Environmentally-friendly synthesis of highly luminescent cesium lead halide perovskite nanocrystals using Sn-based halide precursors

Deep-Blue Perovskite Light-Emitting Diodes Realized by a Dynamic Interfacial Ion Exchange

The external quantum efficiency (EQE) of the sky-blue perovskite light-emitting diodes (PeLEDs) has reached 18.65%. However, the EQE of the deep-blue PeLEDs is still inferior to that of sky-blue PeLEDs, which restricts the PeLED application in displays. Herein, a novel dynamic interfacial ion-exchange technique is developed to obtain deep-blue PeLEDs. By spin-coating quaternary ammonium chloride on top of a quasi-2D green perovskite film, a 68 nm spectral transition from green light emission at 513 nm to deep-blue light emission at 445 nm has been successfully realized. To the best of our knowledge, it is the largest spectrum transition ever achieved. By further introducing tricyclohexylphosphine oxide into the perovskite precursor solution to passivate defects, high-quality deep-blue PeLEDs have been fabricated with color coordinates at (0.13, 0.06). The maximum EQE reaches 1.8%, and the peak luminance reaches 847 cd/m².

Metal Halide Perovskite Nanocrystals: Synthesis, Post-Synthesis Modifications, and Their Optical Properties

Metal halide perovskites represent a flourishing area of research, which is driven by both their potential application in photovoltaics and optoelectronics and by the fundamental science behind their unique optoelectronic properties. The emergence of new colloidal methods for the synthesis of halide perovskite nanocrystals, as well as the interesting characteristics of this new type of material, has attracted the attention of many researchers. This review aims to provide an up-to-date survey of this fast-moving field and will mainly focus on the different colloidal synthesis approaches that have been developed. We will examine the chemistry and the capability of different colloidal synthetic routes with regard to controlling the shape, size, and optical properties of the resulting nanocrystals. We will also provide an up-to-date overview of their postsynthesis transformations, and summarize the various solution processes that are aimed at fabricating halide perovskite-based nanocomposites. Furthermore, we will review the fundamental optical properties of halide perovskite nanocrystals by focusing on their linear optical properties, on the effects of quantum confinement, and on the current knowledge of their exciton binding energies. We will also discuss the emergence of nonlinear phenomena such as multiphoton absorption, biexcitons, and carrier multiplication. Finally, we will discuss open questions and possible future directions.

Synthesis and characterization of Mn-doped CsPb(Cl/Br)3 perovskite nanocrystals with controllable dual-color emission

Colloidal Mn-doped CsPb(Cl/Br)₃ NCs were synthesized at different MnCl₂-to-PbBr₂ molar feed ratios or reaction temperatures to tune their color emission.