitates the decomposition of urea molecules and thus significantly improves hydrogen evolution. As expected, the assembled NiS@Ni3S2/NiMoO4 system substantially expedites urea electrolysis activity with a cell voltage of 1.40 V at 10 mA cm−2, which is 200 mV less than the voltage of an overall water splitting system.

In this work, the porous SnS nanosheets with abundant ultra-small nanocrystals aligned on carbon microtubes are designed to achieve good structural stability, remarkable rate capability and high sodium storage capability.

Li-ion and K-ion batteries present their unique advantages of high energy density and low cost, respectively. It is a challenge to explore a universal anode with efficient electrochemical performance. Herein, a two-dimensional TiO2/reduced graphene oxide (RGO) composite was prepared by a facile hydrothermal method. TiO2 nanoparticles are transformed from Ti2C MXene and connect the RGO nanosheets to form a sheet-like structure. Serving as the anode material, the TiO2/RGO presents high capacity, remarkable rate ability and long cycling performance for both Li- and K-ion batteries. The superior electrochemical performance is attributed to the short ion diffusion path due to the small particle size (15–25 nm) and the highway for electron transport provided by RGO. In addition, RGO motivates the capacitive contribution, resulting in enhanced capacity and better rate performance. Meanwhile, the electrochemical kinetics of Li/K-ion storage was investigated by quantitative kinetics analysis. This work demonstrates a possibility to introduce the capacitive capacity to realize rapid ion storage and improve the cycling stability, providing a new strategy to design efficient electrodes for metal-ion batteries.

Urea electrolysis offers the prospect of cost-effective and energy-saving hydrogen production together with mitigating urea-rich wastewater pollution instead of overall water splitting. Hence, here, high-efficiency bifunctional electrocatalysts were developed for both the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) via the in situ vertical growth of thorny leaf-like (2D nanosheets supporting 1D nanowires) NiCoP on a carbon cloth (NiCoP/CC). After integrating the advantages of the synergistic effect between Ni and Co as well as the unique hierarchical structure combined with 1D nanowires, 2D nanosheets and a 3D conductive carbon cloth substrate, the electrode exhibited excellent electrocatalytic activity toward HER and UOR. The electrolytic cell assembled using NiCoP/CC as the anode and the cathode could provide current density of 10 mA cm−2 at a cell voltage of 1.42 V (160 mV less than that for its urea-free counterpart) as well as remarkable durability over 30 h. Thus, the cost-effectiveness and high activity of the NiCoP/CC electrode pave the way to explore transition metal-based electrocatalysts for urea electrolysis.

Designing and exploring earth-abundant but high-performance electrode materials are of crucial significance for the future large-scale development of supercapacitors. Herein, a facile anionic P-substitution strategy is used to in situ decorate ternary Ni–S–P nanoparticles on graphene nanosheets (G/Ni–S–P) for supercapacitors for the first time. Benefitting from the unique hierarchical structure and positive synergistic effects between each component, the resultant G/Ni–S–P composite delivers a spectacular specific capacity of 1406 C g−1 at 1 A g−1 with an outstanding rate capability of 60.2% at 120 A g−1, which is highly superior to those of the previously reported nickel based composites. The asymmetric supercapacitor assembled with the G/Ni–S–P and graphene/FeOOH composite as the cathode and anode exhibits high energy density up to 58.1 W h kg−1 and superb electrochemical stability with 4.9% decay after 30 000 continuous charge/discharge cycles. These intriguing electrochemical performances indicate that the G/Ni–S–P composite has enormous potential application in high-performance energy storage systems in the future.

The substantial overpotential of CO2 activation, the complex CO2 reduction pathway, and the competitive H2 evolution reaction (HER) limit the practical applications of CO2-based electrochemical energy conversion and storage technologies due to their low energy efficiency and product selectivity. Here, we proposed a strategy that combines mesopores and redox-active couple to effectively capture CO2 and selectively generate CO product. As an example, we construct a redox-active couple, Zn2+/Zn+, on the low-crystallinity mesoporous ZnGa2O4 electrocatalyst. The mesopores not only help to capture CO2 effectively but also inhibit the H2 evolution. The weak lattice constraint of low crystallinity benefits the formation of a Zn2+/Zn+ redox couple to strongly interact with CO2 molecule for subsequent activation and catalytic conversion, thus effectively decreasing the activation energy of CO2 to the active species CO2− and accelerating the proton transfer to form the crucial COOH* intermediate. Consequently, this catalyst exhibited a high faradaic efficiency of 96% among Zn-based electrodes for CO generation at the relatively low applied potential of −1.4 V vs. Ag/AgCl (−0.8 V vs. RHE), and excellent stability during 10 h operation in a 0.1 M KHCO3 solution.

