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CuFe(SxSe1−x)2 NPs with adjusted S/Se ratios were synthesized via a hot-injection method, which exhibited excellent electrocatalytic activities for water splitting due to the reduced band gap, regulated d-band center, and high exposure of active (220) facets.

Metal halide perovskites possess many physical properties amenable to optoelectronic applications, whereas the realization of these potentials has been hampered by their environmental and electronic instabilities. The morphological and molecular low dimensional perovskites and perovskite related materials have shown much promise in enhancing the chemical stability due to their unique molecular structures. Here we report on robust and reproducible four-terminal (4T) electrical measurements in a one-dimensional (1D) organic metal halide hybrid, (R)-{\alpha}-methylbenzylammonium lead triiodide ((R-{\alpha}-MBA)PbI3) made possible by its chemical stability. The results reveal a distinct intrinsic ion migration dynamic of single exponential, which underlies the unique 4T I-V characteristics. The dynamic is directly verified by real-time measurements of the transient ionic current. Our observations are consistent with photo-activation and field-assisted ion migration. The elucidated intrinsic ion dynamics may provide the physical basis for understanding and modelling the ubiquitous hysteresis in metal halides based electronic devices and new insights into the dynamics of ion migration in metal halide perovskites and hybrids in general.

The electrochemical reduction of nitrogen, as a sustainable alternative to the known Haber–Bosch process, possesses promising application prospects in the development of renewable energy storage systems. However, the yield of NH3 and Faraday efficiency are usually very low owing to the loss of active electrocatalysts and competitive hydrogen evolution reactions. Herein, uniform NiS@MoS2 core–shell microspheres are controllably prepared as a potential catalyst for an ambient electrocatalytic N2 reduction reaction. The NiS@MoS2 microspheres possess highly active intrinsic, sufficient accessible active sites, high structural porosity, and convenient transport channels, consequently boosting the transmission of electrons and mass. Additionally, the interfacial interaction between NiS and MoS2 facilitates electron transfer, which further improves the catalytic activity by optimizing the free energies of reaction intermediates. As a result, the titled NiS@MoS2 shows excellent electrochemical activity and selectivity, capable of achieving a relatively high NH3 yield of 9.66 μg h−1 mgcat−1 at −0.3 V (vs. the reversible hydrogen electrode, RHE) and a high FE of 14.8% at −0.1 V vs. RHE in 0.1 M Na2SO4. The work demonstrated here may open a new avenue for the rational design and synthesis of catalysts for the electrochemical synthesis of ammonia.

The photophysical tuning is reported for a series of tetraphenylphosphonium (TPP) metal halide hybrids containing distinct metal halides, TPP2 MXn (MXn =SbCl5 , MnCl4 , ZnCl4 , ZnCl2 Br2 , ZnBr4 ), from efficient phosphorescence to ultralong afterglow. The afterglow properties of TPP+ cations could be suspended for the hybrids containing low band gap emissive metal halide species, such as SbCl52- and MnCl42- , but significantly enhanced for the hybrids containing wide band gap non-emissive ZnCl42- . Structural and photophysical studies reveal that the enhanced afterglow is attributed to stronger π-π stacking and intermolecular electronic coupling between TPP+ cations in TPP2 ZnCl4 than in the pristine organic ionic compound TPPCl. Moreover, the afterglow in TPP2 ZnX4 can be tuned by controlling the halide composition, with the change from Cl to Br resulting in a shorter afterglow due to the heavy atom effect.

Scintillation based X-ray detection has received great attention for its application in a wide range of areas from security to healthcare. Here, we report highly efficient X-ray scintillators with state-of-the-art performance based on an organic metal halide, ethylenebis-triphenylphosphonium manganese (II) bromide ((C38H34P2)MnBr4), which can be prepared using a facile solution growth method at room temperature to form inch sized single crystals. This zero-dimensional organic metal halide hybrid exhibits green emission peaked at 517 nm with a photoluminescence quantum efficiency of ~ 95%. Its X-ray scintillation properties are characterized with an excellent linear response to X-ray dose rate, a high light yield of ~ 80,000 photon MeV−1, and a low detection limit of 72.8 nGy s−1. X-ray imaging tests show that scintillators based on (C38H34P2)MnBr4 powders provide an excellent visualization tool for X-ray radiography, and high resolution flexible scintillators can be fabricated by blending (C38H34P2)MnBr4 powders with polydimethylsiloxane., Scintillation-based X-ray detection is promising for applications in various areas ranging from security to healthcare, and low-cost and eco-friendly scintillation materials would be beneficial. Here the authors report a facile solution growth of organic manganese halide for efficient X-ray scintillation.

