Efficient Blocking Layer Research Articles

Covalent netting restrains dissolution enabling stable high-loading and high-rate iron difluoride cathodes.

Metal fluoride conversion cathodes are promising for the production of cheap, sustainable, and high-energy lithium-ion batteries. Yet, such systems are plagued by active material dissolution that causes capacity fade and hinders commercialization. Here, a covalent netting strategy is proposed to overcome this hurdle. In a proof-of-concept design, polydopamine derived carbon-mediated covalent binding inhibited the dissolution, while the pyrolyzed bacterial cellulose netting structure furnished fast electronic and ionic transport pathways. We demonstrate high-capacity, high-rate and long-lasting stability attained at practical loading levels. Our investigations suggest that the covalent netting-enabled formation of a robust and efficient blocking layer, highly competent in suppressing the leaching, is key for a stable performance. The successful stabilization of metal difluorides in the absence of electrolyte engineering opens an avenue for their practical deployment in future higher-level but lower-cost batteries, and provides a solution to similar challenges encountered by other dissolving energy electrode materials.

Performance improvement of dye-sensitized solar cell by introducing Sm3 +/Y3 + co-doped TiO2 film as an efficient blocking layer

Luminescence mediums: samarium ion and yttrium ion, were introduced to expand the photo-response region of TiO2 by means of the down-conversion effect to convert ultraviolet light into visible light, offering a unique method to enhance the photovoltaic performance of dye-sensitized solar cells (DSSCs). Their crystal structures, optical properties as well as photovoltaic performance were investigated systematically. The result indicates that the DSSCs doped with a total molar ratio of 4mol% of Sm3+ and Y3+ show an overall power conversion efficiency of 4.09%, which is equivalent to improvements of 17.52% and 16.2% as compared to the no blocking layer DSSCs and pure TiO2 blocking layer DSSCs respectively. The improvement in conversion efficiency is attributed to the dual effects including down-conversion of ultraviolet light and reduction of electron-hole recombination rate.

Blocking layers for nanocomposite photoanodes in dye sensitized solar cells: Comparison of atomic layer deposition and TiCl4 treatment

Charge recombination at the electrode/electrolyte interface can be prevented by efficient blocking layers. Here, TiO2 blocking layers have been deposited using atomic layer deposition (ALD) and TiCl4 treatment. The number of TiO2 ALD cycles was optimized for I−/I3− and Fc/Fc+ electrolytes. The optimized TiO2 ALD films' performance was compared with the TiCl4 treated films. TiCl4 treated films performed better than the ALD deposited films, attributed to reduction of the defects, which act as active sites of recombination.

Multifunctional alumina/titania hybrid blocking layer modified nanocrystalline titania films as efficient photoanodes in dye sensitized solar cells

A facile way of fabricating efficient blocking layer on mesoporous TiO2 film of dye-sensitized solar cells (DSSCs) is demonstrated here for the first time. Al2O3 and TiO2 are combined together to form a blocking layer. A simple spin coating technique is employed which is a versatile and low-cost method over the atomic layer deposition (ALD) technique. Multifunctional alumina/titania (Al2O3/TiO2) hybrid overlayer is prepared on traditional TiO2 nanocrystalline thin film surface, through sequential deposition of AlCl3·6H2O and TiCl4 precursor solutions followed by sintering at 500 °C for 30 min. Al2O3 effectively plays its role in retarding interfacial recombination of electrons and improving open circuit potential (Voc), while the tiny TiO2 clusters synthesized from TiCl4 treatment act as electron transporting channels to facilitate electron diffusion which leads to enhanced photocurrent (Jsc). Compared to the device without blocking layer, the DSSCs assembled with Al2O3/TiO2 hybrid blocking layer showed improvement in Jsc (from 13.09 mA/cm2 to 16.90 mA/cm2) as well as in Voc (from 0.72 V to 0.73 V) resulting a much better conversion efficiency of 8.60%.

A novel TiO2 nanoparticles/nanowires composite core with ZrO2 nanoparticles shell coating photoanode for high-performance dye-sensitized solar cell based on different electrolytes

The novel TiO2 nanopartilces/nanowires (TNPWs) composite with ZrO2 nanoparticles (ZNPs) shell-coated photoanodes were prepared to fabricate high-performance dye-sensitized solar cell (DSSC) based on different types of electrolytes. Hafnium oxide (HfO2) is a new and efficient blocking layer material applied over the TNPWs-ZNPs core-shell photoanode film. TiO2 nanoparticles (TNPs) and TiO2 nanowires (TNWs) were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). DSSCs were fabricated using the novel photoanodes with an organic sensitizer D149 dye and different types of electrolytes namely liquid electrolyte, ionic liquid electrolyte, solid-state electrolyte, and quasi-solid-state electrolyte. The DSSC-4 made through the novel core-shell photoanode using quasi-solid-state electrolyte showed better photocurrent efficiency (PCE) as compared to the other DSSCs. It has such photocurrent-voltage characteristics: short circuit photocurrent (Jsc) = 19 mA/cm2, the open circuit voltage (Voc) = 650 mV, fill factor (FF) = 65 %, and PCE (η) = 8.03 %. The improved performance of DSSC-4 is ascribed to the core-shell with blocking layer photoanode could increased electron transport and suppressed recombination of charge carriers at the TNPWs-ZNPs/dye/electrolyte interface.