Developing cost-efficient and effective catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a great challenge for application in high-efficiency water electrolyzers. In this work, we design a highly efficient and durable water splitting system in an alkaline solution, in which platinum (Pt) sub-nanocluster (average size: 0.59 nm) functionalized nickel–iron layered double hydroxide nanosheets on carbon fiber cloth (Pt–NiFe LDH/CC) serve as the cathode and hierarchical (Ni0.77Fe0.23)Se2 nanosheets on CC ((Ni0.77Fe0.23)Se2/CC) act as the anode. For the HER, the three-dimensional (3D) Pt–NiFe LDH/CC electrode with an ultralow Pt content (1.56 wt%) drives a current density of 10 mA cm−2 at an ultralow overpotential of 28 mV. For the OER, the edge-rich (Ni0.77Fe0.23)Se2/CC electrode displays a current density of 10 mA cm−2 at a small overpotential of 228 mV, and the Tafel slope is as low as 69 mV dec−1. More importantly, the assembled Pt–NiFe LDH/CC||(Ni0.77Fe0.23)Se2/CC water splitting electrolyzer exhibits a high current density of 30 mA cm−2 at a low cell voltage of 1.57 V, which is superior to that of the electrolyzer assembled using commercial 20 wt% Pt/C and RuO2 electrodes (30 mA cm−2 at 1.62 V). Additionally, the Pt–NiFe LDH/CC||(Ni0.77Fe0.23)Se2/CC electrolyzer displays excellent stability over 40 h even at a high current density of 50 mA cm−2, which shows its great potential in the practical applications of full water splitting.

In this paper, K-doped δ-MnO2 nanoflowers decorated with Au nanoparticles (MnO2–Au) were synthesized by a hydrothermal method. To probe the effect of the band gaps in the MnO2 support over the surface plasmon resonance (SPR)-mediated catalytic conversions on Au nanoparticles (NPs), the oxidation of p-aminothiophenol (PATP) to p,p′-dimercaptoazobenzene (DMAB) was used as a model reaction. We found that the PATP conversion was significantly higher for the MnO2–Au hybrid compared with its individual Au NPs under excitation at 633 nm. Furthermore, the activities of the MnO2–Au materials increased as the MnO2 support displayed higher K-doped levels, which led to narrower band gaps. These results could be explained based on the transfer of photogenerated electrons from MnO2 to Au, increasing the electron density in Au NPs and thus contributing to improved SPR-mediated activity. In this case, our observations show that tuning the band gaps can have a significant impact on SPR-mediated conversions, in which narrower band gaps should facilitate the charge transfer of SPR-excited charge carriers and thus lead to better performances. Our findings presented may provide important insights into the role of the support materials in plasmonic catalysis, indicating that, in addition to the control over several physical and chemical parameters (such as shape, surface area, defects, among others), the proper tuning of the band gap can serve as an effective strategy for the optimization of activities.

To balance the electrochemical performance gap between the Li+ insertion/deintercalation anode and the anion adsorption/desorption cathode, in this paper, for the first time, we investigated MnNb2O6 as a new rate capability type anode material for lithium-ion capacitors (LICs). Novel calendula-like MnNb2O6 particles anchored on reduced graphene oxide (rGO) were prepared via a simple two-step hydrothermal route. The special three-dimensional structure and cross-linked conductive network constructed by graphene could shorten the lithium-ion diffusion path, efficiently facilitate electron transmission and adapt to volume strain without shedding during the long-term charge/discharge process. This resulted in excellent charge storage capacity and reasonably superior cycling stability. MnNb2O6@rGO//AC LICs assembled with MnNb2O6@rGO as the cathode and activated carbon (AC) as the anode exhibited excellent performance with maximum energy density of 118 W h kg−1 and power density of 8000 W kg−1 based on the total mass loading of the active material weight. The initial capacity retention was up to 88% after 10 000 charge/discharge cycles, which was higher than that of bimetallic oxide materials reported so far. Therefore, this study might provide a novel rate capability anode material for LICs with high performance.