Metal-halide perovskites, in particular their nanocrystal forms, have emerged as a new generation of light-emitting materials with exceptional optical properties, including narrow emissions covering the whole visible region with high photoluminescence quantum efficiencies of up to near-unity. Remarkable progress has been achieved over the last few years in the areas of materials development and device integration. A variety of synthetic approaches have been established to precisely control the compositions and microstructures of metal-halide perovskite nanocrystals (NCs) with tunable bandgaps and emission colors. The use of metal-halide perovskite NCs as active materials for optoelectronic devices has been extensively explored. Here, we provide a brief overview of recent advances in the development and application of metal-halide perovskite NCs. From color tuning via ion exchange and manipulation of quantum size effects, to stability enhancement via surface passivation, new chemistry for materials development is discussed. In addition, processes in optoelectronic devices based on metal-halide perovskite NCs, in particular, light-emitting diodes and radiation detectors, will be introduced. Opportunities for future research in metal-halide perovskite NCs are provided as well.

Tin halide perovskites and perovskite-related materials have emerged as promising lead-free hybrid materials for various op-toelectronic applications. While remarkable progress has been achieved in...

Scintillators are utilized for X-ray detection in many important fields ranging from homeland security to health care. Developing low-cost, high-performance scintillation materials to address the i...

Bulk assemblies of zero-dimensional (0D) metal halides with exceptional structural versatility have enabled the development of a number of highly efficient emitters with tunable photophysical prope...

Surface passivation of metal halide perovskite thin films has proved to be critical for efficient and stable perovskite solar cells (PSCs), i.e. suppressing charge recombination at the interfaces between perovskite and charge transport layers for high device efficiency and preventing the penetration of degrading agents into the perovskite layer for high device stability. Here, we report the use of a new class of materials, phosphonium halide salts, i.e. triphenyl(9-ethyl-9H-carbazol-3-yl)-phosphonium bromide (TCPBr) and iodide (TCPI), as surface passivation agents for efficient and stable PSCs. Suppressed nonradiative recombination and enhanced interfacial hole extraction, enabled by this facile phosphonium halide passivation, resulted in PSCs with power conversion efficiencies (PCEs) of >20.1% (∼18.5% for pristine MAPbI3 devices). Phosphonium halide passivation also reduced the hysteresis index from 11.2% (pristine device) to 5.4% (TCPBr passivated device). Moreover, the hydrophobic phosphonium halide passivation layers significantly suppressed moisture penetration and ion migration, greatly enhancing the device stability. It was found that unencapsulated solar cells based on TCPBr treated MAPbI3 thin layers retained more than 90% of the initial PCEs after more than 1000 hours storage under ambient conditions. Our work established the potential of phosphonium-based materials for surface passivation of metal halide perovskites, providing a new route towards efficient and stable perovskite optoelectronic devices.

Metal halide perovskite quantum dots (QDs) have excellent optoelectronic properties; however, their poor stability under water or thermal conditions remains an obstacle to commercialization. Here, we used a carboxyl functional group (−COOH) to enhance the ability of a covalent organic framework (COF) to adsorb lead ions and grow CH3NH3PbBr3 (MAPbBr3) QDs in situ into a mesoporous carboxyl-functionalized COF to construct MAPbBr3 QDs@COF core–shell-like composites to improve the stability of perovskites. Owing to the protection of the COF, the as-prepared composites exhibited enhanced water stability, and the characteristic fluorescence was maintained for more than 15 d. These MAPbBr3 QDs@COF composites can be used to fabricate white light-emitting diodes with a color comparable to natural white emission. This work demonstrates the importance of functional groups for the in situ growth of perovskite QDs, and coating with a porous structure is an effective way to improve the stability of metal halide perovskites.

Zero-dimensional (0D) organic metal halide hybrids are an emerging class of light emitting materials with exceptional photoluminescence quantum efficiencies (PLQEs), thanks to their perfect “host–g...

