Researcher:
Sadeghi, Sadra

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PhD Student

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Sadra

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Sadeghi

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Sadeghi, Sadra

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2018 - 2019172020 - 202213

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Researcher Of Publications: search.filters.isAuthorOfPublication.34131bee-c39d-4f32-b871-a47a9bc81f2b

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Now showing 1 - 10 of 31
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    Colloidal aluminum antimonide quantum dots
    (Amer Chemical Soc, 2019) Sahin, Mehmet; Öztürk, Hande; Ow-Yang, Cleva W.; N/A; N/A; Department of Electrical and Electronics Engineering; Jalali, Houman Bahmani; Sadeghi, Sadra; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 130295
    AlSb is a less studied member of the III-V semiconductor family, and herein, we report the colloidal synthesis of AlSb quantum dots (QDs) for the first time. Different sizes of colloidal AlSb QDs (5 to 9 nm) were produced by the controlled reaction of AlCl3 and Sb[N(Si(Me)(3))(2)](3) in the presence of superhydride. These colloidal AlSb quantum dots showed excitonic transitions in the UV-A region and a tunable band edge emission (quantum yield of up to 18%) in the blue spectral range. Among all III-V quantum dots, these quantum dots show the brightest core emission in the blue spectral region.
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    Light-emitting devices based on Type-II InP/ZnO quantum dots
    (American Chemical Society (ACS), 2019) N/A; Department of Electrical and Electronics Engineering; N/A; N/A; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; Karatüm, Onuralp; Jalali, Houman Bahmani; Sadeghi, Sadra; Melikov, Rustamzhon; Srivastava, Shashi Bhushan; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; PhD Student; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 130295
    One of the major challenges for present-day quantum dot light-emitting diode (QLED) technology is the transition from toxic heavy metal to "green" material-based devices. This report proposes an alternative cadmium-free material of type-II InP/ZnO core/shell quantum dots (QDs) for QLEDs. In this study, InP/ZnO core/shell QDs are nanoengineered by adjusting the shell coverage for optimum in-film quantum efficiency, and device parameters are investigated to reach a maximum QLED performance. The fully solution processed QLEDs made of biocompatible and environmentally benign QDs presented in this study exhibit low turn on voltage of 2.8 V, external quantum efficiency of 0.53%, and current efficiency of 1 cd/A, with a saturated color emission in the yellow-orange spectral region. This study paves the way towards nontoxic and efficient LEDs using type-II QDs.
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    Radiative energy transfer in color-conversion LEDs
    (Optica Publishing Group (formerly OSA), 2018) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; Melikov, Rustamzhon; Press, Daniel Aaron; Kumar, Baskaran Ganesh; Sadeghi, Sadra; Nizamoğlu, Sedat; PhD Student; Researcher; Other; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; 130295
    We developed a matrix method that calculates and reveals all the radiative energy transfer processes of absorption, reabsorption, inter-absorption and their iterative and combinatorial interactions in down-conversion layer of a light-emitting diode.
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    Efficient nanocrystal-based white LEDs with suppressed absorption losses
    (Optica Publishing Group, 2022) Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Nizamoğlu, Sedat; Önal, Asım; Sadeghi, Sadra; Melikov, Rustamzhon; Faculty Member; PhD Student; PhD Student; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 130295; N/A; N/A; N/A
    We demonstrate efficient white LEDs by using the combination of green-emitting near-unity quantum dots with red-emitting nanorods. Stokes-shift in red via dot-to-rod transition reduced absorption losses and led to a high quantum efficiency of 42.9%.
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    Ultra-efficient and high-quality white light-emitting devices using fluorescent proteins in aqueous medium
    (Wiley, 2020) N/A; N/A; N/A; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Sadeghi, Sadra; Melikov, Rustamzhon; Çonkar, Deniz; Karalar, Elif Nur Fırat; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; 206349; 130295