A novel ultrafiltration membrane is developed by incorporating in situ self-assembled polymeric nanoparticles into the membrane matrix. The chemical stability of the nanoparticles in regard to pH and temperature is explored via a rational method. The result indicates that the electrostatic interaction strength between the two polyelectrolytes can withstand a broad pH range (pH 1–11) and a relatively high temperature (80 °C). Meanwhile, the nanoparticle size and distribution in the membranes are investigated by scanning electron microscopy (SEM), which are proved to be affected by the polyelectrolyte concentration and molecular weight. The contact angle values of the prepared membranes show that the membrane hydrophilicity is improved by adding polymeric nanoparticles. Furthermore, the molecular weight cut-off and pore size of the membranes are increased with added nanoparticle loading. More importantly, the mixed matrix membranes exhibit simultaneous increases in permeability and rejection of contaminants compared with the pristine PES membrane, which is ascribed to the appropriate pore size and enhanced hydrophilicity of the membranes. Especially, the composite membrane mixed with 3 wt% polymeric nanoparticles displays the highest pure water flux (460 L m−2 h−1), which is 3 times that of the pristine PES membrane, and 97.6% rejection of BSA. This work provides a new strategy for preparing flexible polymeric nanoparticles and developing high-performance mixed matrix membranes for water treatment.

For n–i–p type perovskite solar cells (Pero-SCs), one of the limitations which hinder the improvement of device performance is the extremely low electrical conductivity of the TiO2 electron transport layer (ETL). Herein, two novel functionalized water-soluble fullerene derivatives C60O∼18(OH)∼10(NH2)∼8 (f-C60) and C70O∼18(OH)∼10(NH2)∼10 (f-C70) were prepared and utilized as buffer layers between ITO and a vacuum-deposited fullerene C60 ETL in Pero-SCs. After inserting f-C60 and f-C70 layers, the Pero-SCs showed an enhanced crystallinity of the perovskite film, more efficient charge transport, reduced recombination and a decreased charge-transport resistance. Therefore, a summit power conversion efficiency (PCE) of 16.97% was achieved for the device with the f-C60/C60 ETL, which was ∼24% higher than that of the control device (13.71%). The PCE of the Pero-SC based on the f-C70/C60 ETL also exhibited a 16% enhancement. This work demonstrated the great potential of f-C60 and f-C70 for application as ETLs in Pero-SCs.

One-dimensional (1D) nanostructures have been identified as the most viable structures for high-performance supercapacitors from the view of high ion-accessible surface area and rapid electron transport path as well as excellent mechanical properties. Herein, we report a “stripping and cutting” strategy to produce 1D carbon nanobelts (CNB) from tofu with irregular structures through a molten salts assisted technique. It is a completely novel and green avenue for constructing 1D carbon materials from biomass, showing large commercial potential. The resultant CNB electrode delivers a high specific capacitance (262 F g−1 at 0.5 A g−1) and outstanding cycling stability with capacitance retention up to 102% after 10 000 continuous charging/discharging cycles. Additionally, a CNB//CNB symmetric supercapacitor and CNB//MnO2–CNB asymmetric supercapacitor are assembled and reach energy densities of 18.19 and 29.24 W h kg−1, respectively. Therefore, such a simple, one-pot and low-cost process may have great potential for preparing eco-friendly biomass-derived carbon materials for high-performance supercapacitor electrodes.

In our work, we successfully design boron (B) and nitrogen (N) co-doped porous carbon tube bundle (B/N-PCTB) electrode materials which are directly derived from the biomass of dandelion fluff. The low-tortuosity, and open and porous structures contribute to electron transport along the tube wall and unimpeded ion diffusion inside the carbon tubes. The incorporation of heteroatoms into PCTBs can bring extra pseudocapacitance and double layer capacitance to enhance the overall capacitance. Benefiting from the hollow and open microstructure and heteroatom doping, the optimized B/N-PCTB electrode (active materials: 2.6 mg cm−2) possesses an impressive specific capacitance of 355 F g−1 at 1 A g−1. Even with an ultrahigh loading mass of 40 mg cm−2, the electrode still has a relatively high specific capacity of 216 F g−1 at 1 A g−1. The assembled symmetric cell with an active material loading of 80 mg cm−2 (cathode: 40 mg cm−2; anode: 40 mg cm−2) shows a superior volumetric energy density of 12.15 W h L−1 at the power density of 699.84 W L−1. The facile yet high-performance porous carbon tube bundle is a promising material which can be applied in many other fields such as lithium ion batteries, hydrogen evolution reaction, and heavy metal ion adsorption.