Organometal halide perovskite materials, in particular colloidal perovskite nanocrystals (NCs), have been investigated extensively as next-generation light-emitting materials. However, producing highly efficient and stable perovskite thin films from colloidal NCs is not trivial, as dissociation of surfactants often occurs during the thin-film formation. Here, we demonstrate a facile solution-processing approach to prepare perovskite nanocomposite thin films by using phosphonium as the capping ligand for methylammonium lead bromide (MAPbBr

Carbon-based CsPbBr3 perovskite solar cell is an emerging inorganic perovskite solar cell with the advantages of simple fabrication process and excellent stability. However, power conversion efficiency of carbon-based CsPbBr3 perovskite solar cells is still unsatisfactory up to now, as the direct contact of the CsPbBr3 with carbon is plagued with interfacial recombination sites and undesirable hole extraction barrier. Here, we report an effective strategy that employs poly (3-hexylthiophene) (P3HT) to modify the CsPbBr3/carbon interface in carbon-based CsPbBr3 perovskite solar cells and enable higher efficiency. The systematic tests and analyses demonstrate that the P3HT interlayer can remarkably suppress the charge recombination and enhance the hole extraction capability via formation of favorable energy level alignment between CsPbBr3 film and carbon electrode, and passivation of the surface defect states of CsPbBr3 film. As a result, the carbon-based CsPbBr3 perovskite solar cell with P3HT interlayer achieves a high conversion efficiency of 6.49%, exhibiting an increase by 27% compared to pristine device. Moreover, the carbon-based CsPbBr3 perovskite solar cells with P3HT interlayer exhibits excellent stability in ambient air with almost no change in the power conversion efficiency of the unsealed device over 40 days.

Organic-inorganic metal halide hybrids are an important class of crystalline materials with exceptional structural and property tunability. Recently metal halide perovskites with ABX3 structure have been extensively investigated as new generation semiconductors for various optoelectronic devices, including photovoltaic cells, light emitting diodes, photodetectors, and lasers, for their exceptional optical and electronic properties. By controlling the morphological dimensionality, low dimensional metal halide perovskites, including 2D perovskite nanoplatelets, 1D perovskite nanowires, and 0D perovskite quantum dots, have been developed to exhibit distinct properties from their bulk counterparts, due to quantum size effects. Besides ABX3 perovskites, organic-inorganic metal halide hybrids, containing the same fundamental building block of metal halide octahedra (BX6), can also be assembled to possess other types of crystallographic structures. Using appropriate organic and inorganic components, low dimensional organic-inorganic metal halide hybrids with 2D, quasi-2D, corrugated-2D, 1D, and 0D structures at the molecular level have been developed and studied. Due to the strong quantum confinement and site isolation, these low dimensional metal halide hybrids at the molecular level exhibit remarkable and unique properties that are significantly different from those of ABX3 perovskites. In light of the rapid development of low dimensional metal halide perovskites and hybrids, it is indeed timely to review the recent progress in these areas. Also, there is a need to clarify the difference between morphological low dimensional metal halide perovskites and molecular level low dimensional metal halide hybrids, as currently the terminologies of low dimensional perovskites are not appropriately used in many cases. In this review article, we discuss the synthesis, characterization, application, and computational studies of low dimensional metal halide perovskites and hybrids.

Unstable solid electrolyte interphase (SEI) layer formation and uncontrolled lithium (Li) dendrites growth are two major obstacles that hinder the application of Li metal as the anode in Li batteries. To solve these problems, a multifunctional protective layer was designed for the first time using N2 plasma activation of the Li metal. A highly [001] oriented and flower shaped Li3N layer was obtained on the surface of Li metal with a plasma activation time less than 5 min. Due to high Young's modulus (48 GPa) and high ionic conductivity (5.02×10-1 mS cm-1), this unique protective layer can physically block the direct contact between reactive Li metal and the liquid organic electrolyte, and suppress the Li dendrites formation. It gives rise to a stable voltage profile with plating/stripping for 30,000 min in a symmetric cell. For Li/LCO full cell, the plasma activated Li3N electrode shows better capacity retention of more than 96% and higher capacity at a 5 C rate compared to bare Li anode. This plasma activation strategy provides a facile, scalable and efficient approach to realize a safe Li metal battery with superior electrochemical performance.

