Gulis Zengin

Bilkent University, Ankara, Ankara, Turkey

Are you Gulis Zengin?

Claim your profile

Publications (6)20.04 Total impact

  • Source
    [show abstract] [hide abstract]
    ABSTRACT: The assembly kinetics of colloidal semiconductor quantum dots (QDs) on solid inorganic surfaces is of fundamental importance for implementation of their solid-state devices. Herein an inorganic binding peptide, silica binding QBP1, was utilized for the self-assembly of nanocrystal quantum dots on silica surface as a smart molecular linker. The QD binding kinetics was studied comparatively in three different cases: first, QD adsorption with no functionalization of substrate or QD surface; second, QD adsorption on QBP1-modified surface; and, finally, adsorption of QBP1-functionalized QD on silica surface. The surface modification of QDs with QBP1 enabled 79.3-fold enhancement in QD binding affinity, while modification of a silica surface with QBP1 led to only 3.3-fold enhancement. The fluorescence microscopy images also supported a coherent assembly with correspondingly increased binding affinity. Decoration of QDs with inorganic peptides was shown to increase the amount of surface-bound QDs dramatically compared to the conventional methods. These results offer new opportunities for the assembly of QDs on solid surfaces for future device applications.
    Langmuir 03/2011; 27(8):4867-72. · 4.19 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Semiconductor nanocrystal quantum dots are utilized in numerous applications in nano- and biotechnology. In device applications, where several different material components are involved, quantum dots typically need to be assembled at explicit locations for enhanced functionality. Conventional approaches cannot meet these requirements where assembly of nanocrystals is usually material-nonspecific, thereby limiting the control of their spatial distribution. Here we demonstrate directed self-assembly of quantum dot emitters at material-specific locations in a color-conversion LED containing several material components including a metal, a dielectric, and a semiconductor. We achieve a spatially selective immobilization of quantum dot emitters by using the unique material selectivity characteristics provided by the engineered solid-binding peptides as smart linkers. Peptide-decorated quantum dots exhibited several orders of magnitude higher photoluminescence compared to the control groups, thus, potentially opening up novel ways to advance these photonic platforms in applications ranging from chemical to biodetection.
    ACS Nano 02/2011; 5(4):2735-41. · 12.06 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: In our study, we investigated the quantum dots integrated with silica binding peptides on silica surface for three different assembly approaches. We used biotinylated silica binding peptides (SBP-bio) as smart linkers to immobilize quantum dots and streptavidin functionalized CdSe/ZnS core-shell quantum dots (SA-QD) as light emitters.
    Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS 01/2009;
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Warm-white light emitting diodes with high color rendering indices are required for the widespread use of solid state lighting especially indoors. To meet these requirements, we propose and demonstrate warm-white hybrid light sources that incorporate the right color-converting combinations of CdSe/ZnS core-shell nanocrystals hybridized on InGaN/GaN LEDs for high color rendering index. Three sets of proof-of-concept devices are developed to generate high-quality warm-white light with (1) tristimulus coordinates (x,y) = (0.37,0.30), luminous efficacy (LE) = 307 lm/W, color rending index (CR) = 82.4, and correlated color temperature (CCT) = 3228 K; (2) (x,y) = (0.38,0.31), LE = 323 lm/W, CRI = 81.0, and CCT = 3190 K; and (3) (x,y) = (0.37,0.30), LE = 303 lm/W, CRI = 79.6, and CCT = 1982 K.
    Applied Physics Letters 01/2008; 92(3):031102-031102-3. · 3.79 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: By hybridizing custom-design CdSe/ZnS core-shell NC emitters on InGaN/GaN based blue LEDs, we demonstrated three warm-white light sources with desirably low CCT ranging from 3227 K to 1982 K as is required for SSL indoor applications. In these proof-of-concept demonstrations, high color rendering indices (82.4) and high luminous efficacies of emitted spectra (327 lm/W) were achieved, while the color temperature was simultaneously kept low as desired. Our proof-of-concept demonstrations indicated that such nanocrystal luminophor based warm-white LEDs with high-quality photometric properties hold great promise especially for future indoor lighting applications.
    01/2008;
  • [show abstract] [hide abstract]
    ABSTRACT: We demonstrated material-specific binding of the quantum dot emitters hybridized with GEPI on multi-material patterned microchips. These proof-of-concept results open up new opportunities in nanophotonics, allowing for more specific and controlled assembly of quantum dots in optoelectronic devices and building of novel molecular organic-inorganic hybrid devices.
    01/2008;