    The transformation of electronics toward “green” and efficient devices is critical for the environmental sustainability and energy future. So far, majority of efficient lighting devices have been realized by artificial optical materials such as rare-earth-elements-doped phosphors, colloidal quantum dots (QDs) and dyes. In this study, red-emitting mScarlet and green-emitting eGFP fluorescent proteins are determined for high-performance white LEDs, expressed in living Escherichia coli and the purified proteins are integrated in their natural aqueous environment onto blue LED chips. The aqueous integration preserved quantum yield levels of the proteins above 70% in the device architecture and facilitated a high luminous efficiency (LE) of 81 lm W−1 with a color rendering index (CRI) of 83, which is the most efficient eco-friendly white LED reported to date. Moreover, the concentration ratio are also optimized of red- and green-emitting proteins and white protein-based LEDs with a maximum CRI of 92 are demonstrated. This study shows that fluorescent proteins hold great promise for the next generation eco-friendly, efficient and high-quality white light sources.
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    Excitonic energy transfer within inp/zns quantum dot langmuir-blodgett assemblies
    (Amer Chemical Soc, 2018) N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Jalali, Houman Bahmani; Melikov, Rustamzhon; Sadeghi, Sadra; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 130295
    Interparticle energy transfer offers great promise to a diverse range of applications ranging from artificial solar energy harvesting to nanoscale rulers in biology. Here, we assembled InP/ZnS core/shell quantum dot monolayers via the Langmuir-Blodgett technique and studied the effect of ZnS shell thickness on the excitonic energy transfer within these core/shell quantum dots. Three types of InP-based core/shell quantum dot Langmuir-Blodgett assemblies with different ZnS shell thicknesses were assembled. The structural and optical properties of colloidal quantum dots reveal the successful multiple ZnS shell growth, and atomic force microscopy studies show the smoothness of the assembled monolayers. Time-resolved photoluminescence (PL) and fluorescence lifetime imaging microscopy (FLIM) studies of the thick-shell QD monolayer reveal narrower lifetime distribution in comparison with the thin-shell QD monolayer. The interparticle excitonic energy transfer was studied by spectrally resolved traces, and higher energy transfer was observed for the thin-shell InP/1ZnS QD monolayer. Finally, we calculated the average exciton energy and indicated that the energy transfer induced exciton energy shift decreased significantly from 95 to 27 meV after multiple ZnS shell growth.
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    Stokes-shift-engineered indium phosphide quantum dots for efficient luminescent solar concentrators
    (American Chemical Society (ACS), 2018) Ow-Yang, Cleva W.; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; Sadeghi, Sadra; Jalali, Houman Bahmani; Melikov, Rustamzhon; Kumar, Baskaran Ganesh; Aria, Mohammad Mohammadi; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; Other; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; N/A; 130295
    Luminescent solar concentrators (LSCs) show promise because of their potential for low-cost, large-area, and high-efficiency energy harvesting. Stokes shift engineering of luminescent quantum dots (QDs) is a favorable approach to suppress reabsorption losses in LSCs; however, the use of highly toxic heavy metals in QDs constitutes a serious concern for environmental sustainability. Here, we report LSCs based on cadmium-free InP/ZnO core/shell QDs with type-II band alignment that allow for the suppression of reabsorption by Stokes shift engineering. The spectral emission and absorption overlap was controlled by the growth of a ZnO shell on an InP core. At the same time, the ZnO layer also facilitates the photostability of the QDs within the host matrix. We analyzed the optical performance of indium-based LSCs and identified the optical efficiency as 1.45%. The transparency, flexibility, and cadmium-free content of the LSCs hold promise for solar window applications.
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    Ecofriendly and efficient luminescent solar concentrators based on fluorescent proteins
    (amer Chemical Soc, 2019) N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; N/A; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Sadeghi, Sadra; Melikov, Rustamzhon; Jalali, Houman Bahmani; Karatüm, Onuralp; Srivastava, Shashi Bhushan; Çonkar, Deniz; Karalar, Elif Nur Fırat; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; PhD Student; Researcher; PhD Student; Faculty Member, Faculty Member; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 206349; 130295