Lithium–sulfur batteries are currently attracting wide interest due to their high theoretical capacity, although their energy density is greatly limited by the low tap density of traditional C/S cathode materials. Herein hollow VO2@S microspheres were designed as cathode materials with high volumetric capacity by combining the intercalation and conversion mechanisms. The hollow microsphere can offer enough space for high sulfur loading, which results in a high tap density of 1.64 g cm−3, while VO2 can offer additional capacity by Li intercalation reactions and has strong interactions with polysulfides to prevent the shuttling effect by its in situ surface sulfidation. Therefore, the obtained materials delivered a high volumetric capacity (1084 mA h cm−3 at 0.1C) and good rate capability and cycling performance (440 mA h g−1 at 1.0C after 200 cycles). This study demonstrates that traditional cathode materials with a proper potential window would be an alternative host for sulfur to offer additional capacity and increase the energy density due to their high tap density.

Blockchain technology is widely used in finance, digital asset trading and other fields because of its characteristics of decentralization, unforgeability and sharing. Blockchain has become one of the hot topics in fintech research, which affects the development of traditional financial formats. It is considered as the cornerstone of digital economy. This paper systematically analyzes the characteristics of blockchain technology, the impact of blockchain technology on the operation and management of traditional commercial banks, and prospects the application of blockchain technology in commercial banks.

The fabrication of efficient and spectrally stable pure-blue perovskite light-emitting diodes (LEDs) has been elusive and remains of great interest. Herein, we incorporate diammonium salts into quasi-2D perovskite precursors for phase control of multiple quantum well structures to yield tunable and efficient emission in the blue region. With detailed characterizations and computational studies, we show that in situ passivation by the diammonium salts effectively modifies the surface energies of quasi-2D phases and inhibits the growth of low-band gap quasi-2D and 3D phases. Such phase control and in situ passivation could afford blue light-emitting perovskite thin films with high photoluminescence quantum efficiencies of, for instance, 75% for the emission peak at 471 nm. Using this perovskite thin film as an emitting layer, spectrally stable pure-blue LEDs with an emission peak at 474 nm and a full width at half-maximum of 26 nm could be fabricated to exhibit a brightness of 290 cd m-2 at 8 V and an external quantum efficiency of 2.17%.

Surface passivation of perovskite thin films has been established as a promising approach to improving both the efficiency and stability of perovskite solar cells (PSCs). While remarkable progress has been achieved with various surface passivating agents, long-term stability of PSCs has not been fully addressed. Here, we report a new strategy for surface passivation of PSCs using a low cost industrial organic pigment quinacridone (QA). The procedure involves solution processing a soluble derivative of QA, N,N-bis(tert-butyloxycarbonyl)-quinacridone (TBOC-QA), followed by facile thermal annealing to convert TBOC-QA to insoluble QA. With the halide perovskite thin films coated by QA, PSCs based on methylammonium lead Iodide (MAPbI3) showed significantly improved performance with remarkable stability. A PCE of 21.1% was achieved, which is much higher than 18.9% recorded for the unmodified devices. Density functional theory calculations revealed strong interactions between QA molecules and metal halides, which effectively reduced the surface defects of halide perovskite thin films and suppressed the nonradiative recombination. The QA coating with exceptional insolubility and hydrophobicity also led to remarkably enhanced contact angle from 35.6⁰ for the pristine MAPbI3 thin films to 77.2⁰ for QA coated MAPbI3 thin films. As a result, the stabilities of QA passivated MAPbI3 perovskite thin films and PSCs were greatly enhanced, retaining about 90 % of the initial efficiencies after more than 1000 hours storage under ambient conditions. The universality of this passivation strategy was evaluated by extending MAPbI3 systems to triple-cation mixed-halide perovskite systems, which further confirm the effectiveness of industrial pigment passivation of PSCs with enhanced efficiency and stability.

