Jingting Zhu

Vanadium Dioxide Nanoparticle-based Thermochromic Smart Coating: High Luminous Transmittance, Excellent Solar Regulation Efficiency, and Near Room Temperature Phase Transition

An annealing-assisted preparation method of well-crystallized VxW1-xO2(M)@SiO2 core-shell nanoparticles for VO2-based thermochromic smart coatings (VTSC) is presented. The additional annealing process reduces the defect density of the initial hydrothermally prepared VxW1-xO2(M) nanoparticles and enhances their crystallinity so that the thermochromic film based on VxW1-xO2(M)@SiO2 nanoparticles can exhibit outstanding thermochromic performance with balanced solar regulation efficiency (ΔTsol) of 17.3%, luminous transmittance (Tlum) up to 52.2%, and critical phase transition temperature (Tc) around 40.4 °C, which is very promising for practical application. Furthermore, it makes great progress in reducing Tc of VTSC to near room temperature (25.2 °C) and simutaneously maintaining excellent optical properties (ΔTsol = 14.7% and Tlum = 50.6%). Such thermochromic performance is good enough to make VTSC applicable to practical architecture.

Achieving high-performance planar perovskite solar cells with co-sputtered Co-doping NiOx hole transport layers by efficient extraction and enhanced mobility

Perovskite solar cells are some of the most promising photovoltaic devices and they have experienced extraordinary progress in efficiency and fabricating technologies. Herein, we explore the effect of Co-doped NiOx hole transport layers on the electronic structure and photovoltaic properties of PSCs, which were deposited onto FTO substrates via DC magnetron sputtering at room temperature. Appropriate Co-doping can slightly regulate the optical band gap and the Fermi level position, leading to an increased potential cell performance. By virtue of continuously adjusting the power loaded onto the Co target, we can obtain the optimal atomic ratio of the Co:NiOx hole transport layer, and the PSC based on Co:NiOx exhibited a 25% higher efficiency than its undoped counterparts (from 9.46% to 12.61%). Therefore, these results demonstrate that Co is an appropriate dopant and the PSCs based on Co:NiOx layers have a good performance.

Synthesis of novel ammonium vanadium bronze (NH4)0.6V2O5 and its application in Li-ion battery

A novel ammonium vanadium bronze (NH4)0.6V2O5 has been successfully synthesized via a simple hydrothermal treatment and its electrochemical performance is investigated. The as-synthesized material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrum, Raman spectrum, X-ray photoelectron spectroscopy (XPS), element analysis (EA), cyclic voltammetry (CV) and galvanostatic charge/discharge cycling test. The results revealed that a pure novel phase (NH4)0.6V2O5 was obtained with square brick-like morphology. Preparation conditions such as amount of reducing agent, temperature and reaction time have been investigated to obtain the pure phase. (NH4)0.6V2O5 square bricks are tested as a cathode material for lithium-ion batteries. It has an excellent lithium ion insertion/extraction ability with a high specific discharge capacity of 280.2 mA h g−1 and 244.3 mA h g−1 during 1.0–3.8 V at the current densities of 10 mA g−1 and 20 mA g−1, respectively.

Solar-thermochromism of a hybrid film of VO2 nanoparticles and CoII–Br–TMP complexes

A hybrid film consisting of VO2 nanoparticles and CoII–Br–TMP complexes was prepared. The CoII–Br–TMP complexes containing cobalt(II), trimethylolpropane (CH3CH2C(CH2OH)3, TMP) and bromine were selected to be combined with VO2 nanoparticles for the first time. Evident colour-change behaviour in response to temperature change and enhanced optical performance of this composite were reported.

Hybrid films of VO2 nanoparticles and a nickel(II)-based ligand exchange thermochromic system: excellent optical performance with a temperature responsive colour change

It is well known that excellent optical performance is a vital factor of vanadium dioxide (VO2) thermochromic films. Except for optimizing the properties of VO2 itself as most researchers have been focusing on, hybridizing has been verified to be an effective way to substantially improve the solar regulation efficiency (ΔTsol) and luminous transmittance (Tlum) of the thermochromic films. Therefore, a nickel(II)-based ligand exchange thermochromic system (NLETS), which contains nickel(II), 2,2-dimethylpropane-1,3-diol ((CH3)2C(CH2OH)2) and bromide, is selected in this paper to be combined with VO2 nanoparticles forming a hybrid film. Compared with a pure VO2 film, this novel scheme demonstrates a 127% increase (from 8.02% to 18.19%) in ΔTsol at a rather high Tlum (Tlum,l = 73.36% and Tlum,h = 68.71%). What is more, since the intrinsic colour change of the NLETS from colourless to blue, the hybrid film presents an evident temperature responsive colour change: from yellow to green, which is crucial for exhibition, publicity and promotion of thermochromic products.