    In recent years, luminescent solar concentrators (LSCs) have received renewed attention as a versatile platform for large-area, high-efficiency, and low-cost solar energy harvesting. So far, artificial or engineered optical materials, such as rare-earth ions, organic dyes, and colloidal quantum dots (QDs) have been incorporated into LSCs. Incorporation of nontoxic materials into efficient device architectures is critical for environmental sustainability and clean energy production. Here, we demonstrated LSCs based on fluorescent proteins, which are biologically produced, ecofriendly, and edible luminescent biomaterials along with exceptional optical properties. We synthesized mScarlet fluorescent proteins in Escherichia coli expression system, which is the brightest protein with a quantum yield of 61% in red spectral region that matches well with the spectral response of silicon solar cells. Moreover, we integrated fluorescent proteins in an aqueous medium into solar concentrators, which preserved their quantum efficiency in LSCs and separated luminescence and wave-guiding regions due to refractive index contrast for efficient energy harvesting. Solar concentrators based on mScarlet fluorescent proteins achieved an external LSC efficiency of 2.58%, and the integration at high concentrations increased their efficiency approaching to 5%, which may facilitate their use as “luminescent solar curtains” for in-house applications. The liquid-state integration of proteins paves a way toward efficient and “green” solar energy harvesting.
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    Erratum to: exciton recycling via InP quantum dot funnels for luminescent solar concentrators
    (Tsinghua University) Ow-Yang, Cleva W.; N/A; N/A; N/A; N/A; Department of Physics; Department of Electrical and Electronics Engineering; Jalali, Houman Bahmani; Sadeghi, Sadra; Toker, Işınsu Baylam; Han, Mertcan; Sennaroğlu, Alphan; Nizamoğlu, Sedat; PhD Student; PhD Student; PhD Student; Master Student; Faculty Member; Faculty Member; Department of Physics; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; N/A; N/A; 23851; 130295
    The article "Exciton recycling via InP quantum dot funnels for luminescent solar concentrators" written by Houman Bahmani Jalali(1),, Sadra Sadeghi(2),, Isinsu Baylam(3,4), Mertcan Han(5), Cleva W. Ow-Yang(6), Alphan Sennaroğlu(3,4), and Sedat Nizamoğlu(1,2,5) (x2709;), was originally published Online First without Open Access. After publication online first, the author decided to opt for Open Choice and to make the article an Open Access publication. Therefore, the copyright of the article has been changed to (c) The Author(s) 2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The original article has been corrected.
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    Effective neural photostimulation using indium-based type-ii quantum dots
    (American Chemical Society (ACS), 2018) Şahin, Mehmet; Ow-Yang, Cleva W.; N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; Department of Electrical and Electronics Engineering; Jalali, Houman Bahmani; Aria, Mohammad Mohammadi; Dikbaş, Uğur Meriç; Sadeghi, Sadra; Kumar, Baskaran Ganesh; Kavaklı, İbrahim Halil; Nizamoğlu, Sedat; PhD Student; PhD Student; Master Student; PhD Student; Other; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; N/A; 40319; 130295
    Light-induced stimulation of neurons via photoactive surfaces offers rich opportunities for the development of therapeutic methods and high-resolution retinal prosthetic devices. Quantum dots serve as an attractive building block for such surfaces, as they can be easily functionalized to match the biocompatibility and charge transport requirements of cell stimulation. Although indium based colloidal quantum dots with type-I band alignment have attracted significant attention as a nontoxic alternative to cadmium-based ones, little attention has been paid to their photovoltaic potential as type-II heterostructures. Herein, we demonstrate type-II indium phosphide/zinc oxide core/shell quantum dots that are incorporated into a photoelectrode structure for neural photostimulation. This induces a hyperpolarizing bioelectrical current that triggers the firing of a single neural cell at 4 mu W mm(-2), 26-fold lower than the ocular safety limit for continuous exposure to visible light. These findings show that nanomaterials can induce a biocompatible and effective biological junction and can introduce a route in the use of quantum dots in photoelectrode architectures for artificial retinal prostheses.