Metal ion-linked multilayers offer an easily prepared and modular architecture for controlling energy and electron transfer events on nanoparticle, metal oxide films. However, unlike with planar electrodes, the mesoporous nature of the films inherently limits both the thickness of the multilayer and subsequent diffusion through the pores. Here, we systematically investigated the role of TiO2 nanoparticle film porosity and metal ion-linked multilayer thickness in surface loading, through-pore diffusion, and overall device performance. The TiO2 porosity was controlled by varying TiO2 sintering times. Molecular multilayer thickness was controlled through assembling ZnII-linked bridging molecules (B = p-terphenyl diphosphonic acid) between the metal oxide and the Ru(bpy)2((4,4'-PO3H2)2bpy)]Cl2 dye (RuP), thus producing TiO2-(Bn)-RuP films. Using attenuated total reflectance infrared absorption and UV-vis spectroscopy, we observed that at least two molecular layers (i.e., TiO2-B2 or TiO2-B1-RuP) could be formed on all films but subsequent loading was dependent on the porosity of the TiO2. Rough estimates indicate that in a film with 34 nm average pore diameter, the maximum multilayer film thickness is on the order of 4.6-6 nm, which decreases with decreasing pore size. These films were then incorporated as the photoanodes in dye-sensitized solar cells with cobalt(II/III)tris(4,4'-di-tert-butyl-2,2'-bipyridine) as a redox mediator. In agreement with the surface-loading studies, electrochemical impedance spectroscopy measurements indicate that mediator diffusion is significantly hindered in films with thicker multilayers and less porous TiO2. Collectively, these results show that care must be taken to balance multilayer thickness, substrate porosity, and size of the mediator in designing and maximizing the performance of new multilayer energy and electron management architectures.

The design and synthesis of complex multi-component heterostructures is an effective strategy to fabricate cost-efficient catalysts for electrochemical water splitting. Herein, one-dimensional porous Fe3S4-Fe7Se8 heterostructured nanowires confined in carbon (Fe3S4-Fe7Se8@C) were synthesized via the selenization of Fe-based organic-inorganic nanowires. Benefiting from the merits of morphology, composition and surface structure characteristics, i.e., the high structural void porosity, the direct electrical pathways of nanowire topology and the conductive carbon layer coating, the titled catalyst not only offered a larger accessible electrocatalytic interface but also facilitated diffusion of the electrolyte and gas. Moreover, the electron redistribution at the Fe3S4-Fe7Se8 heterojunction interfaces reduced the adsorption free-energy barriers on the active sites, endowing the catalysts with faster reaction kinetics and improved electrocatalytic activity. Accordingly, the optimal Fe3S4-Fe7Se8@C produced a low hydrogen evolution reaction overpotential of 124 mV at 10 mA cm (-2) with a Tafel slope of 111.2 mV dec(-1), and an ultralow oxygen evolution reactions overpotential of 219 mV at 20 mA cm (-2 ), respectively. When applied as both anode and cathode for overall water splitting, a low battery voltage of 1.67 V was achieved along with excellent stability for at least 12 h. The work presented here offered a feasible scheme to fabricate non-noble metal-based electrocatalysts for water splitting. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. Funding Agencies|National Natural Science Foundation of ChinaNational Natural Science Foundation of China [21601120, 21771124, 21805181, 41877373]; China Postdoctoral Science FoundationChina Postdoctoral Science Foundation [2017M611529]; Science and Technology Commission of Shanghai MunicipalityScience & Technology Commission of Shanghai Municipality (STCSM) [17ZR1410500, 19ZR1418100]

All-inorganic CsPbIBr2 perovskite has been regarded as a promising candidate for perovskite solar cells (PSCs) considering its suitable bandgap and high stability. However, the poor quality of CsPbIBr2 film greatly impedes the performance improvement of CsPbIBr2-based PSCs. Herein, we report a facile strategy to improve the quality of CsPbIBr2 perovskite film by introducing cellulose acetate (CA) into the perovskite precursor solution. The interaction between the oxygen functional groups of CA and Pb2+ and the increase of the precursor viscosity induced by CA addition can slow down the crystallization rate of CsPbIBr2 perovskite, which allows the perovskite films have enough time to form high-quality crystal structure. By optimizing the amount of CA (the optimal amount of CA is 2.5 wt%), a high-quality CsPbIBr2 perovskite film with high crystallinity, large grain size, and smooth surface is obtained. As consequence, the carbon-based PSC with a structure of FTO/TiO2/perovskite/carbon using the CsPbIBr2 perovskite film with 2.5 wt% CA achieves a champion efficiency of 7.52%, which is increased by 40.8% compared with the cell based on pure CsPbIBr2 perovskite film. In addition, the PSC based on CsPbIBr2 film with CA exhibits an excellent long-term stability under both ambient condition and high-humidity environment.