Both tin oxide (SnO2) and fullerenes have been reported as electron selective layers (ESLs) for producing efficient lead halide perovskite solar cells. Here, we report that SnO2 and fullerenes can work cooperatively to further boost the performance of perovskite solar cells. We find that fullerenes can be redissolved during perovskite deposition, allowing ultra-thin fullerenes to be retained at the interface and some dissolved fullerenes infiltrate into perovskite grain boundaries. The SnO2 layer blocks holes effectively; whereas, the fullerenes promote electron transfer and passivate both the SnO2/perovskite interface and perovskite grain boundaries. With careful device optimization, the best-performing planar perovskite solar cell using a fullerene passivated SnO2 ESL has achieved a steady-state efficiency of 17.75% and a power conversion efficiency of 19.12% with an open circuit voltage of 1.12 V, a short-circuit current density of 22.61 mA cm−2, and a fill factor of 75.8% when measured under reverse voltage scanning. We find that the partial dissolving of fullerenes during perovskite deposition is the key for fabricating high-performance perovskite solar cells based on metal oxide/fullerene ESLs.

Lithium–sulphur batteries have attracted increasing interest due to their high theoretical specific capacity, advantageous economy, and environmental friendliness. With migration of soluble lithium polysulfide (Li2Sn, 4 < n ≤ 8) in mind, we prepared one novel Zn(II) metal–organic framework (MOF) based separator for lithium–sulphur batteries. It is able to play an efficient role as an ionic sieve for the soluble polysulfide ions. More importantly, the battery with Zn(II)–MOF based separator exhibited much lower capacity decay of 0.041% per cycle at 1C over 1000 cycles.

A novel strategy was used to prepare a high performance micro-porous polymer electrolyte (MPE) from a poly(arylene ether ketone) (PAEK)/poly(ethylene glycol) grafted poly(arylene ether ketone) (PAEK-g-PEG) polymer composite membrane matrix incorporating a chitosan based LiClO4 gel electrolyte. The morphology, porosity, and thermal and mechanical properties of the PAEK/PAEK-g-PEG polymer blend membrane matrix were investigated. To improve the liquid retention capacity of the MPE, a simple but effective method involving the addition of chitosan was implemented. The effects of chitosan concentration on the liquid uptake and leakage behaviors as well as the ionic conductivity of the electrolyte were also evaluated. The synthesized MPE exhibited an ionic conductivity as high as 8 × 10−3 S cm−1 at room temperature. More importantly, a novel solid-state electric double layer capacitor (S-EDLC) could be fabricated using the synthesized MPE and activated carbon electrodes. For comparison, an EDLC was also assembled using the corresponding aqueous electrolyte and a commercial separator (NKK-MPF30AC-100). Alternating current (AC) impedance measurement results showed that the interfacial compatibility of the MPE and the activated carbon electrodes was high. Meanwhile, the as-prepared S-EDLC showed a specific capacitance of 118.63 F g−1, with an energy density of 7.87 W h kg−1 and power density being 95.97 W kg−1 at a current density of 1 A g−1. Furthermore, the S-EDLC exhibited greater cell-cycling stability after 5000 charge/discharge cycles than did the EDLC, indicating that this novel MPE should be suitable for use in EDLCs and other energy storage systems.

We demonstrate a three-step sequential solution process to prepare PbI2-free CH3NH3PbI3 perovskite films. In this three-step method, a thermally unstable stoichiometric PbI2·CH3NH3Cl precursor film is first deposited on the mesoporous TiO2 substrate, followed by thermal decomposition to form PbI2, which is finally converted into CH3NH3PbI3 by dipping in a regular isopropanol solution of CH3NH3I at room temperature. In comparison to the two-step approach using similar processing conditions, the three-step method enables the formation of the PbI2 film through the thermal decomposition of the PbI2·CH3NH3Cl precursor film. This facilitates a rapid conversion of PbI2 to CH3NH3PbI3 without any traceable residue PbI2 in the final conversion step, leading to an improved device performance.

Ferroelectric solar cells based on ferroelectric oxides have attracted significant attention owing to many unique advantages, such as the switchable photocurrent and photovoltage, and the above bandgap open circuit voltages. However, the small photocurrent densities of the typical ferroelectric solar cells greatly limit their photovoltaic performance. In this report, we experimentally revealed the polarization switching properties of inorganic–organic hybrid perovskites and developed ferroelectric solar cells based on the hybrid perovskites. Hybrid perovskite methylammonium lead trihalide (MAPbX3) thin films exhibited 180° domain phase switching and polarization hysteresis loops. Ferroelectric solar cells based on the mixed halide MAPbI3−xClx thin film demonstrate a power conversion efficiency of 6.7% and the ferroelectric solar cells display switchable photovoltaic effects. This work provides an alternative but exhilarating solution for high-performance ferroelectric solar cells beyond inorganic ferroelectric oxides.

