Size Dependent Ternary Halide Solid Solutions in Perovskite Nanocrystals

TL;DR

This study explores how nanocrystal size influences the solubility and stability of ternary halide perovskite solid solutions, revealing size-dependent miscibility and defect suppression through extensive synthesis and modeling.

Contribution

It provides the first comprehensive analysis of size-dependent solubility limits in halide perovskite nanocrystals using high throughput experiments and theoretical models.

Findings

Smaller nanocrystals stabilize wider ternary halide compositions.

Extended solubility boundaries compared to bulk materials.

Suppression of halide segregation and stacking faults in small nanocrystals.

Abstract

Crystalline solid solutions incorporate guest atoms by substituting host lattice sites up to a solubility limit dictated by solute host similarity. Solid solutions enable tuning various material properties, such as the optoelectronic behavior of halide perovskites. In bulk, incompatibility of Cl:I halide mixtures restricts exploration throughout the ternary halide Cl:Br:I compositional range. However, solubility is extended in nanocrystals which better accommodate a wider range of ions within their lattice. Through high throughput synthesis and spectroscopic characterization of over 3000 samples, along with density functional theory and cluster expansion models, we determine the solubility boundaries of ternary halide perovskite nanocrystals and demonstrate their extended size dependent miscibility. Smaller nanocrystals, with sufficient Br content, stabilize the Cl:Br:I solid solutions, suppress planar stacking fault defects and prevent halide segregation.