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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. 

Colloidal quantum dots (QDs) exhibit several advantageous photophysical properties combined with a high surface-to-volume ratio, making them very attractive for use in processes relying on energy-transfer (ET) interactions. We have tested the effectiveness of CsPbBr3 perovskite quantum dots (PQDs) as energy-transfer donors in hybrid PQD−dye assemblies. We combined PQDs and various cyanine dye molecules that present zwitterionic moieties and/or salt groups to promote tailored binding via electrostatic interactions and control the spectral overlap in PQD−dye pairs. This enabled the manipulation of the donor−acceptor stoichiometry of the assemblies. Using steady-state and time-resolved fluorescence spectroscopy, we evaluated the impact of varying the dye structure, photophysical characteristics, and dye-to-PQD ratio on the fluorescence properties of these hybrid conjugates. We find that the fluorescence quenching efficiency measured for these assemblies depends on key parameters, such as spectral overlap and number of dyes per assembly (or valence). Thorough analysis of our results indicates that invoking the Förster dipole−dipole and Dexter charge-transfer interaction mechanisms provides the best interpretation of the energy-transfer interaction in these donor−acceptor assemblies. 

There has been much interest in integrating various inorganic nanoparticles (nanoscale colloids) in biology and medicine. However, buildup of a protein corona around the nanoparticles in biological media, driven by nonspecific interactions, remains a major hurdle for the translation of nanomedicine into clinical applications. In this study, we investigate the interactions between gold nanoparticles and serum proteins using a series of dihydrolipoic acid (DHLA)-based ligands. We employed gel electrophoresis combined with UV−vis absorption and dynamic light scattering to correlate protein adsorption with the nature and size of the ligand used. For instance, we found that AuNPs capped with DHLA alone promote nonspecific protein adsorption. In comparison, capping AuNPs with polyethylene glycol- or zwitterion-appended DHLA essentially prevents corona formation, regardless of ligand charge and size. Our results highlight the crucial role of surface chemistry and core material in protein corona formation and offer valuable information for the design of colloidal nanomaterials for biological applications. 

Despite the impressive development of perovskite light-emitting diodes (PeLEDs), it is still challenging to achieve high-efficiency deep-blue PeLEDs using colloid perovskite quantum dots (PQDs). The efficiency of PQDs with a wavelength below 460 nm, which meets the requirements for deep-blue emission in the Telecommunication Union UHD television standard (ITU REC. 2020), lags far behind those of their sky-blue counterparts. To address this issue, a novel strategy of fast anion-exchange & cation-doping inter-promotion (FAECDIP) is proposed to achieve highly efficient deep-blue PQDs by introducing CaBr2 into the CsPbCl3 PQDs. Owing to the presence of Ca2+, the speed of ion exchange is increased, driven by the smaller cation, Ca2+, improving the preparation efficiency. Additionally, Ca2+ was doped on the surface of PQDs. Based on studies of fast anion-exchange and theoretical calculations, Ca2+ improves the optical performance by decreasing the number of traps and increasing the crystallinity of target PQDs, facilitating the stability of treated films and PeLEDs by enhancing the formation energy of halogen vacancies. Here, a high PLQY of 80.3 % CaBr2-induced CsPb(Cl/Br)3 deep-blue PQDs (~446 nm) was achieved. The correspondent PeLEDs (~447 nm) achieved a superior EQE of 5.88 %, which is the state-of-the-art among the reported deep-blue PeLEDs. Our strategy provides a potential route to achieve deep-blue PeLEDs, which differs from the previous tedious-complex methods. 

To stabilize and transport them through complex systems, nanoparticles are often encapsulated in polymeric nanocarriers, which are tailored to specific environments. For example, a hydrophilic polymer capsule maintains circulation and stability of nanoparticles in aqueous environments. A more highly-designed nanocarrier might have a hydrophobic core and a hydrophilic shell to allow transport of hydrophobic nanoparticles and pharmaceuticals through physiological media. Polydimethylsiloxane, PDMS, is a hydrophobic material in a liquidlike state at room temperature. The preparation of stable, aqueous dispersions of PDMS droplets in water is problematic due to the intense mismatch in surface energies between PDMS and water. The present work describes the encapsulation of hydrophobic metal- and metal oxide nanoparticles within PDMS nanodroplets using flash nanoprecipitation. The PDMS is terminated by amino groups and the nanodroplet is capped with a layer of poly(styrene sulfonate), forming a glassy outer shell. The hydrophobic nanoparticles nucleate PDMS droplet formation, decreasing the droplet size. The resulting nanocomposite nanodroplets are stable in aqueous salt solutions without the use of surfactants. The hierarchical structuring, elucidated with small angle x-ray scattering, offers a new platform for the isolation and transport of hydrophobic molecules and nanoparticles through aqueous systems.