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1. Polycarboxybetaine Ligands Impart Structural Homogeneity and Improved Fluorescence Properties onto Hybrid Perovskite Nanocrystals

   https://doi.org/10.1021/acs.jpcc.5c02594  

   Donmez, Selin E; Wang, Sisi; Vorajee, Unaisah; Chen, Banghao; Mattoussi, Hedi (May 2025, The Journal of Physical Chemistry C)

   Room-temperature growth of colloidal hybrid organic− inorganic perovskite nanocrystals (PNCs) relying on ligandassisted reprecipitation, originally reported by Perez-Prieto and coworkers, preceded the development of the more explored allinorganic analogues developed by Kovalenko’s group. However, this method could not produce homogeneous and colloidally stable PNC dispersions, which further impeded fundamental investigations and slowed their integration into optoelectronic devices. We hereby introduce a strategy to address this problem by reacting the as-grown PNCs with a novel set of polyzwitterionic polymer ligands. The ligands incorporate a stoichiometric mixture of carboxybetaine groups and octylamine solubilizing moieties. We find that mixing as-grown dispersions of hybrid MAPbBr3 PNCs with polycarboxybetaine ligands triggers rapid transformation of the nanocrystals, yielding homogeneous nanocrystal shape, morphology, and size, combined with narrow PL profiles and increased quantum yields. We attribute this result to enhanced electrostatic interactions of the multidentate ligands with PNC surfaces. These cooperative interactions result in progressive size and shape focusing of the NCs with reaction time. The NC transformation is further coupled with better electronic passivation of surface defects, ensuring long-term colloidal, structural, and photophysical stability. 

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2. Metal Halide Perovskite Nanocrystals for Near-Infrared Circularly Polarized Luminescence with High Photoluminescence Quantum Yield via Chiral Ligand Exchange

   https://doi.org/10.1021/acs.jpclett.3c01184  

   Wei, Jianwu; Luo, Qiulian; Liang, Sengui; Zhou, Liya; Chen, Peican; Pang, Qi; Zhang, Jin Zhong (June 2023, The Journal of Physical Chemistry Letters)

   Using ligand exchange on FAPbI3 perovskite nanocrystals (PNCs) surface with chiral tridentate L-cysteine (Lcys) ligand, we successfully prepared chiral FAPbI3 PNCs that show circularly polarized luminescence (CPL) (dissymmetry factor; glum = 2.1 × 10−3) in the near-infrared (NIR) region from 700 to 850 nm and a photoluminescence quantum yield (PLQY) of 81%. The chiral characteristics of FAPbI3 PNCs are ascribed to induction by chiral L/D-cys, and the high PLQY is attributed to the passivation of the PNCs defects with L-cys. Also, effective passivation of defects on the surface of FAPbI3 PNCs by L-cys results in excellent stability toward atmospheric water and oxygen. The conductivity of the L-cys treated FAPbI3 NC films is improved, which is attributed to the partial substitution of L-cys for the insulating long oleyl ligand. The CPL of the L-cys ligand treated FAPbI3 PNCs film retains a glum of −2.7 × 10−4. This study demonstrates a facile yet effective approach to generating chiral PNCs with CPL for NIR photonics applications. 

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3. MAPbBr ₃ nanocrystals from aqueous solution for poly(methyl methacrylate)-MAPbBr ₃ nanocrystal films with compression-resistant photoluminescence

   https://doi.org/10.1088/1361-6528/ac59e8  

   Tang, Xiaobing; Zhang, Yulin; Kothalawala, Nadeesha Lakmali; Wen, Xiyu; Kim, Doo Young; Yang, Fuqian (March 2022, Nanotechnology)

   Abstract In this work, we develop an environmental-friendly approach to produce organic-inorganic hybrid MAPbBr 3 (MA = CH 3 NH 3 ) perovskite nanocrystals (PeNCs) and PMMA-MAPbBr 3 NC films with excellent compression-resistant PL characteristics. Deionized water is used as the solvent to synthesize MAPbBr 3 powder instead of conventionally-used hazardous organic solvents. The MAPbBr 3 PeNCs derived from the MAPbBr 3 powder exhibit a high photoluminescence quantum yield (PLQY) of 93.86%. Poly(methyl methacrylate) (PMMA)-MAPbBr 3 NC films made from the MAPbBr 3 PeNCs retain ∼97% and ∼91% of initial PL intensity after 720 h aging in ambient environment at 50 °C and 70 °C, respectively. The PMMA-MAPbBr 3 NC films also exhibit compression-resistant photoluminescent characteristics in contrast to the PMMA-CsPbBr 3 NC films under a compressive stress of 1.6 MPa. The PMMA-MAPbBr 3 NC film integrated with a red emissive film and a blue light emitting source achieves an LCD backlight of ∼114% color gamut of National Television System Committee (NTSC) 1953 standard. 

