Improvement of dye-sensitized solar cells toward the broader light harvesting of the solar spectrum

Dye-sensitized solar cells (DSSCs) have been extensively evolved for the past two decades in order to improve their cell performance. From the commercialization point of view, the overall solar to electrical energy conversion efficiency should compete with other solar cells. But, due to structural restrictions of DSSC using the liquid electrolyte and a space requirement between two electrodes, the direct tandem construction of DSSCs by stacking of repeating units is highly limited. In this feature article, important research trials to overcome these barriers and a recent research trend to improve the light harvesting strategies mainly panchromatic engineering, various tandem approaches such as parallel tandem, series tandem, p-n tandem etc., have been briefly reviewed.close271

Effect of sulphur vacancy on geometric and electronic structure of MoS2 induced by molecular hydrogen treatment at room temperature

Investigations into the interaction between molecular hydrogen and molybdenum disulphide have been in increasing demand to improve the understanding of the hydrodesulphurisation process, especially the creation of sulphur vacancies which result in coordinatively unsaturated sites in MoS 2. Here we present comprehensive studies of the structural and electronic modulation caused by exposure of MoS2 to H2 over a low temperature range, which may be helpful for industrial applications. Detail investigations were conducted with Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), and electrical transport properties as a function of H2 gas pressure up to 24 bar from 295 K to 350 K. Upon exposure to H2, we observed bond-softening using Raman spectroscopy, a decrease in d-spacing from the TEM results, and an increase in conductance, all of which are consistent with the first-principles calculations. The results demonstrate the formation of sulphur vacancies even under low H2 pressure at low temperature.close2

Efficient fiber-shaped perovskite photovoltaics using silver nanowires as top electrode

Methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell in a flexible fiber shape is developed via a fully dipping process with a mixed solvent of N, N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) followed by toluene dipping. We introduce the first-ever effective n-type compact layer through facile anodizing of titanium wire, achieving a considerable power conversion efficiency of 3.85%, which remains stable during bending; spray-deposited silver nanowires (Ag NWs) are used as the top electrode instead of gold. The ease of fabrication, low cost of materials, and all-solid-state structures result in a simple approach to developing electronic textiles for harvesting solar energy and blazes a new trail in the field of fiber-shaped photovoltaicsclose

Flexible organo-metal halide perovskite solar cells on a Ti metal substrate

Organo-metal halide perovskite solar cells have received much attention in the field of photovoltaics in recent years. Herein, we report a flexible perovskite solar cell based on a metal substrate. It showed a power conversion efficiency of over 6% for the first time using a silver thin film as a semi-transparent top electrode on a Ti substrate.close7

Scalable Photovoltaic‐Electrochemical Cells for Hydrogen Production from Water ‐ Recent Advances

Hydrogen is regarded as a very important pillar for the future energy supply because it is readily available from water and can be used for environmentally friendly electricity generation. Hydrogen can be produced in various ways. Water splitting powered by renewable resources (e. g., solar, wind, etc.) can be an ideal way of hydrogen generation in the future since this approach can achieve true net-zero carbon dioxide emissions. This review article is aimed at giving an overview of the state-of-the-art hydrogen generation driven by photovoltaics (PVs) on a relatively large-scale (with PV area >50 cm2). The basic knowledge/principle of (PV-driven) water splitting is introduced in the beginning part. Then, different types of PV-driven water splitting devices and the recent advances in scalable PV-electrochemical water splitting devices are intensively reviewed in the middle part. Finally, cost predictions and challenges that need to be addressed are presented at the end of this article

Freeze-dried MoS2 sponge electrodes for enhanced electrochemical energy storage

In the present study, we have synthesized high surface area MoS2 sponge electrodes via a facile hydrothermal method followed by a freeze drying process. The performance of the MoS2 based symmetric capacitor showed a high specific capacitance value of around 128 F g(-1) at a scan rate of 2 mV s(-1), and also a single electrode showed a specific capacitance of 510 F g(-1), which is a remarkable value to be reported for a MoS2 based material in a symmetric device configuration. Also, a high energy density of around 6.15 Wh kg(-1) and a good cyclic stability over 4000 cycles are obtained for the symmetrical cell.clos

Efficient, durable and flexible perovskite photovoltaic devices with Ag-embedded ITO as the top electrode on a metal substrate

Efficient flexible perovskite solar cells based on a Ti substrate have been fabricated using indium tin oxide (ITO) as the top electrode. Furthermore, an ultra-thin Ag layer embedded between spiro-MeOTAD and ITO led to lower sheet resistance and a highly durable electrode compared with bare ITO. Inclusion of the Ag thin film has also provided enhanced electromagnetic fields on the surface of Ag for devices, which caused an increase of short circuit currentclose1

Fabrication of panchromatic dye-sensitized solar cells using pre-dye coated TiO2 nanoparticles by a simple dip coating technique

An appropriate method of pre-dye coating of TiO2 nanoparticles (NPs) and a facile approach of a dip coating technique have been adopted for the fabrication of panchromatic dye-sensitized solar cells (DSSC). A bi-layer photoanode consists of two distinct layers of TiO2 films, which were individually sensitized with N719 and N749 dyes and then coated on a TCO substrate in a sequenced manner. The spectral response of panchromatic DSSCs has been investigated using monochromatic incident photon to current conversion efficiency (IPCE) spectroscopy. The IPCE spectrum of panchromatic DSSC revealed the absorption characteristics of each single dye cell. The broader absorption spectra were obtained up to 850 nm of near IR region and the higher quantum efficiency than those of single cells were recorded. The higher value of IPCE is correlated with the higher short circuit current density value of panchromatic cell (J(sc) = 13.4 mA cm(-2)). The tandem cell showed an average open circuit voltage (V-oc = 0.79 V) of the single dye cells with an overall conversion efficiency of 7.1%. Moreover, the present approach does not require any high temperature sintering process; therefore it could be suitable for the fabrication of flexible panchromatic DSSCs.close3