Small review: Role of ligands in lead-based perovskite nanocrystals—from synthesis to optoelectronic applications

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• In recent years, lead-based perovskite nanocrystals have been widely studied due to their excellent characteristics such as high carrier mobility, long diffusion distance, and high fluorescence quantum yield. However, unlike noble metal and chalcogenide NCs that are covalently bonded, perovskite NCs are mainly ionic bonded and their surface states are more complex, thus exhibiting different ligand-nanocrystal interactions.

  
  

  Semiconductor nanocrystals, also known as artificial atoms, have attracted widespread attention due to their size-tunable optoelectronic properties. The size of nanocrystals is generally several nanometers to tens of nanometers. Compared with bulk materials, nanocrystals have a larger specific surface area, so ligand coating is required to provide colloidal stability. In addition to providing colloidal stability, ligands play important roles throughout the life cycle of nanocrystals. Before the reaction, the ligand forms a precursor in solution by combining with the reagent. During the reaction, ligands can regulate the crystallization kinetics by affecting the supply rate of precursors and the formation of monomers, thereby affecting the size and shape of nanocrystals. In addition, the ligands can also act as capping agents to terminate the growth of nanocrystals. Even after synthesis, surface defects of nanocrystals can be eliminated by ligand post-treatment.

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• Firstly, the role of ligands in size and shape regulation is discussed starting from the controllable synthesis of perovskite nanocrystals. Then, the bonding methods of ligands and the surface of perovskite nanocrystals are summarized, and the current popular ligand passivation and post-treatment methods are sorted out. The passivation and electrical transport properties of ligands have an important impact on the performance of optoelectronic devices, so the author discusses the carrier generation and recombination kinetics involved in optoelectronic devices, and summarizes photodetectors, The latest advances in applications such as solar cells, light-emitting diodes, and lasers. Finally, the author pointed out the existing problems and challenges from three perspectives: controllable synthesis of nanocrystals, surface binding of ligands, and optoelectronic applications.

• Wenda Sun, Rui Yun, Yuling Liu, Xiaodan Zhang, Mingjian Yuan, Libing Zhang, Xiyan Li*，Ligands in Lead Halide Perovskite Nanocrystals: From Synthesis to Optoelectronic Applications， Small，2023.

  DOI: 10.1002/smll.202205950

  https://onlinelibrary.wiley.com/doi/10.1002/smll.202205950