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Metal halide perovskite quantum dots (PQDs) and perovskite magic sized clusters (PMSCs) exhibit interesting size- and composition-dependent optoelectronic properties that are promising for emerging applications including photovoltaic solar cells and light-emitting diodes (LEDs). Much work has focused on developing new synthesis strategies to improve their structural stability and property tunability. In this paper, we review recent progress in the synthesis and characterization of PQDs and PMSCs, with a focus on the impact of different molecular ligands on their surface passivation and interconversion. Moreover, the effect of capping ligands on ion exchange during synthesis and doping is discussed. Finally, we present some perspectives on challenges and opportunities in fundamental studies and potential applications of both PQDs and PMSCs.

Mn2+-doped amino lead halide molecular clusters (MCs) are synthesized using amine (e.g., n-octylamine, or butylamine) as passivating ligand and MnX2 (X = Cl or Br) as the Mn2+ doping source at room temperature. Their optical properties are investigated with UV–visible absorption, photoluminescence (PL), and PL excitation spectroscopy. The Mn2+ precursor plays a vital role in the synthesis of Mn2+-doped MCs. MnCl2 seems to facilitate the incorporation of Mn. The MnCl2 doping causes electronic absorption blue shift and leads to a spin-forbidden 4T1 → 6A1 Mn d-electron emission. With the help of time-resolved PL, Fourier transform infrared, and electron paramagnetic resonance results, a model is proposed to explain the formation mechanism. We suggest that Mn2+ doping replaces Pb2+ is assisted by Cl– ions that replace Br– ions. This study demonstrates the possibility of doping MCs and has important implications in gaining new fundamental insight into the growth mechanisms of perovskite nanostructures.

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