We report a colloidal synthesis approach to CsPbBr3 nanoplatelets. The nucleation and growth of the platelets, which takes place at room temperature, is triggered by the injection of acetone in a mixture of precursors that would remain unreactive otherwise. The low growth temperature enables the control of the plate thickness, which can be precisely tuned from 3 to 5 monolayers. The strong two-dimensional confinement of the carriers at such small vertical sizes is responsible for the narrow PL, the strong excitonic absorption and the blue shift of the optical band gap of more than 0.47 eV compared to that of bulk CsPbBr3. We also show that the composition of the platelets can be varied all the way to CsPbCl3 or to CsPbI3 by anion exchange, with preservation of size and shape of the starting particles. The blue fluorescent CsPbCl3 nanoplatelets represent a new member of the scarcely populated group of blue emitting colloidal nanocrystals. The exciton dynamics were found to be independent of the extent of 2D confinement in these platelets, and this was supported by band structure calculations.

An increasing number of studies have recently reported the rapid degradation of hybrid and all-inorganic lead halide perovskite nanocrystals under electron beam irradiation in the transmission electron microscope, with the formation of nanometer size, high contrast particles. The nature of these nanoparticles and the involved transformations in the perovskite nanocrystals are still a matter of debate. Herein, we have studied the effects of high energy (80/200 keV) electron irradiation on colloidal cesium lead bromide (CsPbBr₃) nanocrystals with different shapes and sizes, especially 3 nm thick nanosheets, a morphology that facilitated the analysis of the various ongoing processes. Our results show that the CsPbBr₃ nanocrystals undergo a radiolysis process, with electron stimulated desorption of a fraction of bromine atoms and the reduction of a fraction of Pb²⁺ ions to Pb⁰. Subsequently Pb⁰ atoms diffuse and aggregate, giving rise to the high contrast particles, as previously reported by various groups. The diffusion is facilitated by both high temperature and electron beam irradiation. The early stage Pb nanoparticles are epitaxially bound to the parent CsPbBr₃ lattice, and evolve into nonepitaxially bound Pb crystals upon further irradiation, leading to local amorphization and consequent dismantling of the CsPbBr₃ lattice. The comparison among CsPbBr₃ nanocrystals with various shapes and sizes evidences that the damage is particularly pronounced at the corners and edges of the surface, due to a lower diffusion barrier for Pb⁰ on the surface than inside the crystal and the presence of a larger fraction of under-coordinated atoms.

Well-known since the 18th century and widely used in painting and later in photography, hexacyanoferrate, or “Prussian blue”, is currently getting its “second life” as a promising material in several of the most advanced fields of the present technological sectors. This is mostly due to the rapid development of the energy storage market, which requires advanced, reliable, but also cost-effective materials for large-scale applications in load-levelling of renewable energy power sources. Non-Li technologies are considered as one of the most fertile R&D directions in this field, and Prussian blue demonstrates extremely promising characteristics for this kind of application. The unique features of this material are due to peculiarities of its atomic structure and ionic and electronic properties. In this article we review and discuss current research efforts in this field employing different hexacyanoferrate-based compounds as potential electrochemical storage and electrochromic devices. After a brief review of its history, we analyze the peculiarities of the atomic structure of these types of systems. We further summarize and analyze the most important and interesting experimental electrochemical data in this field, linking the particular atomic structure of the studied compounds with their observed electrochemical behaviour. This provides us with a snapshot of the current experimental state in this field and allows us to make certain predictions for its future development.

Recently, intensive efforts are dedicated to convert and store the solar energy in a single device. Herein, dye-synthesized solar cell technology is combined with lithium-ion materials to investigate light-assisted battery charging. In particular we report the direct photo-oxidation of lithium iron phosphate nanocrystals in the presence of a dye as a hybrid photo-cathode in a two-electrode system, with lithium metal as anode and lithium hexafluorophosphate in carbonate-based electrolyte; a configuration corresponding to lithium ion battery charging. Dye-sensitization generates electron–hole pairs with the holes aiding the delithiation of lithium iron phosphate at the cathode and electrons utilized in the formation of a solid electrolyte interface at the anode via oxygen reduction. Lithium iron phosphate acts effectively as a reversible redox agent for the regeneration of the dye. Our findings provide possibilities in advancing the design principles for photo-rechargeable lithium ion batteries.