In a mesoporous hybrid perovskite solar cell (PSC), the mesoporous scaffold plays key roles in controlling the crystallization of the perovskite material and in the charge carrier transport, and hence is critical for developing highly efficient PSCs. Here we report a study on blending micrometer-long TiO2 nanorods (NRs) into the commonly used nanoparticles (NPs) to optimize the mesoporous structure, with the aim of enhancing the perovskite material loading and connectivity as well as light harvesting. It was found that with 5–10% of NR incorporation, a uniform scaffold can be spin-coated and the PSC performance was improved. In comparison to the pure NP-based device, the power conversion efficiency was increased by about 27% when 10% of the NRs were incorporated, due to enhanced light harvesting and charge collection. However, with more NR blending, a homogeneous scaffold cannot be formed, resulting in PSC performance degradation. These findings contribute to a better design of mesoporous scaffolds for high-performance PSCs.

Organometallic halide perovskites have emerged as a revolutionary class of light-absorbing semiconductors that have demonstrated a rapid increase in efficiency within a few years of active research. However, chemical stability is a major issue that hampers their large-scale implementation. Therefore being able to monitor the degradation rate of perovskite thin films may help understand the key factors governing the stability of this material system. Here, we use grazing incidence X-ray diffraction (GIXRD) measurements to elucidate the role of chlorine and the substrate in the stability of perovskite CH3NH3Pb(I1−xClx)3 (MAPbI) films for solar cells exposed to ambient atmosphere for more than 30 days. MAPbI films with different concentrations of chlorine were deposited on glass, ITO, and Si substrates. We found that the degradation rate of the perovskite that decomposes into PbI2 depends on the used substrate as well as the concentration of Cl. Through first principles calculations, we propose a mechanism on how chlorine affects the perovskite film properties. Furthermore, the power conversion efficiency of the fabricated perovskite planar heterojunction solar cells is investigated. The highest device performance with an efficiency of 15.7% is obtained with the 10% Cl film at the cost of stability. These findings lead to an improved understanding of more controllable processing schemes for hybrid perovskites. They also offer a potential route to control the degradation rate so as to create more favorable ways of producing stable films and devices from these materials.

CH3NH3PbI3 (MAPbI(3)) perovskite thin films that are solution-processed using either a one-step or two-step conventional method typically contain a significant number of defects (voids, pinholes) or PbI2 impurities, which have a detrimental effect on the performance of planar perovskite solar cells (PSCs) fabricated using those films. To overcome this issue, we show that enhancement of the solid-state reaction between inorganic-organic precursors is an effective route for the growth of compact, phase-pure MAPbI(3) perovskite thin films with no voids or pinholes. To ensure uniform solid-state conversion (MAI + PbI2 -> MAPbI(3)) across the entire film thickness, a new successive spin coating/annealing (SSCA) process is used, where MAI is repeatedly infiltrated into a nanoporous PbI2 film, followed by thermal annealing. The mechanisms involved in the SSCA process are elucidated by monitoring the evolution of the phases during the reaction. Owing to these desirable characteristics (high-purity, full-coverage, enhanced smoothness and compactness) of the SSCA MAPbI(3) films, planar PSCs based on these perovskite thin films delivered a maximum power conversion efficiency (PCE) close to 15%. Furthermore, PSCs fabricated using partially converted nanoporous PbI2 thin films delivered a surprising PCE approaching 10%, suggesting continuous MAPbI(3) phase formation throughout the entire film at each spin coating/annealing process. The advantages gained from enhancing the solid-state precursor reactions allow better control of the growth of the perovskite making the SSCA process more robust.

