Javeed Akhtar

Bis(selenobenzoato)dibutyltin(IV) as a single source precursor for the synthesis of SnSe nanosheets and their photo-electrochemical study for water splitting

A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth were found to be significantly altered by changes in the deposition temperature. Oleylamine capped nanosheets and the as-deposited thin films by AACVD were characterized by powder X-ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, and all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectrochemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), by switching the applied potential.

Cesium Lead Halide Perovskite Nanostructures: Tunable Morphology and Halide Composition

Inorganic halide perovskite (CsPbX3 ) nanostructures have gained considerable interest in recent years owing to their enhanced stability and optoelectronic applications. Recent developments in the synthesis of nanostructures are reviewed. The impact of the precursor and ligand nature, temperature and growth time on the morphology and shape tuning of CsPbX3 nanostructures is described in relation to their optical properties. The presynthetic and postsynthetic anion exchange strategies to retain pre-existing crystal phase and shape are discussed in this minireview.

Fabrication of planar heterojunction CsPbBr2I perovskite solar cells using ZnO as an electron transport layer and improved solar energy conversion efficiency

Inorganic lead halide perovskite solar cells with mixed halides have achieved reasonable power conversion efficiency with the advantage of enhanced stability. In this work, we report the fabrication of an all-inorganic cesium lead bromoiodide based planar perovskite solar cell with a ZnO electron transport layer. The method described herein includes the use of one step spin coating solution processing using a solvent mixture (DMF + DMSO) to avoid the solubility issues of CsPbBr2I perovskite in DMF. The substrate temperature during spin coating was found to be a critical parameter to generate the required crystalline morphology of the perovskite thin films. Post-annealing of the as-deposited perovskite film at 275 °C led to the formation of the cubic phase of CsPbBr2I with an optical band gap of 2.06 eV. Interestingly, cubic shaped CsPbBr2I morphology was obtained via single-step spin-coating processing that otherwise required two-step solution deposition of the hybrid perovskite. The best performing devices achieved 4.8% power conversion efficiency with minimal hysteresis and enhanced thermal and photo-stability. Owing to enhanced thermal and photo-stability, inorganic perovskites appear as viable alternatives to hybrid organic–inorganic perovskites for solar cell applications.

Organometal Lead Halide Perovskite

Abstract The chemistry of organometal lead halides has been established since early 20th century. In 1970, for the first time, Weber has reported the synthesis and physical properties of CH3NH3PbX3 (X=Cl, Br, I) organometal lead halide perovskite. Today, the organometal lead halide perovskites have been emerged as the promising candidate as light harvesters in the solar cell with the first solar cell reported in 2009.

Broadband emission in a new lead free all-inorganic 3D CsZnCl2I perovskite

This contribution reports the deposition of new zinc based lead free all inorganic 3D CsZnCl2I perovskite thin films using aerosol assisted chemical vapour deposition (AACVD) at 100 °C. Room tempertaure optical measurements performed on the as-deposited thin films showed two absorption peaks. Upon 325 nm excitation, the CsZnCl2I perovskite thin film showed broad band white light emission having two peaks, which cover the entire visible range of the spectrum. This is the first example of white light emission from 3D all-inorganic lead free mixed halide CsZnCl2I perovskites.

Low-temperature solution-phase route to sub-10 nm titanium oxide nanocrystals having super-enhanced photoreactivity

High-purity anatase nanocrystals were prepared by using a low-temperature surfactant-assisted solution-phase method. Titanium tetra-isopropoxide (TTIP) was used as a precursor, polyethylene glycol (PEG) as a surfactant, and isopropyl alcohol (IPA) and water as solvent. An isopropanolic solution of TTIP and PEG was mixed with an aqueous acidic solution at about 60 °C to yield a whitish sol that, after being baked at 60 °C for 6 hours, was transformed into phase-pure anatase crystals with dimensions of about 8 nm. By varying the mass of the PEG surfactant from 0.5 to 2 g, the particle dimensions could be controlled to be between 8 and 11 nm. Thermogravimetric analysis in combination with transmission electron microscopy (TEM), XRD, and Raman, Ultraviolet-visible (UV-vis) and infrared spectroscopies showed the nanocrystals with dimensions of 8–11 nm to be composed of an anatase lattice with hydroxyl bound to the surface. These nanocrystals showed much improved efficiency for photodegradation of methylene blue as compared with the commercial Degussa P25, due to the extraordinarily increased surface area. These findings may inspire the engineering of highly active subnanometer-sized nanocrystals for energy- and environment-related applications.