Synthesis and dimensional control of CsPbBr3 perovskite nanocrystals using phosphorous based ligands

Nanocrystals of the inorganic perovskite, CsPbBr3, display outstanding photo-physical properties, making them ideal for next generation optical devices. However, the typical combination of oleic acid and oleylamine ligands employed in their synthesis is easily displaced, leading to poor stability that can hinder their applicability. In this work, we look toward the replacement of the oleic acid and amine with phosphorous based ligands. We synthesize CsPbBr3 nanocrystals using an oleylamine/alkylphosphonic acid combination with near perfect monodispersity with the ability to tune the bandgap by varying the alkyl chain length. We further investigate the replacement of the oleylamine giving a ligand combination of alkylphosphonic acid/trioctylphosphine oxide for perovskite nanocrystal nucleation and growth. This combination is typical for the widely studied metal chalcogenide synthesis and in our study with CsPbBr3 yields a pure phase perovskite

Self-standing 3D core-shell nanohybrids based on amorphous Co-Fe-Bi nanosheets grafted on NiCo2O4 nanowires for efficient and durable water oxidation

Here, a three-dimensional (3D) core–shell nanohybrid based on few-layer amorphous Co–Fe–Bi nanosheets directly grown on crystalline NiCo2O4 nanowires supported on the Ni foam (Co–Fe–Bi/NiCo2O4/NF) are facilely fabricated as highly efficient and durable electrocatalysts for water oxidation. This self-standing 3D core–shell nanohybrid design with unique materials chemistry and excellent interface engineering enhances the mass transport and stimulates the production of active sites during the oxygen evolution reaction. Serving as the anode catalysts, the resulting self-standing Co–Fe–Bi/NiCo2O4/NF nanohybrid electrocatalysts show a better electrocatalytic activity with an overpotential of 227 mV at 10 mA/cm2, a Tafel slope of 45 mV dec–1, excellent durability over 40 h, and the ability to deliver a current density of 200 mA/cm2 at an overpotential of ∼410 mV in an alkaline medium. Thus, the excellent electrocatalytic performance of the Co–Fe–Bi/NiCo2O4/NF nanohybrid demonstrates the importance of design and development of core–shell nanohybrids for large-scale practical applications in a multitude of energy conversion devices

Colloidal Wurtzite Cu₂SnS₃ (CTS) Nanocrystals and Their Applications in Solar Cells

In the development of low-cost, efficient, and environmentally friendly thin-film solar cells (TFSCs), the search continues for a suitable inorganic colloidal nanocrystal (NC) ink that can be easily used in scalable coating/printing processes. In this work, we first report on the colloidal synthesis of pure wurtzite (WZ) Cu₂SnS₃ (CTS) NCs using a polyol-mediated hot injection route, which is a nontoxic synthesis method. The synthesized material exhibits a random distribution of CTS nanoflakes with an average lateral dimension of ∼94 ± 15 nm. We also demonstrate that CTS NC ink can be used to fabricate low-cost and environmentally friendly TFSCs through an ethanol-based ink process. The annealing of as-deposited CTS films was performed under different S vapor pressures in a graphite box (volume; 12.3 cm³), at 580 °C for 10 min using a rapid thermal annealing (RTA) process. A comparative study on the performances of the solar cells with CTS absorber layers annealed under different S vapor pressures was conducted. The device derived from the CTS absorber annealed at 350 Torr of S vapor pressure showed the best conversion efficiency 2.77%, which is the first notable efficiency for an CTS NCs ink-based TFSC. In addition, CTS TFSC’s performance degraded only slightly after 50 days in air atmosphere and under damp heating at 90 °C for 50 h, indicating their good stability. These results confirm that WZ CTS NCs may be very attractive and interesting light-absorbing materials for fabricating efficient solar-harvesting devices