Photonics / Fotonik

Permanent URI for this collectionhttps://hdl.handle.net/11147/2590

Browse

Filters

2016 - 20193

Settings

Author: search.filters.author.Varlıklı, CananPublisher: search.filters.publisher.Elsevier Ltd.

Search Results

Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 30
    Citation - Scopus: 32
    Perylene-Embedded Electrospun Ps Fibers for White Light Generation
    (Elsevier Ltd., 2019) Güner, Tuğrul; Demir, Mustafa Muammer; Aksoy, Erkan; Varlıklı, Canan; Demir, Mustafa Muammer; Varlıklı, Canan; 04.04. Department of Photonics; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    Perylene dyes have been employed in the fabrication of white light due to their superior photophysical properties and relatively easy synthetic methods. However, their molecular aggregation in solid state is one of the main handicaps since it causes deviation in their optical properties and quenches photoluminescence quantum yields (Phi(f)). Investigation of the photophysical properties of a green (PTE), a yellow (PDI) and a new red (DiPhAPDI) emitting perylene derivative in solution, drop-casted films, polystyrene (PS) fibers and PS fibers embedded in poly (dimethyl siloxane) (PDMS) showed that PS:dye fibers prevent aggregation to some extend and allows high Of of dyes. The Of values of PTE, PDI and DiPhAPDI were all higher than 93.0% in solution and 84.8%, 94.3% and 73.6%, respectively in PS:dye fibers. Embedding the fibers in PDMS improved the photostabilities of the dyes two folds compared to their solution phases. The prepared dye containing fibers were combined together into a single PDMS film and utilized as a frequency conversion layer on a blue LED. Fabricated samples were found to show high color rendering index (>= 90), adjustable CCT (7500 K-5000 K), and power efficiency values exceeding 2001m/W depending on the used fiber amount in mass.
  • Article
    Citation - WoS: 19
    Citation - Scopus: 20
    Controlling the Distribution of Oxygen Functionalities on Go and Utilization of Pedot:pss-Go Composite as Hole Injection Layer of a Solution Processed Blue Oled
    (Elsevier Ltd., 2017) Diker, Halide; Diker, Halide; Varlıklı, Canan; Yeşil, Fatih; Varlıklı, Canan; 01. Izmir Institute of Technology; 04.04. Department of Photonics; 04. Faculty of Science
    Graphene oxide (GO) was synthesis by Tour method. Particle size distribution effects of raw graphite on the resulting structural, morphological, optical and electrical properties of GO samples and their poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites are studied for the graphite particle distributions of <150, 45–75 and 25–45 μm. It is determined that particle size of raw graphite have an impact on oxidation degree, the chemical nature of oxygen functional groups on GO and it also affects the lateral size of obtained GO. PEDOT:PSS-GO composites are utilized as hole injection layer (HIL) in a solution process blue organic light emitting diode. Presence of GO caused negative differential resistance (NDR) and NDR intensity was decreased with the decrease in lateral size of GO, increase in the graphite particle size and carboxyl% of obtained GO. All PEDOT:PSS-GO composite based devices presented better performance than the bare PEDOT:PSS based reference device. The maximum luminous and external quantum efficiency values of the device that contain HIL of PEDOT:PSS-GO(150) were more than 40% and 50% higher than that of the reference, respectively. Two folds of increase in these performance values were able to be reached with the concentration optimization of GO/150 in PEDOT:PSS.
  • Article
    Citation - WoS: 114
    Citation - Scopus: 135
    Perspectives for Solid Biopolymer Electrolytes in Dye Sensitized Solar Cell and Battery Application
    (Elsevier Ltd., 2016) Singh, Rahul; Varlıklı, Canan; Bhattacharya, B.; Rhee, Hee-Woo; Varlıklı, Canan; Singh, Pramod K.; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Photovoltaic technologies represent one of the leading research areas of solar energy which is one of the most powerful renewable alternatives of fossil fuels. In a common photovoltaic application the batteries play a key role in storage of energy generated by solar panels. Although it will take time for dye sensitized solar cells (DSSCs) and batteries based on biopolymer electrolytes to take their places in the market, laboratory studies prove that they have a lot to offer. Most efficient DSSCs and batteries available in market are based on liquid electrolytes. The advantages of liquid electrolytes are having high conductivity and good electrode-electrolyte interface whereas, disadvantages like corrosion and evaporation limit their future sustainability. Biopolymer electrolytes are proposed as novel alternatives which may overcome the problems stated above. In this review, we focus on fabrication, working principle as well as up to date status of DSSCs and batteries using biopolymer electrolytes. The effects of structural and electrical properties of biopolymer based electrolytes on the solar energy conversion efficiencies of DSSCs and their compatibility with lithium or other salts in battery applications are summarized. Biopolymer electrolyte based DSSCs are categorized on the basis of types of additives and recent outcomes of author's laboratory studies on biopolymer electrolyte based DSSCs and batteries are also presented.