Sihang Bai

One-pot stirring-free synthesis of silver nanowires with tunable lengths and diameters via a Fe3+ & Cl− co-mediated polyol method and their application as transparent conductive films

The properties of nanomaterials are highly dependent on their size, shape and composition. Compared with zero-dimensional nanoparticles, the increased dimension of a one-dimensional silver nanowire (AgNW/Ag NW) leads to extra challenges on synthesizing it with controllable sizes. Here, a convenient way for the synthesis of AgNWs with tunable sizes has been developed simply by adjusting the amount of salt additives, i.e., ferric chloride (FeCl3), or Fe(NO3)3 & KCl. The average diameter and length of nanowires are readily tailored within 45-220 nm and 10-230 μm, respectively. The distinctive roles of Fe3+ and Cl- played during the growth stages of Ag NWs were revealed by comparative experiments and a heterogeneous nucleation model with the assistance of oxidative etching was proposed to elucidate the growth mechanism. Afterwards, transformations in XRD patterns from nanometer-size effects and quantitative relation for size-dependent peak wavelength of surface plasmon resonances (SPRs) in UV-vis spectroscopy of these nanowires were studied. In addition, as transparent conductive materials (TCMs), these metal nanowires were utilized to fabricate transparent conductive films (TCFs), and the effects of their diameters and lengths were elucidated. Very/ultra-long nanowires with a high aspect ratio up to 1600 achieved impressive properties of R = 12.4 ohm sq-1 at T% = 90.1% without any post treatment. This facile method for the size-tunable growth of uniform AgNWs with high yield is attractive and ready to be home-made, which is believed to promote research in their potential applications, especially in optoelectronic devices and flexible electronics.

Efficient dye-sensitized solar cells employing highly environmentally-friendly ubiquinone 10 based I2-free electrolyte inspired by photosynthesis

A highly environmentally-friendly ubiquinone 10 (UQ10) based I2-free electrolyte, which is inspired by photosynthesis, is employed in dye-sensitized solar cells (DSSCs) under 100 mW cm−2 (AM 1.5G) illumination. Profiting from this UQ10 based electrolyte a 10% increased power conversion efficiency of 8.18% is achieved compared with the traditional one containing I2 (7.44%). The superior performance of this UQ10 based electrolyte is mainly derived from the lower visible light wastage and high catalytic activity to the counter electrode as revealed by photoelectrochemical characterization. Moreover, being widely adopted in cardiovascular medicine and cosmetics, UQ10 is a very safe and low-cost choice for DSSCs. With the advantages of high power conversion efficiency, bio-safety, universal dye compatibility and diversity of molecular design, UQ10 is very promising to be widely applied in DSSCs, and perovskite based solar cells.

Hydrothermal synthesis of TiO2 nanoparticles doped with trace amounts of strontium, and their application as working electrodes for dye sensitized solar cells: tunable electrical properties & enhanced photo-conversion performance

Strontium (Sr) doped TiO2 nanoparticles are investigated with a view to studying the performance parameters of dye sensitized solar cells (DSSCs). Sr is used in trace levels (parts per million, ppm hereafter). The Sr doped TiO2 and undoped TiO2 nanoparticles are synthesized by the hydrothermal method and thin films of TiO2 electrodes are prepared using these particles (average grain size of 24 nm). The electrodes are characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), surface area (BET) and UV-vis absorption spectrometry. DSSCs are fabricated using the doped and undoped TiO2 nanoparticle photoanodes. Their photovoltaic characteristics are studied by employing J–V measurements and electrochemical impedance spectroscopy (EIS). XRD studies reveal that the doping of Sr into the TiO2 lattice slightly inhibits the growth of the particles and causes lattice distortions. The optical studies indicate a reduction in band-gap upon doping of TiO2 films and a simultaneous enhancement in the photocurrent density (Jsc) and the photovoltage (Voc). The photoanode doped with 50 ppm Sr exhibits the highest power conversion efficiency (PCE) of about 7.88% which is 12.73% higher than that of undoped TiO2 cells. The effect of the Sr dopant on electron transport is studied by using EIS measurements. An improvement in electron life time is observed on the doping of TiO2.

A methylene bridged bisimidazolium iodide based low-volatility electrolyte for efficient dye-sensitized solar cells

In this paper, we demonstrate that 1,1′-methylene bis(3-n-methylimidazolium) diiodide (MMIDI) can be used as an excellent alternative iodide source to conventional lithium iodide (LiI) in electrolyte for dye-sensitized solar cell (DSSC). The MMIDI is cheaper and shows much improved physical and chemical stability compared to LiI. Noticeably, smaller charge transfer resistance for the reduction of triiodide and longer electron lifetime are found in the DSSCs based on MMIDI electrolyte, which result in a 23% higher overall conversion efficiency (5.26%) than that based on LiI electrolyte (4.27%). When the initial MMIDI electrolyte is optimized with functional additives, a promising 6.24% conversion efficiency is achieved.