Qingjiang Yu

A stable and efficient quasi-solid-state dye-sensitized solar cell with a low molecular weight organic gelator

High power conversion efficiency and long-term stability are significant targets for practical applications of dye-sensitized solar cells. Here, we present a quasi-solid-state dye-sensitized solar cell that incorporates a low molecular weight organic gelator-based electrolyte in conjunction with a high-absorptivity ruthenium sensitizer C105, exhibiting an impressive power conversion efficiency of 9.1%. By means of transient absorption and electrical impedance measurements, we scrutinize the impacts of the additive low molecular weight organic gelator in a low-volatility 3-methoxypropionitrile electrolyte on the photovoltaic characteristics of dye-sensitized solar cells with a sensitizer C105. The quasi-solid-state dye-sensitized solar cell also retains excellent thermal and light-soaking stability during 1000-h accelerated aging tests.

Ultralong Rutile TiO2 Nanowire Arrays for Highly Efficient Dye-Sensitized Solar Cells.

Vertically aligned rutile TiO2 nanowire arrays (NWAs) with lengths of ∼44 μm have been successfully synthesized on transparent, conductive fluorine-doped tin oxide (FTO) glass by a facile one-step solvothermal method. The length and wire-to-wire distance of NWAs can be controlled by adjusting the ethanol content in the reaction solution. By employing optimized rutile TiO2 NWAs for dye-sensitized solar cells (DSCs), a remarkable power conversion efficiency (PCE) of 8.9% is achieved. Moreover, in combination with a light-scattering layer, the performance of a rutile TiO2 NWAs based DSC can be further enhanced, reaching an impressive PCE of 9.6%, which is the highest efficiency for rutile TiO2 NWA based DSCs so far.

Gas sensing properties of self-assembled ZnO nanotube bundles

Large-scale ZnO nanotube bundles were synthesized by a simple solution-based method under mild conditions. The structural and optical properties of the resultant products were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption and photoluminescence techniques. The sensor based on the ZnO nanotube bundles exhibited excellent sensing properties against ethanol gas at the operating temperature of 230 °C. The sensitivity of the sensor to 100 ppm ethanol was approximate 25.2 with a rapid response time (about 3 s). It was found that the ZnO nanotube bundle sensor displayed significantly better sensing performances due to a larger surface area and more electron donor related oxygen vacancies in comparison with the ZnO nanorod bundle sensor.

Zinc-doped SnO2 nanocrystals as photoanode materials for highly efficient dye-sensitized solar cells

Zn-doped SnO2 nanocrystals were successfully synthesized by a simple hydrothermal method. It is found that Zn doping into SnO2 can induce a negative shift in the flat-band potential (VFB) and increase the isoelectric point. As a result, dye-sensitized solar cells (DSCs) based on Zn-doped SnO2 nanocrystal photoanodes exhibit longer electron lifetimes and higher dye loading compared to undoped SnO2 based DSCs. The overall power conversion efficiency (η) of the optimized Zn-doped SnO2 based DSC reaches 4.18% and increases to 7.70% after the TiCl4 treatment. More importantly, a remarkable η of 8.23% is achieved for DSCs based on a high-quality double-layer SnO2 photoanode with the TiCl4 treatment, to the best of our knowledge, which is so far the best reported efficiency for DSCs based on SnO2 photoanodes.

Graphene nanosheets inserted by silver nanoparticles as zero-dimensional nanospacers for dye sensitized solar cells

Three-dimensional Ag nanoparticle/GNs (Ag/GNs) hybrids as highly efficient counter electrode (CE) materials for dye sensitized solar cells (DSSCs) is described, highlighting the Ag nanoparticles as zero-dimensional nanospacers inserting into GNs to lift the interspacing layer between individual GNs. It is demonstrated that, when the hybrids are used as CE materials for DSSCs, compared to their pure GNs, Ag/GNs hybrids without agglomerates have a significant improvement in their electrochemical properties such as high current density, narrow peak-to-peak separation (Epp) and low charge transfer resistance (RCT). The enhancement of electrochemical performance can be attributed to the increased electrode conductivity, an extended interlayer distance and the reduction of the restacking of graphene sheets due to the insertion of metallic Ag nanoparticles into GNs. The DSSC with this hybrid CE exhibited an energy conversion efficiency (η) of 7.72% with an open circuit voltage (VOC), short circuit photocurrent density (JSC), and fill factor (FF) of 732 mV, 14.67 mA cm(-2), and 71.8%, respectively.

