Tham Adhikari

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.

Quality and Durability of Warm Rubberized Asphalt Cement in Ontario, Canada

This paper documents and discusses an investigation of performance-based testing of asphalt cement (AC), AC modified with warm-mix technology additives (warm AC), rubberized asphalt cement (RAC), and warm RAC. A number of control, warm, and RAC binders from Ontario, Canada, construction contracts were investigated for their compliance with conventional Superpave® as well as additional specification criteria. It was found that all samples passed the Superpave requirements but only one satisfied the additional Ontario criteria. One warm AC and two field-blended RAC samples showed high levels of physical hardening, which can lead to early cracking. The warm AC lost 8°C when stored isothermally for 3 days at low temperatures according to Ontarios extended bending beam rheometer protocol (LS-308). The two RAC samples lost 10°C and 12°C following the same conditioning. Many of the investigated samples showed deficient strain tolerance as measured in Ontarios double-edge-notched tension test (LS-299). In an effort to formulate warm RAC with improved properties, a number of compositions were prepared with soft Cold Lake AC and a small quantity of naphthenic oil. These binders showed little chemical and physical hardening and reasonable critical crack tip opening displacements. Strain tolerance was much improved by coblending with a high vinyl-type styrene–butadiene–styrene polymer and a small amount of sulfur. The Ministry of Transportation of Ontario is interested in using the developed formulations in future pavement trials with expected improvements in pavement performance.

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.