Netta Hendler

Efficient Separation of Dyes by Mucin: Toward Bioinspired White‐Luminescent Devices

The production of organic white-light-emitting devices is one of the main technological and scientifi c challenges in the fi eld of optoelectronics [ 1–4 ] because the formation of such a broad emission spectrum with the use of a single dye is diffi cult to accomplish. [ 5 , 6 ] In practice, the emission of white light is achieved by the use of a mixture of the three primary dyes, which emit red (R), green (G), and blue (B) light. [ 7 ] However, as a result of nonradiative interactions between very close color elements, such as Förster resonance energy transfer (FRET), an undesirable shift in the emission spectrum is often observed, which prevents the achievement of white-light emission. [ 8 ]

Mucin complexes of nanomaterials: first biochemical encounter.

In recent years, the exposure of biological systems to various nanomaterials has become an issue of great public concern. Although living organisms have arrays of biological defense mechanisms against exposure to exogenous compounds, the biochemical mechanisms allowing various nanomaterials to enter the body are not well understood. A unique example of a typical mucosal glycoprotein capable of binding and solubilizing nanomaterials in physiological solution is provided, suggesting a possible route for entry into biological systems.

UV induced formation of transparent Au–Ag nanowire mesh film for repairable OLED devices

The next generation of optoelectronic devices requires transparent conductive electrodes to be flexible, cheap, and compatible with large scale manufacturing processes. Indium Tin Oxide (ITO) electrodes are often used due to their superior transparency and conductance, however they are brittle, expensive and their fabrication requires vacuum conditions which restrict scale-up. One possible alternative to the traditional ITO electrode is the metal nanowire mesh (MNWM) electrode, which is transparent, conductive, flexible and easy to produce. In this work we present the preparation and characterization of a simple organic light emitting diode (OLED) device based on a transparent electrode made of ultrathin MNWM and a comparison to an ITO based device. We have found that MNWM electrodes offer a suitable alternative to ITO electrodes in OLED devices. We have also found that the failure rate for devices due to short circuits between the top and bottom electrodes was smaller in MNWM based devices compared to ITO based devices since the MNWM devices could be repaired to present normal OLED behavior by selectively burning the nanowires forming the short. The ability to “heal” organic devices presents an important advantage and also allows for future uses in applications such as roll to roll printing.

Efficient Separation of Conjugated Polymers Using a Water Soluble Glycoprotein Matrix: From Fluorescence Materials to Light Emitting Devices

Optically active bio-composite blends of conjugated polymers or oligomers are fabricated by complexing them with bovine submaxilliary mucin (BSM) protein. The BSM matrix is exploited to host hydrophobic extended conjugated π-systems and to prevent undesirable aggregation and render such materials water soluble. This method allows tuning the emission color of solutions and films from the basic colors to the technologically challenging white emission. Furthermore, electrically driven light emitting biological devices are prepared and operated.

Growth control of peptide-nanotube spherulitic films: Experiments and simulations

Multi-hierarchical self-assembly (MHSA) is a key process responsible for the spontaneous formation of many complex structures. However, because of the complexity of the process, the underlying mechanism remains largely unclear. Thus, a deeper understanding of MHSA is required, especially for the preparation of MHSA systems via bottom-up methodologies. We show here, experimentally and theoretically, that the complex-formation MHSA of peptide nanotube films can be controlled solely by manipulating the experimental parameter of humidity. Furthermore, we identify growth-front nucleation (GFN; the formation of new grains at the perimeter) as the physical background for the observed morphological transitions by correlating experimental observations with phase-field modeling of the morphological evolution. Our findings indicate a simple way to control multi-hierarchical morphologies, crucial for the employment of bottom-up techniques in constructing complex structures for practical applications.

Controlled electroluminescence from films composed of mixed bio-composites and nanotubes.

Good things come in threes: A new type of light emitting bio-composites allowing for the nanometric separation of the active components is demonstrated. A protein with large host-guest capacities is used for the encapsulation of a water-soluble composite dye in a nano-sized shell, which efficiently reduces Förster resonance energy transfer and related mechanisms. Blending of this bio-composite with multi-walled nanotubes increases the charge injection efficiency, in the electro-luminescent device.

Manipulation of second harmonic generation from metasurfaces

We manipulate the second harmonic generation (SHG) near-field and far-field radiation properties from metasurfaces composed of split ring resonators (SRRs). The manipulation is done by inverting the symmetry of the SRRs in periodic manner. We show by numerical models and experimentally that by that the nonlinear emission can be directed and that the emission direction can be controlled by changing the properties of the arrays or by changing the wavelength of the exciting beam at the first harmonic. This can be used as a new form of all-optical nonlinear scanner based on extremely thin metasurface. These methods open the door for development of new integrated nonlinear active devices based on metasurfaces and can be used to enhance the efficiency of the nonlinear output, therefore it provides a major step forward towards the development of efficient nonlinear metamaterials.