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1.
J Colloid Interface Sci ; 573: 78-86, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32259694

RESUMO

Inorganic p-type materials show great potential as the hole transport layer in perovskite solar cells with the merits of low costs and enhanced chemical stability. As a p-type material, cobalt oxide (CoO) has received so far not that level of attention despite its high hole mobility. Herein, solution-processed p-type CoO nanocrystalline films are developed for inverted mixed perovskite solar cells. The ultrafine CoO nanocrystals are synthesized via an oil phase method, which are subsequently treated by a ligand exchange process using pyridine solvent to remove the long alkyl chains covering the nanocrystals. From this homogeneous colloidal solution CoO films are obtained, which exhibit a smooth and pin-hole free surface morphology with high transparency and good conductivity. The ultraviolet photoelectron spectrum also indicates that the energy levels of the CoO film match well with the mixed perovskite Cs0.05(FA0.83MA0.17)0.95(I0.83Br0.17)3. Inverted solar cells based on crystalline CoO films with ligand exchange show a reasonable energy conversion efficiency, whereas devices based on CoO films without ligand exchange suffer from a strong S-shape JV-characteristic. Thus, the crystalline CoO films are foreseen to pave a new way of inorganic hole transport materials in the fields of perovskite solar cells.

2.
Dalton Trans ; 48(33): 12386-12390, 2019 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-31397458

RESUMO

A Ga/Ga2O3@C dodecahedron composite with a high specific capacity of about 542 mA h g-1 after 200 cycles at the current density of 1000 mA g-1 was synthesized by one-step hydrogen reduction. This hierarchical homogeneous structure combined the Ga, Ga2O3 and carbon frameworks (from Ga-MOF) to exhibit excellent electrochemical performance.

3.
Dalton Trans ; 48(27): 10191-10198, 2019 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-31190031

RESUMO

In this work, we synthesized a novel UIO-67@Se@PANI composite cathode material for Li-Se battery applications. Zr-MOFs (metal organic frameworks) were used as a support and a PANI (polyaniline) layer was employed as the coating. UIO-67@Se@PANI was expected to be one of the candidates for Li-Se batteries, with a high specific capacity of 248.3 mA h g-1 at 1C (1C = 675 mA g-1) after 100 cycles. In particular, stable capacities of 203.1 and 167.6 mA h g-1 were received after 100 cycles at high rates of 2C and 5C, respectively. To explain such a good electrochemistry performance of the composite cathode material, multiple characterization methods were carried out. And that can be attributed to the sandwich-like structure of the UIO-67@Se@PANI composite and the fact that UIO-67 can provide unsaturated sites to tether the selenium effectively and the PANI layer can improve the electronic conductivity of the whole electrode significantly.

4.
Dalton Trans ; 48(5): 1906-1914, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30656345

RESUMO

Bi2S3 is a promising negative electrode material for lithium storage owing to its high theoretical capacity. Nevertheless, the capacity of Bi2S3 decays very rapidly upon Li cycling. Here, Bi2S3 and Bi2S3/C were successfully synthesized by a novel route. Sulfur powder as a kind of sulfur source reacted with a metal organic framework based on bismuth and trimesinic acid-Bi(BTC)(DMF)·DMF·(CH3OH)2 (denoted as Bi-BTC). Trimesic acid further acted as a new type of carbon source to synthesize the Bi2S3/C composite. The particle sizes of the composite were smaller than those of pure Bi2S3, showing the suppression of Bi2S3 aggregation. Charge-discharge performance and cyclability for both the Bi2S3 and Bi2S3/C composites in lithium-ion batteries were measured. Specifically, the specific capacities of Bi2S3/C and Bi2S3 reached 765 and 603 mA h g-1, respectively, at 100 mA g-1 after 100 cycles. Because of its high capacity and excellent cycle life, Bi2S3/C is a promising energy storage material.

5.
J Nanosci Nanotechnol ; 19(1): 263-267, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30327034

RESUMO

The new demands for energy storage systems have been placed with demands for flexible wearable electronics. Herein, rugby-like GeO2 nanoparticles (NPs) have been directly grown on carbon cloth (GeO2 NPs/CC) through a one-step hydrolysis process at room temperature, which can be used as a self-supporting flexible anode for lithium ion battery (LIBs). The rugby-like GeO2 NPs/CC showed an improved lithium-storage performance with features of high reversible capacity ~2000 mA·h·g-1 even after 100 cycles and good cycling stability. Besides, its initial coulomb efficiency (79.1%) was also enhanced compared to that of some reported GeO2-based materials.

