A general approach to realizing perovskite nanocrystals with insulating metal sulfate shells

Solid-state synthesis of cesium manganese halide nanocrystals in glass with bright and broad red emission for white LEDs

Recently, lead halide perovskite nanocrystals (NCs) have attracted extensive attention due to their unique optical properties. However, the toxicity of lead and the instability to moisture obstruct their further commercial development. Herein, a series of lead-free CsMnX₃ (X = Cl, Br, and I) NCs embedded in glasses were synthesized by a high temperature solid-state chemistry method. These NCs embedded in glass can remain stable after soaking in water for 90 days. It is found that increasing the amount of cesium carbonate in the synthesis process can not only prevent the oxidation of Mn²⁺ to Mn³⁺ and promote the transparency of glass in the 450-700 nm region, but also significantly increase its photoluminescence quantum yield (PLQY) from 2.9% to 65.1%, which is the highest reported value of the red CsMnX₃ NCs so far. Using CsMnBr₃ NCs with a red emission peak at 649 nm and full-width-at-half-maximum (FWHM) of 130 nm as the red light source, a white light-emitting diode (LED) device with International Commission on illumination (CIE) coordinates of (0.33, 0.36) and a color rendering index (CRI) of 94 was obtained. These findings, together with future research, are likely to yield stable and bright lead-free NCs for the next generation of solid-state lighting.

Encapsulation of lead halide perovskite nanocrystals (NCs) at the single-particle level: strategies and properties

Lead halide perovskite NCs (APbX₃, A = formamidinium (FA), methylammonium (MA) or Cs; X = Cl, Br, I or their mixture) have attracted unprecedented attention due to their excellent photophysical properties and wide application prospects. However, the inherent ionic structure of APbX₃ NCs makes them very sensitive to external conditions such as water and oxygen, resulting in poor stability. As a feasible strategy, encapsulation is considered to be effective in improving the stability. In this minireview, we focus on single-particle-level coating, which not only can improve the stability but also maintain the nano effect of the original NCs. This review summarizes the fundamental information on APbX₃ NCs and the necessity of single-particle-level coating. Subsequently, a variety of heterostructures at the single-particle level are introduced in detail. Then, their applications are summarized. Moreover, we discuss the challenges and prospects of the single-particle-level heterostructures based on APbX₃ NCs.

Quantum Dot Photocatalysts for Organic Transformations

Quantum dots (QDs) with tunable photo-optical properties and colloidal nature are ideal for a wide range of photocatalytic reactions. In particular, QD photocatalysts for organic transformations can provide new and effective synthetic routes to high value-added molecules under mild conditions. In this Perspective, we discuss the advances of employing QDs for visible-light-driven organic transformations categorized into net reductive reactions, net oxidative reactions, and redox neutral reactions. We then provide our outlook for potential future directions in the field: nanostructure engineering to improve charge separation efficiencies, ligand shell engineering to optimize overall catalyst performance, in situ comprehensive studies to delineate underlying reaction mechanisms, and laboratory automation with the assistance of modern computing techniques to revolutionize the reaction optimization process.