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4. Doping and ion substitution in colloidal metal halide perovskite nanocrystals

   https://doi.org/10.1039/C9CS00790C  

   Lu, Cheng-Hsin; Biesold-McGee, Gill V.; Liu, Yijiang; Kang, Zhitao; Lin, Zhiqun (July 2020, Chemical Society Reviews)

   null (Ed.)

   The past decade has witnessed tremendous advances in synthesis of metal halide perovskites and their use for a rich variety of optoelectronics applications. Metal halide perovskite has the general formula ABX 3 , where A is a monovalent cation (which can be either organic ( e.g. , CH 3 NH 3 + (MA), CH(NH 2 ) 2 + (FA)) or inorganic ( e.g. , Cs + )), B is a divalent metal cation (usually Pb 2+ ), and X is a halogen anion (Cl − , Br − , I − ). Particularly, the photoluminescence (PL) properties of metal halide perovskites have garnered much attention due to the recent rapid development of perovskite nanocrystals. The introduction of capping ligands enables the synthesis of colloidal perovskite nanocrystals which offer new insight into dimension-dependent physical properties compared to their bulk counterparts. It is notable that doping and ion substitution represent effective strategies for tailoring the optoelectronic properties ( e.g. , absorption band gap, PL emission, and quantum yield (QY)) and stabilities of perovskite nanocrystals. The doping and ion substitution processes can be performed during or after the synthesis of colloidal nanocrystals by incorporating new A′, B′, or X′ site ions into the A, B, or X sites of ABX 3 perovskites. Interestingly, both isovalent and heterovalent doping and ion substitution can be conducted on colloidal perovskite nanocrystals. In this review, the general background of perovskite nanocrystals synthesis is first introduced. The effects of A-site, B-site, and X-site ionic doping and substitution on the optoelectronic properties and stabilities of colloidal metal halide perovskite nanocrystals are then detailed. Finally, possible applications and future research directions of doped and ion-substituted colloidal perovskite nanocrystals are also discussed. 

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5. Ultra-stable blue-emitting lead-free double perovskite Cs ₂ SnCl ₆ nanocrystals enabled by an aqueous synthesis on a microfluidic platform

   https://doi.org/10.1039/D2NR05510D  

   Tang, Xiaobing; Wen, Xiyu; Yang, Fuqian (December 2022, Nanoscale)

   Blue emitting Sn-based lead-free halide perovskite nanocrystals (NCs) are considered to be a promising material in lighting and displays. However, industrialised fabrication of blue-emitting NCs still remains a significant challenge due to the use of toxic solvents and optical instability, not mentioning in large-scale synthesis. In this work, a green-route synthesis of blue-emitting lead-free halide perovskite Cs 2 SnCl 6 powders is developed, in which deionized water with a small amount of inorganic acid is used as the solvent and the synthesis of the Cs 2 SnCl 6 powders is achieved on a microfluidic platform. Using the Cs 2 SnCl 6 powders, we prepare Cs 2 SnCl 6 NCs via an ultrasonication process. Changing the volume ratio of the ligands (oleic acid to oleylamine) can alter the photoluminescence (PL) characteristics of the prepared NCs, including the PL-peak wavelength, PL-peak intensity and quantum yield. The highest photoluminescence quantum yield (PLQY) of 13.4% is achieved by the Cs 2 SnCl 6 NCs prepared with the volume ratio of oleic acid to oleylamine of 40 μL to 10 μL. A long-term PL stability test demonstrates that the as-synthesized Cs 2 SnCl 6 NCs can retain a stable PLQY over a period of 60 days. This work opens up a new path for a large-scale green-route synthesis of blue-emitting Sn-based lead-free NCs, such as Cs 2 SnX 6 (Cl, Br and I), towards their applications in optoelectronics. 

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