Platinum (Pt)-based alloys are considerably promising electrocatalysts for the reduction of I–/I3– and Co2+/Co3+ redox couples in dye-sensitized solar cells (DSSCs). However, it is still challenging to minimize the dosage of Pt to achieve comparable or even higher catalytic efficiency. Here, by taking full advantages of the Mott–Schottky (M–S) effect at the metal–semiconductor interface, we successfully strategize a low-Pt-based M–S catalyst with enhanced electrocatalytic performance and stability for the large-scale application of DSSCs. The optimized M–S electrocatalyst of Ni3S4–Pt2X1 (X = Fe, Ni) heteronanorods is constructed by rationally controlling the ratio of Pt to transition metal in the hybrids. It was found that the electrons transferred from Ni3S4 to Pt2X1 at their interface under the Mott–Schottky effect result in the concentration of electrons onto Pt2X1 domains, which subsequently accelerates the regeneration of both I–/I3– and Co2+/Co3+ redox shuttles in DSSCs. As a result, the DSSC with N...

Metal-semiconductor based Mott-Schottky (M-S) heterojunctions combining two or more functionalities in one unit can effectively improve their catalytic activity and durability due to the electronic coupling effects between distinct components. Although tremendous progress has been made in structure fabrication, controllable synthesis of one-dimensional (1D) M-S heterojunction and its application as electrocatalysts is still lacking. Herein, uniform and well-defined 1D Ni3S4-PtCo heteronanorods are synthesized via a facile solution method and employed as counter electrode (CE) catalyst in the dye-sensitized solar cells (DSSCs). By exploiting the benefits of both structural and compositional characteristics, namely, the direct electrical pathways of 1D nanostructure, optimized work function of metal alloy as well as the synergistic effect between Ni3S4 and PtCo, the as-designed Ni3S4-PtCo heteronanorods exhibit excellent catalytic activity and stability toward the reduction of triiodide in DSSCs. A DSSC with Ni3S4-PtCo achieves a high power conversion efficiency of 8.66% under AM1.5G illumination (100 mW cm−2), higher than that of pristine Pt-based device (8.12%). Moreover, the fast activity onset and relatively long stability further demonstrate that the Ni3S4-PtCo heteronanorod is a promising alternative to Pt in DSSCs. Considering the diversity of structures and components in heterostructures, the strategy presented here can be extended for synthesizing other well-defined 1D M-S heterojunctions, which may be used in the fields of catalysis, energy conversion and storage.

The interfaces between perovskite and charge transport layers greatly impact the device efficiency and stability of perovskite solar cells (PSCs). Inserting an ultrathin wide-band-gap layer between perovskite and hole transport layers (HTLs) has recently been shown as an effective strategy to enhance device performance. Herein, a small amount of an organic halide salt, N,N'-dimethylethylene-1,2-diammonium iodide, is used to create two-dimensional (2D)-three-dimensional (3D) heterojunctions on MAPbI3 thin film surfaces by facile solution processing. The formation of an ultrathin wide-band-gap 2D perovskite layer on top of 3D MAPbI3 changes the morphological and photophysical properties of perovskite thin films, effectively reduces the surface defects, and suppresses the charge recombination in the interfaces between perovskite and HTL. As a result, a power conversion efficiency of ∼20.2%, with an open-circuit voltage of 1.14 V, a short-circuit current density of 22.57 mA cm-2, and a fill factor of 0.78, is achieved for PSCs with enhanced stability.

The rich chemistry of metal halide perovskites has enabled various methods of band structure control and surface passivation. Here we report a highly facile and efficient post-treatment approach for precise color tuning of cesium lead halide perovskite nanocrystals (NCs) with enhanced stability. By utilizing a special multifunctional organic ligand, triphenyl(9-phenyl-9H-carbazol-3-yl)phosphonium bromide (TPP-Carz), carbon-halide bond cleavage can be achieved to release halide ions from halogenated solvents in a controlled manner for color tuning of perovskite NCs via ion exchange. Besides controlled release of halide ions for anion exchange, TPP-Carz can effectively passivate the surfaces of perovskite NCs simultaneously. As a result, perovskite NCs prepared by this post-treatment method with tunable colors over the entire visible spectrum have shown significantly improved luminescence and stability in comparison to the ones prepared using reactive anion precursors without surface passivation by TPP-Carz.

