Fahima Ouchen

DNA Electron Injection Interlayers for Polymer Light-Emitting Diodes

Introduction of a DNA interlayer adjacent to an Al cathode in a polymer light-emitting diode leads to lower turn-on voltages, higher luminance efficiencies, and characteristics comparable to those observed using a Ba electrode. The DNA serves to improve electron injection and also functions as a hole-blocking layer. The temporal characteristics of the devices are consistent with an interfacial dipole layer adjacent to the electrode being responsible for the reduction of the electron injection barrier.

Modified processing techniques of a DNA biopolymer for enhanced performance in photonics applications

Significant modifications have been made in the processing techniques developed to transform purified, marine-based deoxyribonucleic acid (DNA) into a biopolymer suitable for optical and electronic device fabrication. This technique employs a modified soxhlet-dialysis rinsing process to completely remove excess ionic contaminants from the DNA biopolymer, resulting in a material with greater mechanical stability and enhanced performance reproducibility.

Deoxyribonucleic acid-ceramic hybrid dielectrics for potential application as gate insulators in organic field effect transistors

Hybrid films incorporating high dielectric constant k ceramics (BaTiO3 and TiO2) in deoxyribonucleic acid (DNA) were fabricated from highly stable dispersions of the ceramic nanoparticles in viscous, aqueous DNA solutions. Dielectric and electrical properties of the as-prepared nanocomposite films were investigated for potential use as gate insulators in organic field effect transistors. A k value as high as 14 was achieved with a 40 wt. % loading of ceramic nanoparticles in DNA. Electrical resistivities on the order of 1014 Ω cm with leakage current densities on the order of 10−9 A/cm2 were measured from current-voltage experiments under electric field biases up to 50 V/μm.

Dielectric and electrical properties of sol-gel/DNA blends

We investigate the dielectric and electrical properties of sol-gel/DNA-CTMA blends, with particular interest in capacitor applications in energy storage. Methacryloyloxypropyltrimethoxysilane (MAPTMS) was the sol-gel precursor, and DNA-CTMA was blended in to the resulting sol-gel at 5 weight%. The blend was then tested for its dielectric properties and dielectric breakdown strength; at frequencies below 10kHz the blend was found to have a dielectric constant in the range of 7.5, while the breakdown strength was greater than 800 V/μm, an exceptional value. We discuss these results as well as other aspects of the dielectric and electrical properties of these blends.

DNA thin films as semiconductors for BioFET

In this paper we report the latest results on DNA based field effect transistor. Blending DNA with either conductive polymers, carbon based nanoparticles or metal based compounds show an increase in surface conductivity and evidence of a field effect modulation of the drain-source currents.

Polymeric waveguide electro-optic beam-steering device with DNA biopolymer conductive cladding layers

Abstract. A polymer electro-optic (EO) waveguide beam-steering device with deoxyribonucleic acid (DNA) biopolymer conductive cladding layers and a core layer of the commercially available EO polymer SEO100 is demonstrated with 100% relative poling efficiency. This demonstration device exhibits a deflection efficiency of 99  mrad/kV with a corresponding in-device EO coefficient r33 of 124  pm/V at 1550 nm. When the DNA biopolymer bottom cladding layer is replaced by the commonly used cladding polymer UV15, the deflection efficiency and in-device r33 drop to 34  mrad/kV and 43  pm/V, respectively.

Hybrid DNA materials for energy storage

We investigate the dielectric and electrical properties of sol-gel/DNA-CTMA blends, with particular interest in capacitor applications in energy storage. Methacryloyloxypropyltrimethoxysilane (MAPTMS) was the solgel precursor, and DNA-CTMA was blended in to the resulting sol-gel at various weight percentages. The blends were tested for their dielectric properties and dielectric breakdown strength; the 5% DNA blend was found to be optimal with a dielectric constant in the range of 7.5, while the breakdown strength was greater than 800 V/μm for 1 μm films and about 500 V/μm for 5μm films. Hybrid sol-gel/DNA-CTMA/barium titanate nanoparticle composites were also formulated and their dielectric properties measured. While a high dielectric constant was achieved (38), this came at the expense of a significantly reduced breakdown voltage (160V/μm). We discuss these results as well as other aspects of the dielectric and electrical properties of these blends.

Deoxyribonucleic acid-based hybrid thin films for potential application as high energy density capacitors

Deoxyribonucleic acid (DNA) based hybrid films incorporating sol-gel-derived ceramics have shown strong promise as insulating dielectrics for high voltage capacitor applications. Our studies of DNA-CTMA (cetyltrimethylammonium) complex/sol-gel ceramic hybrid thin film devices have demonstrated reproducibility and stability in temperature- and frequency-dependent dielectric properties with dielectric constant k ∼ 5.0 (1 kHz), as well as reliability in DC voltage breakdown measurements, attaining values consistently in the range of 300–350 V/μm. The electrical/dielectric characteristics of DNA-CTMA films with sol-gel-derived ceramics were examined to determine the critical energy storage parameters such as voltage breakdown and dielectric constant.

Characterization of polymer, DNA-based, and silk thin film resistivities and of DNA-based films prepared for enhanced electrical conductivity

DC resistivity studies were carried out on biopolymer films of DNA-CTMA and silk fibroin, and on selected traditional polymer films, including PMMA and APC. Films of DNA-CTMA versus molecular weight and with conductive dopants PCBM, BAYTRON P and ammonium tetrachloroplatinate are reported. The films were spin coated on glass slides configured for measurements of volume dc resistance. The measurements used the alternating polarity method to record the applied voltage-dependent current independent of charging and background currents. The Arrhenius equation plus a constant was fitted to the conductivity versus temperature data of the polymers and the non-doped DNA-based biopolymers with activation energies ranging from 0.8 to 1.4 eV.

Latest advances in biomaterials: from deoxyribonucleic acid to nucleobases

This paper is a review of the recent research in bio-based materials for photonics and electronics applications. Materials that we have been working with include: deoxyribonucleic acid (DNA)-based biopolymers and nucleobases. We will highlight work on increasing the ionic conductivity of DNA-based membranes, enhancing the direct (DC) current and photoconductivity of DNA-based biopolymers, crosslinking of DNA-based biopolymers and promising applications for DNA nucleobases. Key