Growth of Metal Halide Perovskite, from Nanocrystal to Micron-Scale Crystal: A Review

Abstract

Metal halide perovskite both in the form of nanocrystal and thin films recently emerged as the most promising semiconductor material covering a huge range of potential applications from display technologies to photovoltaics. Colloidal inorganic and organic-inorganic hybrid metal halide perovskite nanocrystals (NCs) have received tremendous attention due to their high photoluminescence quantum yields, while large grain perovskite films possess fewer defects, and a long diffusion length providing high-power conversion efficiency in planar devices. In this review, we summarize the different synthesis routes of metal halide perovskite nanocrystals and the recent methodologies to fabricate high-quality micron scale crystals in the form of films for planar photovoltaics. For the colloidal synthesis of halide perovskite NCs, two methods including ligand-assisted reprecipitation and hot injection are mainly applied, and the doping of metal ions in NCs as well as anion exchange reactions are widely used to tune their optical properties. In addition, recent growth methods and underlying mechanism for high-quality micron size crystals are also investigated, which are summarized as solution-process methods (including the anti-solvent method, solvent vapor annealing technology, Ostwald ripening, additive engineering and geometrically-confined lateral crystal growth) and the physical method (vapor-assisted crystal growth).

Halide Perovskite Nanocrystals for Next‐Generation Optoelectronics

“…The facile synthesis of Pb‐based hybrid (e.g., MAPbX 3 , FAPbX 3 ) or fully inorganic (e.g., CsPbX 3 ) nanometer‐sized perovskite crystals, combined with their excellent optoelectronic properties, has motivated huge research efforts on this technology in the latest years . In this section, we will briefly introduce the mainstream synthesis methods, including the presynthetic (colloidal synthesis) and postsynthetic chemical transformations, together with their related challenges.…”

“…The easy formation of PNCs even at room temperature, as a consequence of their highly ionic nature, enables several possible approaches for the direct synthesis of hybrid or inorganic colloidal PNCs, among which the most common methods are ligand‐assisted reprecipitation (LARP) and hot injection …”

“…f) Schematic diagram of hot injection system. Reproduced with permission . Copyright 2018, Multidisciplinary Digital Publishing Institute.…”

“…The hot injection method does not involve polar solvents but requires a high synthesis temperature (up to 250 °C) and inorganic molecular precursors that are stable at that temperature. Typically, a cation (in the form of Cs‐oleate for Cs + or methylamine for MA + ) is quickly injected into a solution containing a metal halide salt (e.g., PbX 2 ) and capping ligands (e.g., alkyl chain amine and acid) at high temperature, resulting in the formation of ternary halide PNCs upon the rapid salts metathesis reaction (see Figure f) . The overall reaction mechanism of the hot injection method is illustrated in Figure e.…”

Metal‐Halide Perovskites: Emerging Light‐Emitting Materials

“…Direct synthesis of colloidal perovskite nanocrystals typically occurs via ligandassisted reprecipitation or hot injection. 1 For ligand-assisted reprecipitation, perovskite precursors (e.g., lead halide and organic halide salts) are dissolved in strong polar solvents and subsequently added to nonpolar solvents in the presence of ligands, often in large excess. The different solubility in polar and nonpolar solvents triggers the recrystallization of perovskite nanocrystals and the ligands prevent them from aggregating in bulky forms that would inhibit their ability to be suspended in a solution.…”