Efficient photocatalyst based on ZnO nanorod arrays/p-type boron-doped-diamond heterojunction

The ZnO nanorod arrays (NRs) have been fabricated on p-type boron-doped diamond (BDD) substrate by hydrothermal method. It was demonstrated that the density and diameter of the ZnO NRs can be effectively controlled by adjusting the reactant concentration. Photocatalytic activity of the fabricated ZnO NRs/p-BDD heterojunction was investigated for the degradation of methyl orange dye and the results indicated that diameter and density of ZnO NRs play a very important role in photocatalytic degradation. Furthermore, the ZnO NRs/p-BDD heterostructure photocatalysts are easily recycled and reused.

Very high quantum efficiency in InAs/GaSb superlattice for very long wavelength detection with cutoff of 21 μm

The authors report the dependence of the quantum efficiency on beryllium concentration in the active region of type-II InAs/GaSb superlattice infrared detector with a cutoff wavelength around 21 μm. It is found that the quantum efficiency and responsivity show a clear delineation in comparison to the doping concentration. The quantum efficiency is further improved by gradually doping in the absorbing region. At 77 K, the 50% cutoff wavelength of the VLWIR detector is 18 μm, and the R0A is kept at a stable value of 6 Ω cm2. Different beryllium concentration leads to an increase of an average quantum efficiency in the 8–15 μm window from 35% to 55% with a π-region thickness of 3.0 μm, for Ubias = −0.3 V, and no anti-reflection coating. As for a further result, the quantum efficiency reaches at a maximum value of 66% by gradually doping in the absorbing region with the peak detectivity of 3.33 × 1010 cm Hz1/2/W at 15 μm.

One-pot synthesis of hierarchical SnO2 hollow nanospindles self-assembled from nanorods and their lithium storage properties

Novel hierarchical SnO2 hollow nanospindles self-assembled from nanorods have been successfully synthesized via a templating approach under hydrothermal conditions. The influence of the reactant concentration on SnO2 products is investigated in detail. It is found that the interplay of the acidic etching of Fe2O3 templates and controlled hydrolysis of SnCl2 is significant for the formation of the hierarchical SnO2 hollow nanostructures. The evolution process and formation mechanism of the hollow structures with nanorods are analyzed from the angle of nucleation and morphology. Moreover, the electrochemical properties of the hollow structures are also studied by charge–discharge cycling, the result displays that the hierarchical SnO2 hollow nanostructure exhibits much better lithium storage properties with higher reversible capacities and enhanced cyclic capacity retention than the commercial SnO2 nanoparticles.

Heterostructured TiO2/MgO nanowire arrays for self-powered UV photodetectors

Heterostructured TiO2/MgO nanowire arrays (NWAs) were grown vertically on fluorine-doped tin oxide (FTO) glass by a simple solvothermal method. A photoelectrochemical self-powered UV photodetector (UVPD) was fabricated using the heterostructured TiO2/MgO nanowire arrays (NWAs) as the photoanode. The TiO2/MgO NWAs based UVPDs shows a higher photocurrent density (J) and open-circuit voltage (Voc) with respect to the UVPD with bare TiO2 NWAs under UV light irradiance. The intrinsic role of the MgO shell layer on the J and Voc varitions of UVPDs is investigated in detail. An impressive responsivity of 0.233 A W−1 was achieved for the UVPD with TiO2/MgO NWAs, which is the highest responsivity for photoelectrochemical self-powered UVPDs based on various TiO2 nanostructured photoanodes so far. Moreover, this UVPD also exhibits a high on/off ratio, fast response time, excellent visible-blind characteristic and linear optical signal response.

An interfacial defect-controlled ZnO/PbS QDs/ZnS heterostructure based broadband photodetector

An in situ successive ionic layer adsorption and deposition method is introduced for fabrication of PbS QDs-on-ZnO heterostructures, which improves carriers transport within PbS QDs by eliminating the introduction of ligands. By suitably controlling the interface related defects characteristics through solvent adjustment, broadband photodetection ranging from 340 nm to 840 nm is achieved. Most significantly, improved device performance is achieved even in the case that no obvious type-II heterostructure is formed between ZnO and PbS, which reminds us of the significant role of QD, defects control besides their size, shape and ligands adjustments.