Photon Recycling in CsPbBr All-Inorganic Perovskite Nanocrystals.

Photon recycling, the iterative process of re-absorption and re-emission of photons in an absorbing medium, can play an important role in the power-conversion efficiency of photovoltaic cells. To date, several studies have proposed that this process may occur in bulk or thin films of inorganic lead-halide perovskites, but conclusive proof of the occurrence and magnitude of this effect is missing. Here, we provide clear evidence and quantitative estimation of photon recycling in CsPbBr nanocrystal suspensions by combining measurements of steady-state and time-resolved photoluminescence (PL) and PL quantum yield with simulations of photon diffusion through the suspension.

Direct Visualization and Determination of the Multiple Exciton Generation Rate.

Multiple exciton generation (MEG) takes place in competition to other hot carrier cooling processes. While the determination of carrier cooling rates is well established, direct information on MEG dynamics has been lacking. Here, we present a methodology to obtain the MEG rate directly in the initial ultrafast transient absorption dynamics.

Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating.

Inorganic perovskites display an enticing foreground for their wide range of optoelectronic applications. Recently, supercrystals (SCs) of inorganic perovskite nanocrystals (NCs) have been reported to possess highly ordered structure as well as novel collective optical properties, opening new opportunities for efficient films. Here, we report the large-scale assembly control of spherical, cubic, and hexagonal SCs of inorganic perovskite NCs through templating by oil-in-oil emulsions.

Efficient carrier multiplication in CsPbI perovskite nanocrystals.

The all-inorganic perovskite nanocrystals are currently in the research spotlight owing to their physical stability and superior optical properties-these features make them interesting for optoelectronic and photovoltaic applications. Here, we report on the observation of highly efficient carrier multiplication in colloidal CsPbI nanocrystals prepared by a hot-injection method. The carrier multiplication process counteracts thermalization of hot carriers and as such provides the potential to increase the conversion efficiency of solar cells.

Correction to "Hybridization of Single Nanocrystals of CsPbBr and CsPbBr".

[This corrects the article DOI: 10.1021/acs.jpcc.

Extraordinary Interfacial Stitching between Single All-Inorganic Perovskite Nanocrystals.

All-inorganic cesium lead halide perovskite nanocrystals are extensively studied because of their outstanding optoelectronic properties. Being of a cubic shape and typically featuring a narrow size distribution, CsPbX (X = Cl, Br, and I) nanocrystals are the ideal starting material for the development of homogeneous thin films as required for photovoltaic and optoelectronic applications. Recent experiments reveal spontaneous merging of drop-casted CsPbBr nanocrystals, which is promoted by humidity and mild-temperature treatments and arrested by electron beam irradiation.

Hybridization of Single Nanocrystals of CsPbBr and CsPbBr.

Nanocrystals of all-inorganic cesium lead halide perovskites (CsPbX, X = Cl, Br, I) feature high absorption and efficient narrow-band emission which renders them promising for future generation of photovoltaic and optoelectronic devices. Colloidal ensembles of these nanocrystals can be conveniently prepared by chemical synthesis. However, in the case of CsPbBr, its synthesis can also yield nanocrystals of CsPbBr and the properties of the two are easily confused.

Color-stable water-dispersed cesium lead halide perovskite nanocrystals.

Cesium lead halide perovskite nanocrystals are being lately explored for optoelectronic applications due to their emission tunability, high photoluminescence quantum yields, and narrow emission bands. Nevertheless, their incompatibility with polar solvents and composition homogenization driven by a fast anion-exchange are still important drawbacks to overcome. Herein we report on a successful encapsulation of colloidal perovskite nanocrystals within solid-lipid structures mainly consisting of stearic acid.

Direct Observation of Band Structure Modifications in Nanocrystals of CsPbBr Perovskite.

We investigate the variation of the bandgap energy of single quantum dots of CsPbBr inorganic halide perovskite as a function of size and shape and upon embedding within an ensemble. For that purpose, we make use of valence-loss electron spectroscopy with Z-contrast annular dark-field (ADF) imaging in a state-of-the-art low-voltage monochromatic scanning transmission electron microscope. In the experiment, energy absorption is directly mapped onto individual quantum dots, whose dimensions and location are simultaneously measured to the highest precision.