6.
ACS Appl Mater Interfaces ; 10(41): 35385-35394, 2018 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-30152674

RESUMO

One major drawback that prevents the large-scale practical implementation of perovskites is their susceptibility to performance degradation in humid environments. Here, we achieved uniform, stable perovskite films within a polyvinylpyrrolidone (PVP) polymer frame via mild solution processing in ambient air with over 60% relative humidity. In addition to facilitating film formation, the hydrophobic PVP served to protect the perovskite grains from atmospheric moisture. Use of PVP, coupled with optimization of the deposition parameters, provided for compact, smooth, pinhole-free perovskite films that when incorporated into a photovoltaic device exhibited highly reproducible efficiencies in the range of up to 17%. In the absence of encapsulation, the devices exhibited stable performance characteristics during exposure to humid ambient air for 600 h. Furthermore, on flexible substrates, the 8 wt % PVP-perovskite samples provided for device efficiencies of ca. 15%. The devices retained ca. 73% of their efficiency after bending 1000 times with a bending radius of 0.5 cm.

7.
ACS Appl Mater Interfaces ; 9(50): 43724-43732, 2017 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-29182302

RESUMO

Mesoporous titania is a cheap and widely used material for photovoltaic applications. To enable a large-scale fabrication and a controllable pore size, we combined a block copolymer-assisted sol-gel route with spray coating to fabricate titania films, in which the block copolymer polystyrene-block-poly(ethylene oxide) (PS-b-PEO) is used as a structure-directing template. Both the macroscale and nanoscale are studied. The kinetics and thermodynamics of the spray deposition processes are simulated on a macroscale, which shows a good agreement with the large-scale morphology of the spray-coated films obtained in practice. On the nanoscale, the structure evolution of the titania films is probed with in situ grazing incidence small-angle X-ray scattering (GISAXS) during the spray process. The changes of the PS domain size depend not only on micellization but also on solvent evaporation during the spray coating. Perovskite (CH3NH3PbI3) solar cells (PSCs) based on sprayed titania film are fabricated, which showcases the suitability of spray-deposited titania films for PSCs.

8.
Nanoscale ; 5(24): 12574-81, 2013 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-24173030

RESUMO

TiO2 microspheres assembled by single crystalline rutile TiO2 nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous-organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 µm by adjusting the volume of the reactant water. Nitrogen adsorption-desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m(2) g(-1). The 1 µm sized TiO2 nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO2. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering centers.

9.
ACS Appl Mater Interfaces ; 5(22): 11858-64, 2013 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-24160726

RESUMO

CuInS2 quantum-dot sensitized TiO2 photoanodes with In2S3 buffer layer were in situ prepared via chemical bath deposition of In2S3, where the Cd-free In2S3 layer then reacted with TiO2/CuxS which employed a facile SILAR process to deposit CuxS quantum dots on TiO2 film, followed by a covering process with ZnS layer. Polysulfide electrolyte and Cu2S on FTO glass counter electrode were used to provide higher photovoltaic performance of the constructed devices. The characteristics of the quantum dots sensitized solar cells were studied in more detail by optical measurements, photocurrent-voltage performance measurements, and impedance spectroscopy. On the basis of optimal CuxS SILAR cycles, the best photovoltaic performance with power conversion efficiency (η) of 1.62% (Jsc = 6.49 mA cm(-2), Voc = 0.50 V, FF = 0.50) under full one-sun illumination was achieved by using Cu2S counter electrode. Cu2S-FTO electrode exhibits superior electrocatalytic ability for the polysulfide redox reactions relative to that of Pt-FTO electrode.

10.
Chem Asian J ; 7(10): 2313-20, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22890917

RESUMO

Anatase TiO(2) nanorods with large specific surface areas and high crystallinity have been synthesized by surfactant-free hydrothermal treatment of water-soluble peroxotitanium acid (PTA). X-ray diffraction and TEM analysis showed that all TiO(2) nanorods derived from PTA in different hydrothermal processes were in the anatase phase, and high aspect ratio TiO(2) nanorods with chain-shaped structures were formed at 150 °C for 24 h by oriented growth. The nanorods were fabricated as photoanodes for high-efficiency dye-sensitized solar cells (DSSCs). DSSCs fabricated from the chain-shaped TiO(2) nanorods gave a highest short-circuit current density of 14.8 mA cm(-2) and a maximum energy conversion efficiency of 7.28 %, as a result of the presence of far fewer surface defects and grain boundaries than are present in commercial P25 TiO(2) nanoparticles. Electrochemical impedance spectroscopy also confirmed that DSSCs based on the TiO(2) nanorods have enhanced electron transport properties and a long electron lifetime.

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