Highly efficient dye-sensitized solar cells based on HfO2 modified TiO2 electrodes

In this article, we describe the use of hafnium oxide (HfO2) as a new and efficient blocking layer material to modify TiO2 electrodes in dye sensitized solar cells. Different thicknesses of HfO2 over-layers were prepared by simple dip coating from two different precursors and their effects on the performance of DSSCs were studied. The HfO2 modification remarkably increases dye adsorption, resulting from the fact that the surface of HfO2 is more basic than that of TiO2. Furthermore, the HfO2 coating demonstrated increased diffusion coefficient (De) and lifetime (τe) of the photoelectrons, indicating the improved retardation of the back electron transfer, which increases short-circuit current (Jsc) and open-circuit voltage (Voc). Thereby, the photo conversion efficiency (η) of the solar cell was greatly improved from 5.67 to 9.59% (an improvement of 69.02%) as the HfO2 layer was coated over TiO2 films.

Effects of Cr2O3 modification on the performance of SnO2 electrodes in DSSCs

In this paper, we demonstrate that Cr(2)O(3), a visible absorbing insulator, can be used as an efficient blocking layer material for the anode of dye-sensitized solar cells (DSSCs). We prepared SnO(2) electrodes surface-modified with Cr(2)O(3) with various Cr/Sn ratios and studied the effect of the modification on the performance of DSSCs. DSSCs with Cr/Sn ratios 0.02, 0.05, and 0.10 showed increased overall photon-to-electricity conversion efficiency from that of pure SnO(2). Especially, the DSSC with the Cr/Sn ratio 0.02 showed a remarkably large increase by 55%. The electrode materials were analyzed by powder X-ray diffraction, transmission electron microscopy, N(2) adsorption studies, and UV-Vis diffuse reflectance spectroscopy. The Cr-containing species appears to be Cr(2)O(3) nanoparticles, spread evenly on the SnO(2) nanoparticles and filling the gap space between SnO(2) particles. The electrochemical properties of the electrodes were characterized by Mott-Schottky plots and electrochemical impedance spectroscopy. As the Cr-content increases, the flat-band potential is negatively shifted. The impedance spectroscopy data show that Cr/Sn = 0.02 and 0.05 samples have lower charge transport resistance at the electrode, which can be explained by the rise of the conduction level due to the charge transfer from the more basic Cr(2)O(3) nanoparticles to SnO(2) nanoparticles. These observations corroborate with the trends of the short-circuit current and the open-circuit voltage of the DSSCs.

Layer-by-layer TiO 2 films as efficient blocking layers in dye-sensitized solar cells

Charge recombination at the conductor substrate/electrolyte interface has been prevented by using efficient blocking layers of TiO 2 compact films in dye-sensitized solar cell photoanodes. Compact blocking layers have been deposited before the mesoporous TiO 2 film by the layer-by-layer technique using titania nanoparticles as cations and sodium sulfonated polystyrene, PSS, as a polyanion. The TiO 2/PSS blocking layer in a DSC prevents the physical contact of FTO and the electrolyte and leads to a 28% increase in the cell's overall conversion efficiency, from 5.7% to 7.3%.

Quantum dot‐based protein micro‐ and nanoarrays for detection of prostate cancer biomarkers

In this article, we demonstrate the fabrication and detection of cancer protein biochips consisting of micro- and nanoarrays whereby pegylated quantum dots (QDs) conjugated to antibodies (Abs) of prostate specific antigens (PSA) were used for the detection of clinical biomarkers such as PSA. BSA which acts as an efficient blocking layer in microarrays, tends to show an interaction with QDs. In view of this fact, we investigated two series of samples which were fabricated in the presence and absence of BSA blocking layer. Variation in the incubation time required for the antigen-antibody interaction to take place, different proteins as controls and the effect of bare QDs on these microarrays, were the three main parameters which were studied in these two series. Samples fabricated in the absence of BSA blocking layer exhibited an extremely high specificity in the detection of cancer proteins and were also marked by negligible nonspecific binding effects of QDs, in stark contrast to the samples fabricated using BSA as a blocking layer. Fabrication of nanoarrays of QD-conjugated PSA Abs having a spot size of nearly 900 nm has also been demonstrated. Thus, we show the potential offered by QDs in in vitro analysis of cancer biomarker imaging.

High Temperature Sputtered TiO2 Film as an Efficient Blocking Layer for the Dye-sensitized Solar Cells

We investigated the carrier leakage blocking effect of the magnetron sputtered TiO2 film insertion between transparent anodic electrode and porous TiO2 film in the dye-sensitized solar cell (DSC), as a consequence of preventing the ionic short-circuiting of the electrolyte to the anodic electrode through porous TiO2 film. The optimization of the deposition condition of the high temperature TiO2 sputtering for the carrier leakage blocking is reported.