Magneto-plasmonic nanoparticles as theranostic platforms for magnetic resonance imaging, drug delivery and NIR hyperthermia applications.

PEGylated magneto-plasmonic nanoparticles with a hollow or semi-hollow interior have been successfully synthesized and their physico-chemical characteristics have been investigated. The hollow interior space can be used to store drugs or other molecules of interest whereas magnetic characterization shows their potential as contrast agents in magnetic resonance imaging (MRI) applications. In addition, their plasmonic characteristics in the near infrared (NIR) region make them efficient in photothermal applications producing high temperature gradients after short irradiation times.

Temporal and spatial patterning of transgene expression by near-infrared irradiation.

We investigated whether near-infrared (NIR) light could be employed for patterning transgene expression in plasmonic cell constructs. Hollow gold nanoparticles with a plasmon surface band absorption peaking at ∼750 nm, a wavelength within the so called "tissue optical window", were used as fillers in fibrin-based hydrogels. These composites, which efficiently transduce NIR photon energy into heat, were loaded with genetically-modified cells that harbor a heat-activated and ligand-dependent gene switch for regulating transgene expression.

Plasmon-enhanced photocatalytic water purification.

Increasing water demand and water scarcity around the world requires the development of robust and efficient methods for water purification in the coming decades. Here, we report a photocatalytic water purification method using visible light (532 nm) utilizing 5 nm gold nanoparticles and their enhancement when attached on the surface of silica nanospheres as an inactive support to prevent nanoparticle coalescence or sintering. This is a non-toxic, low-cost, and easy photocatalytic process which provides high decomposition rates.

Near-infrared-actuated devices for remotely controlled drug delivery.

A reservoir that could be remotely triggered to release a drug would enable the patient or physician to achieve on-demand, reproducible, repeated, and tunable dosing. Such a device would allow precise adjustment of dosage to desired effect, with a consequent minimization of toxicity, and could obviate repeated drug administrations or device implantations, enhancing patient compliance. It should exhibit low off-state leakage to minimize basal effects, and tunable on-state release profiles that could be adjusted from pulsatile to sustained in real time.

Au-PLA nanocomposites for photothermally controlled drug delivery.

Stimuli-responsive drug delivery systems were obtained by encapsulating near-infrared (NIR) sensitive hollow gold nanoshells (HGNs) together with the molecule to be released into biodegradable poly-lactic acid (PLA) sub-micron particles. The rapid heating of the PLA particles caused by NIR radiation enabled use of the PLA-HGN composites as a photo-triggered drug release system. Rhodamine was used as a test molecule to obtain release profiles under different irradiation conditions.

Scaled-up production of plasmonic nanoparticles using microfluidics: from metal precursors to functionalized and sterilized nanoparticles.

An exquisite control of synthesis parameters is generally required in nanomaterial synthesis to guarantee consistency in the essential characteristics such as size and shape. On the other hand, reliable scaled-up production of nanomaterials is required in order to achieve the production rates required for emerging nanotechnology applications while delivering a consistent product with the intended characteristics, avoiding the traditional batch-to-batch deviations. The continuous production of nanomaterials is challenging because of the difficulties involved in translating the complexity of nanomaterial synthesis into on-line operations.

Enhancing of plasmonic photothermal therapy through heat-inducible transgene activity.

Unlabelled: We explore the synergistic effect of photothermal therapy and gene therapy, simultaneously triggered by silica-gold nanoshells (NS) or hollow gold nanoparticles (HGNPs) in human HeLa cells following near-infrared (NIR) light irradiation. Thermal transfer from NS was higher than that displayed by HGNPs, owing to a differential interaction of the nanomaterial with the biological environment. Under sublethal photothermal conditions, NS and HGNPs effectively modulated the expression levels of a DsRed-monomer reporter gene controlled by the highly heat-inducible human HSP70B promoter, as a function of nanomaterial concentration and length of laser exposure.