A hollow nanostructure enables color tuning of metal halide perovskites with efficient blue emissions from cesium lead bromide., Metal halide perovskite nanocrystals (NCs) have emerged as new-generation light-emitting materials with narrow emissions and high photoluminescence quantum efficiencies (PLQEs). Various types of perovskite NCs, e.g., platelets, wires, and cubes, have been discovered to exhibit tunable emissions across the whole visible spectrum. Despite remarkable advances in the field of perovskite NCs, many nanostructures in inorganic NCs have not yet been realized in metal halide perovskites, and producing highly efficient blue-emitting perovskite NCs remains challenging and of great interest. Here, we report the discovery of highly efficient blue-emitting cesium lead bromide (CsPbBr3) perovskite hollow NCs. By facile solution processing of CsPbBr3 precursor solution containing ethylenediammonium bromide and sodium bromide, in situ formation of hollow CsPbBr3 NCs with controlled particle and pore sizes is realized. Synthetic control of hollow nanostructures with quantum confinement effect results in color tuning of CsPbBr3 NCs from green to blue, with high PLQEs of up to 81%.

Electrochemical splitting of water is one of the most reliable and effective ways for the sustainable production of pure hydrogen on a large scale, while the core of this technology lies in the development of highly active non-noble-metal-based electrocatalysts to lower the large dynamic overpotentials of electrode materials. Here, an interface engineering strategy is demonstrated to construct an efficient and stable catalyst based on NiS@MoS2 core-shell hierarchical microspheres for the hydrogen evolution reactions (HER). The ultrathin MoS2 nanosheets in-situ grow on the surface of NiS hierarchical micro-sized spheres constructed by porous nanoplates, endowing the composites with rich interfaces, well-exposed electroactive edges, high structural porosity and fast transport channels. These advantages are favorable for the improvement of catalytic sites and the transport of catalysis-relevant species. More importantly, the intimate contact between MoS2 nanosheets and NiS nanoplates synergistically favors the chemical sorption of hydrogen intermediates, thereby reducing the reaction barrier and accelerating the HER catalytic process. As a result, the optimized NiS@MoS2 catalyst manifests impressive HER activity and durability, with a low overpotential of 208 mV in 0.5 M H2SO4 and 146 mV in 1.0 M KOH at 10 mA cm−2, respectively. This work not only provides an effective way to construct core-shell hierarchical microspheres but also a multiscale strategy to regulate the electronic structure of heterostructured materials for energy-related applications.

Wurtz-stannite Cu2CdGeS4 nanocrystals were synthesized via a facile hot-injection method at a low temperature. They exhibited low charge transfer resistance at the electrolyte-electrode interface and high electrocatalytic activity for the reduction of I3(-) in dye-sensitized solar cells (DSSCs). Moreover, this DSSC showed a power conversion efficiency of 7.67%, comparable to the Pt-based device (7.54%).

Hierarchical Cu2−XSe nanotubes, constructed by nanosheets with a thickness of two unit cells (1.2 nm), have been fabricated with Cu(OH)2 nanorod arrays as self-sacrificial templates at room temperature, with a high surface area of 72.3 m2 g−1. The unique structure of the Cu2−XSe nanotubes leads to high electrocatalytic activity towards the reduction of polysulfides, given their enlarged active surface area, rapid transportation of electrons and mass. As a result, quantum dot-sensitized solar cells (QDSSCs) with the obtained Cu2−XSe nanotubes as the counter electrode material exhibit long-term stability and a high power conversion efficiency of 5.14% (1 sun irradiation simulation), better than those of the commonly-used Cu2S/brass (3.38%) and reference Pt (1.78%) electrodes.

