Search

TiO2 nanocubes were synthesized via hydrolysis condensation of titanium tetra-isopropoxide (TTIP) in aqueous media, followed by hydrothermal treatment with ammonium salts. Various ammonium salts with different alkyl chain such as ammonium hydroxide (NH4OH), tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH) and tetrabutylammonium hydroxide (TBAH) were investigated. The crystalline phase, shape, and morphology of TiO2 nanocubes were studied by XRD, TEM, and SEM analysis. These TiO2 nanocubes were pure anatase phase and tended to assemble with well-ordered and close-packed domains. Both alkyl chain length of ammonium salts and hydrothermal duration affected the TiO2 nanocube formation process. The ammonium salts with longer alkyl chain formed TiO2 nanocubes in shorter hydrothermal time and offered the smallest particle size. The above TiO2 nanocubes were applied as photoanode materials in N719 anchored dye-sensitized solar cells and one of the cells exhibited the maximum power conversion efficiency of 7.85%.

Three tertiary amine dyes (TD01, TD02, and TD03) have been designed and synthesized for the dye sensitized solar cell (DSSC) application. These new dyes TD01, TD02, and TD03 carry different number (one, two, and three, respectively) of donor-π-acceptor units, which are connected together with a central bridgehead nitrogen through oxyethyl linkers. After fabricating the solar cells using these sensitizers and investigating their photovoltaic performances, it was found that the DSSC based on TD03 sensitizer exhibited the best power conversion efficiency of 5.91%. The higher performance of TD03 compared to TD01 and TD02 sensitizers is attributed to its superior short-circuit current density and high open-circuit voltage resulted from the presence of tertiary anchoring and oxyethyl moieties, respectively.

The surface modification of the TiO2 photoelectrode film is one of the promising ways to improve the photovoltaic performance of dye-sensitized solar cell (DSSC). In this work for the acid treatment of TiO2 powder, fluorine containing compounds such as trifluoroacetic acid was carried out to enhance the properties of photoanode. In order to investigate the effect of trifluoroacetyl group, the TiO2 nanopowders were also treated with different acids such as acetic acid, nitric acid, hydrochloric acid, and sulfuric acid and their properties were compared. The TiO2 powders treated with both acetic acid and TFA have possessed smooth surface morphologies as well as enhanced particle dispersions with reduced particle sizes. Photoelectrodes prepared for these two kinds of TiO2 powders accommodated high amounts of dye loading and exhibited excellent light transmittance (wavelength region of 400–600 nm). Electrochemical impedance spectroscopy analysis showed the smallest radius of the semicircle which indicates the enhanced rate of electron transport for the cell based photoelectrode with trifluoroacetic acid treated TiO2 powder. The solar cell from the untreated TiO2 film showed the power conversion efficiency of 8.86% and the highest efficiency of 9.51% was achieved by the cell fabricated from trifluoroacetic acid treated TiO2 film.

The controlled morphological TiO 2 particles have gained great importance in a wide variety of applications due to their promising physico-chemical properties. In this study, TiO 2 microstructures with various shapes to utilize as scattering layer in dye-sensitized solar cell (DSSC) applications were successfully synthesized via different hydrothermal conditions. The effects of the versatile preparation parameters including the amount of titania precursor and surfactant, the addition of ethanol/water, and the hydrothermal process temperature and time on the TiO 2 morphology were investigated. The structural and morphological analysis clearly shown that the preparation conditions played crucial roles in the morphology, particle size, and crystalline phase of the TiO 2 microparticles. Different kinds of shapes such as rice- (∼1.10 μm (l) and ∼0.41 μm (w)), star- (∼3.60 μm) and flower-like (3.75 μm) TiO 2 morphological structures were obtained. The morphology and size of the TiO 2 particles were mainly governed by the concentrations of titanium tetraisopropoxide (TTIP) precursor, amounts of tetramethylammonium hydroxide (TMAH) surfactant and hydrothermal temperatures and durations. The as-prepared rice-shaped TiO 2 was composed of mixed anatase and brookite binary phases, whereas the star- and flower-shaped TiO 2 microstructures were consisted of ternary anatase, rutile, and brookite crystalline TiO 2 phases. The three different rice-, star-, and flower-shaped TiO 2 microstructures were employed as scattering layers for photoanodes in DSSCs. Among them, the star-like TiO 2 photoanode based DSSC exhibited the highest power conversion efficiency of 9.56%, which was also better than those of the devices fabricated without scattering layer (a-TiO 2 , 8.38%) and with commercial P25 as scattering layer (a-TiO 2 /P25-TiO 2 , 8.52%) at the same film thickness of ∼14 μm.

A unique quaternary iodide salt of thieno-imidazole, AI110, is designed, prepared and tested on an inverted (p-i-n) architecture perovskite solar cell (PSC) as a dopant-free hole transport material (HTM). The opto-electronic and power conversion properties of this novel aryl salt HTM are well characterized. The inverted PSC based on AI110 without any dopants and additional interlayers using the simplest device structure affords the best efficiency of 14.90%, which is much higher than those of the most widely used HTMs, Spiro-OMeTAD (11.84%) and PEDOT:PSS (12.55%). The superior performance of the aryl salt AI110 HTM is due to its significant capabilities of film formation, charge extraction, and hole mobilities which result in reducing current loses and charge recombination and thus increasing power conversion.

TiO2 nanocubes were synthesized via hydrolysis condensation of titanium tetra-isopropoxide (TTIP) in aqueous media, followed by hydrothermal treatment with ammonium salts. Various ammonium salts with different alkyl chain such as ammonium hydroxide (NH4OH), tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH) and tetrabutylammonium hydroxide (TBAH) were investigated. The crystalline phase, shape, and morphology of TiO2 nanocubes were studied by XRD, TEM, and SEM analysis. These TiO2 nanocubes were pure anatase phase and tended to assemble with well-ordered and close-packed domains. Both alkyl chain length of ammonium salts and hydrothermal duration affected the TiO2 nanocube formation process. The ammonium salts with longer alkyl chain formed TiO2 nanocubes in shorter hydrothermal time and offered the smallest particle size. The above TiO2 nanocubes were applied as photoanode materials in N719 anchored dye-sensitized solar cells and one of the cells exhibited the maximum power conversion efficiency of 7.85%.