Achieving High Current Density of Perovskite Solar Cells by Modulating the Dominated Facets of Room-Temperature DC Magnetron Sputtered TiO2 Electron Extraction Layer

The short circuit current density of perovskite solar cell (PSC) was boosted by modulating the dominated plane facets of TiO2 electron transport layer (ETL). Under optimized condition, TiO2 with dominant {001} facets showed (i) low incident light loss, (ii) highly smooth surface and excellent wettability for precursor solution, (iii) efficient electron extraction, and (iv) high conductivity in perovskite photovoltaic application. A current density of 24.19 mA cm-2 was achieved as a value near the maximum limit. The power conversion efficiency was improved to 17.25%, which was the record value of PSCs with DC magnetron sputtered carrier transport layer. What is more, the room-temperature process had a great significance for the cost reduction and flexible application of PSCs.

High Performance and Enhanced Durability of Thermochromic Films Using VO2@ZnO Core–Shell Nanoparticles

For VO2-based thermochromic smart windows, high luminous transmittance (Tlum) and solar regulation efficiency (ΔTsol) are usually pursued as the most critical issues, which have been discussed in numerous researches. However, environmental durability, which has rarely been considered, is also so vital for practical application because it determines lifetime and cycle times of smart windows. In this paper, we report novel VO2@ZnO core-shell nanoparticles with ultrahigh durability as well as improved thermochromic performance. The VO2@ZnO nanoparticles-based thermochromic film exhibits a robust durability that the ΔTsol keeps 77% (from 19.1% to 14.7%) after 103 hours in a hyperthermal and humid environment, while a relevant property of uncoated VO2 nanoparticles-based film badly deteriorates after 30 h. Meanwhile, compared with the uncoated VO2-based film, the VO2@ZnO-based film demonstrates an 11.0% increase (from 17.2% to 19.1%) in ΔTsol and a 31.1% increase (from 38.9% to 51.0%) in Tlum. Such integrated thermochromic performance expresses good potential for practical application of VO2-based smart windows.

Mesostructured perovskite solar cells based on highly ordered TiO2 network scaffold via anodization of Ti thin film

An anodized TiO2 interconnected network was fabricated and utilized as a mesoporous scaffold and electron transporter in perovskite solar cells. By modifying the synthesis parameters, the morphological features of the interconnected TiO2 nanostructures can be widely tuned and precisely controlled. The functional properties of the anodized TiO2 network are found to be severely influenced by morphology as well as the extent of oxidation. The device with the optimized TiO2 network exhibits superior electron extraction and transferability, resulting in conspicuous enhancement of the photocurrent and power conversion efficiency (PCE). This work proposes a promising and facile method for improving the performance of perovskite solar cells.

Fast Fabrication of a Stable Perovskite Solar Cell with an Ultrathin Effective Novel Inorganic Hole Transport Layer

With the aim of fabricating simple, reproducible, and scalable perovskite solar cells (PSCs) with least time consumption, a novel CoOx hole transport layer (HTL) was first proposed and introduced in this work. The CoOx HTL thickness was minimized to about 10 nm with complete coverage on the FTO substrate (F-doped SnO2) by direct current magnetron sputtering. The ultrathin HTL could minimize the incident light loss caused by cobalt ion absorption and reduce the carrier transport loss by shortening the transport path. Copper was incorporated into the CoOx lattice to address the low conductivity of the CoOx film and the energy-level mismatch between CoOx and the perovskite material. On the basis of cobalt-copper binary oxide (Co1-yCuyOx), the highest power conversion efficiency (PCE) of about 10% was achieved, which was acceptable for mass production. Moreover, the deposition of such Co1-yCuyOx films takes only 2 min without size limitation of substrates. A well-functioned device based on the Co1-yCuyOx HTL could hence be fabricated within 100 min. Excellent stability was demonstrated as well, with over 90% of the initial PCE remaining after being stored in a dark and humid environment (relative humidity 60%) for 12 days.

Synthesis and formation mechanism of 1D hollow SiO2 nanomaterials using in situ formed 1D NaCl crystal templates

One dimensional (1D) hollow silica nanomaterials are, for the first time, successfully prepared using in situ formed water-soluble NaCl 1D crystals as templates. The formation mechanism of the 1D NaCl crystals and the 1D hollow SiO2 nanomaterials is systematically studied. This new approach may open up new opportunities in the synthesis of novel anisotropic nanomaterials, the construction of nanodevices, and have potential applications in drug delivery.