In this work, a series of nano- and microcrystals of anatase TiO2 including well-defined truncated tetragonal bipyramids (TTBs) (15–20 nm) and hierarchical hollow microspheres (HHMs) (1.5 μm) were successfully synthesized using a facile sol-hydrothermal approach free from surfactants and templates. The latter HHMs also consisted of similar TTBs but bigger in size. The conversion pathway to TiO2 mainly depended on the volume ratio of H2O2 to NH3. In the presence of NH4F, small TTBs were generated as a result of inhibited growth along both [100] and [001] directions. The formation of HHMs through gradual depletion of the yolk followed a typical Ostwald ripening process. Their photovoltaic activities were investigated on dye-sensitized solar cells (DSSCs) using bilayer photoanodes made of typical TTBs and HHMs. The cells delivered a power conversion efficiency (PCE) of 9.06%, corresponding to a 51.5% increment over those fabricated in the same way using P25 and 400 nm TiO2 (CCIC). Meanwhile, the short-circuit current density (JSC) reached up to 18.38 mA cm−2, which was 1.46 times that of the P25 + CCIC cells. They were also superior to previously reported DSSCs based on highly crystalline nanooctahedra and agglutinated mesoporous microspheres. The small particle size of TTBs and micrometer size and hierarchical structure of HHMs endowed the bilayer photoanodes with a synergetic effect of dye loading and light scattering. Moreover, their exposed {001} and {101} facets, which could facilitate spontaneous charge separation through preferential carrier flow towards specific facets, and highly crystalline anatase phase rendered the cells efficient in charge collection.

As a kind of promising generation solar cells, the catalytic properties of counter electrodes (CEs) play a key factor on the performance of QDSSCs (quantum dot-sensitized solar cells) at present. Here, hierarchical Cu7S4 nanotubes (Cu7S4-HNT) assembled by hexagonal nanoplates have been prepared by an in-situ growth route and etching process at room temperature. The formation mechanism of the unique morphology is also proposed. Because of the rapid diffusion of electrons and electrolyte, abundant catalytic sites and high stability, the as-prepared Cu7S4-HNT combined the characteristics of nanotube and hierarchical structure can improve the catalytic performance of CEs. QDSSCs based on the Cu7S4-HNT CEs possess a high power conversion efficiency of 4.53%, superior to those with the commonly used Cu2S/brass (3.3%) or the referenced Pt (1.79%) CEs. What's more, the Cu7S4-HNT CE still shows excellent stability in electrolyte after 1000 CV cycles.

Mastery over the structures at nano/microscale can effectively tailor the catalytic activity and durability of materials. Herein, three dimension (3D) hierarchical iron diselenide (FeSe2) microspheres have been successfully synthesized via a hot-injection method. The morphologies of building blocks and final products can be simply controlled by the amount and/or the type of alkythiols, from irregular micro/nanoparticles to uniform 3D hierarchical microspheres made of ultrathin nanosheets or rhombus-like nanorods. A formation mechanism has been understood based on the inherent crystal structure of FeSe2 and the selective adsorption of alkythiols. The as-obtained FeSe2 samples were employed as counter electrode (CE) materials in dye-sensitized solar cells (DSSCs). Electrochemical characterizations indicated that the 3D hierarchical FeSe2 microspheres composed of ultrathin nanosheets (FeSe2 NSs) exhibited low charge transfer resistance at the electrolyte–electrode interface, high electrocatalytic activity and fast reaction kinetics for the I−/I3− redox reaction. A DSSC with FeSe2 NSs CE achieved a high power conversion efficiency of 8.39% under a simulated solar illumination of 100 mW cm−2 (AM 1.5), comparable to that of Pt based devices (8.20%). Moreover, the fast activity onset and relatively long stability demonstrated that the FeSe2 NSs is a promising alternative to Pt in DSSC.

The widely used brass based Cu 2 S counter electrodes (CEs) cannot stand the continuing corrosion in polysulfide electrolyte, which has limited the development of quantum dot-sensitized solar cells. Here, skeletal Cu 7 S 4 nanocages (SKE-Cu 7 S 4 ) with symmetric opening windows were rational designed and synthesized by kinetic roughening processes, and a possible formation mechanism had been proposed. Furthermore, SKE-Cu 7 S 4 onto fluorine-doped tin oxide glass substrates were designed and deposited to function as new efficient, stable and low cost CEs. Thanks to the 3D opening structure of SKE-Cu 7 S 4 CEs, the assembled QDSSCs exhibited a power conversion efficiency of 4.43% under 1 sun (100 mW cm −2 ) irradiation, while those of preformed 18 facet-Cu 7 S 4 , Pt and brass/Cu 2 S CEs are of 3.87%, 1.73% and 3.32%, respectively. Further studies by cyclic voltammetry measurements indicate the SKE-Cu 7 S 4 CEs still remain good cyclability after 600 cycles, demonstrating a super stable capability, while the commonly used brass/Cu 2 S CEs show obvious fluctuation.