The room-temperature solvent–solvent extraction (SSE) concept is used for the deposition of hybrid-perovskite thin films over large areas. In this simple process, perovskite precursor solution is spin-coated onto a substrate, and instead of the conventional thermal annealing treatment, the coated substrate is immediately immersed in a bath of another solvent at room temperature. This results in efficient extraction of the precursor-solvent and induces rapid crystallization of uniform, ultra-smooth perovskite thin films. The mechanisms involved in the SSE process are studied further, and its versatility in depositing high quality thin films of controlled thicknesses (20 to 700 nm) and various compositions (CH3NH3PbI(3−x)Brx; x = 0, 1, 2, or 3) is demonstrated. Planar perovskite solar cells (PSCs) based on SSE-deposited CH3NH3PbI3 perovskite thin films deliver power conversion efficiency (PCE) up to 15.2%, and most notably an average PCE of 10.1% for PSCs with sub-100 nm semi-transparent perovskite thin films. The SSE method has generic appeal, and its key attributes—room-temperature process, rapid crystallization, large-area uniform deposition, film-thickness control, ultra-smoothness, and compositional versatility—make the SSE method potentially suitable for roll-to-roll scalable processing of hybrid-perovskite thin films for future multifunctional PSCs.

A new layered Na0.3MoO2 exhibits a reversible capacity of 146 mA h g−1, remarkable cycling stability and good rate capability for sodium half-cells. And a Na0.3MoO2//Na0.8Ni0.4Ti0.6O2 full intercalation-type sodium-ion cell is fabricated and it displays an excellent cycling stability. These results indicate that molybdenum-based oxide is a promising anode material for sodium-ion batteries.

Correction for ‘Ultrasmall-sized SnS nanosheets vertically aligned on carbon microtubes for sodium-ion capacitors with high energy density’ by Jing Zhao et al., J. Mater. Chem. A, 2019, 7, 4047–4054.

Three 9,9-dihexyl-9H-fluorene (DHF) functionalized zinc porphyrin dyes (coded as ZZX-N3, ZZX-N4, and ZZX-N5) were designed and synthesized for dye-sensitized solar cells. Then, DHF and benzoic acid were conjugated to the porphyrin ring through triple bonds to act as a spacer to elongate the π-conjugation and as an acceptor for an efficient electron injection, respectively. A bis(9,9-dihexyl-9H-fluorene-7-yl)amine (BFA) and a bis(4-hexylphenyl)amine (BPA) were further linked to DHF to act as electron donors in ZZX-N3 and ZZX-N4, respectively. ZZX-N5 did not have any electron donor and served as a reference. Moreover, ZZX-N3- and ZZX-N4-sensitized cells exhibited broader sunlight absorption than ZZX-N5, and as a result, higher photon-to-electricity efficiency (PCE) (ZZX-N3, 3.83%; ZZX-N4, 4.2%; ZZX-N5, 3.70%) was observed. The results are consistent with well-separated HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) in ZZX-N3 and ZZX-N4 than in ZZX-N5. However, the overall conversion efficiency of ZZX-N3- and ZZX-N4-sensitized cells was low, which is due to significant dye aggregation induced by the extra long alkyl-chains on the donor groups. This was evidenced by blue and red shifts of the absorption spectra of dye-coated TiO2 films. In addition, the extra long-chains also did not offer better shielding to prevent electron recombination of injected electrons with I3− in electrolyte as revealed by electrochemical impedance spectroscopy. When a co-sensitizer (coded as PBS) was used, a new peak corresponding to the absorption of PBS at 560 nm was observed on the incident photon to charge carrier efficiency (IPCE) spectra; however, the overall photovoltaic performance was not improved due to the significant decrease of dye-loading density of porphyrin dyes, indicating a need to break off the trade-off between dye-loading and light-harvesting.

Li1.18Co0.15Ni0.15Mn0.52O2 cathode material was prepared by the sol–gel method. The material was coated with the ionic conductor Li3VO4via direct reaction with NH4VO3 at 350 °C. The Li3VO4 coated material had a higher ordered hexagonal layered structure, and less Li+/Ni2+ cation mixing. The surface of the coated material was composed of Li3VO4 polycrystals, which were impregnated into the bulk of the active material. The surface coating protected the material from contact with CO2 in the air, thus inhibiting the formation of an Li2CO3 layer. Electrochemical studies showed that the Li3VO4 surface coating improved the activation of Mn4+ ions, resulting in a high discharge capacity. It also prohibited the growth of a solid electrolyte interface film, and facilitated the charge transfer reactions at the electrode/electrolyte interface, thus improving the rate capability and cycle stability of the material. DSC analysis of the fully charged electrode showed that the temperature of the exothermic peak increased from 205.2 °C to 232.8 °C, and that the amount of heat that was released was reduced from 807.5 J g−1 to 551.0 J g−1, highlighting the improved thermal stability of the material after coating with Li3VO4 .