Mühendislik ve Doğa Bilimleri Fakültesi Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/1624

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Citation - WoS: 18
Citation - Scopus: 19
Development of Highly Luminescent Water-Insoluble Carbon Dots by Using Calix[4]pyrrole as the Carbon Precursor and Their Potential Application in Organic Solar Cells
(Amer Chemical Soc, 2022) Coşkun, Yağız; Ünlü, Fatma Yelda; Yılmaz, Tuğbahan; Türker, Yurdanur; Aydoğan, Abdullah; Kuş, Mahmut; Ünlü, Caner
Carbon dots (CDs) are carbon-based fluorescent nanomaterials that are of interest in different research areas due to their low cost production and low toxicity. Considering their unique photophysical properties, hydrophobic/amphiphilic CDs are powerful alternatives to metal-based quantum dots in LED and photovoltaic cell designs. On the other hand, CDs possess a considerably high amount of surface defects that give rise to two significant drawbacks: (1) causing decrease in quantum yield (QY), a crucial drawback that limits their utilization in LEDs, and (2) affecting the efficiency of charge transfer, a significant factor that limits the use of CDs in photovoltaic cells. In this study, we synthesized highly luminescent, water-insoluble, slightly amphiphilic CDs by using a macrocyclic compound, calix[4]pyrrole, for the first time in the literature. Calix[4]pyrrole-derived CDs (CP-DOTs) were highly luminescent with a QY of over 60% and size of around 4-10 nm with graphitic structure. The high quantum yield of CP-DOTs indicated that they had less amount of surface defects. Furthermore, CP-DOTs were used as an additive in the active layer of organic solar cells (OSC). The photovoltaic parameters of OSCs improved upon addition of CDs. Our results indicated that calix[4]pyrrole is an excellent carbon precursor to synthesize highly luminescent and water-insoluble carbon dots, and CDs derived from calix[4]pyrrole are excellent candidates to improve optoelectronic devices.
Citation - WoS: 10
Citation - Scopus: 11
Roll-To Vapor Deposition of Hydrophobic and Transparent Nano-Adhesive Polymeric Thin Films on Rigid and Flexible Substrates
(Amer Chemical Soc, 2022) Şakalak, Hüseyin; Yilmaz, Kurtuluş; Gürsoy, Mehmet; Karaman, Mustafa
This paper demonstrates the adhesive and hydro- Rool-to-roll phobic modifications of glass, poly(ethylene terephthalate), and iCVD bamboo fabric surfaces using the initiated chemical vapor deposition (iCVD) process. iCVD of functional thin films is an all-dry and low-temperature alternative to the conventional wet coating processes. The as-deposited film is a terpolymer in which ethylhexyl acrylate and acrylic acid units comprised the pressure-sensitive adhesive (PSA) part, while perfluorodecyl acrylate (PFDA) acted as the hydrophobic part due to its low surface energy fluorinated side groups. The PFDA composition in the iCVD terpolymer can be systematically varied by adjusting the initial gas feed fractions of monomers, as verified from FTIR and XPS analyses. The usage of the initiator tertbutyl peroxide during the depositions resulted in high deposition rates up to 80 nm/min at a filament temperature of 230 degrees C. The as-deposited films possessed high optical transparency with high shear and peel strength values. Depending on the chemical composition, the peel strength values were up to 0.5 N/25 mm on flexible PET substrates. After the coating, the highly porous bamboo surface not only became sticky due to the existence of the thin PSA layer on top but also the became near-superhydrophobic. The application of iCVD coating parameters to deposit hydrophobic PSA on moving large-area substrates under roll-to-roll deposition mode resulted in highly uniform coatings, which shows the potential of iCVD to be operated in industrial scales to functionalize the industrially important flexible substrates.
Citation - WoS: 6
Citation - Scopus: 6
Separation of Pimelic Acid Using Tri-N in Various Organic Solvents by Reactive Extraction: Equilibrium and Modeling
(Amer Chemical Soc, 2022) Zeidan, Hani; Yurdakul, Merve; Martı, Mustafa Esen
Separation of carboxylic acids from dilute aqueous solutions is a challenging problem, and reactive extraction has been examined as an attractive alternative for this process. This study aims to investigate the reactive extraction of pimelic acid (PA) using tri-n-octylamine (TOA) in 1-hexanol, 1-octanol, xylene, and n-hexane. The highest extraction efficiency (E (%)) and distribution coefficient (K-D) were obtained at pH 3, which is the unadjusted pH of the aqueous PA solution. Extractive efficiency varied inversely with temperature and initial PA concentration but increased with the increase in TOA amount. The highest E (%) and K-D values (98.5% and 67.2, respectively) were obtained with 1-hexanol at initial TOA and PA concentrations of 0.2700 and 0.0375 mol/kg, respectively. The process was modeled using multilinear regression, and the model closely correlated with experimental results for all organic solvents tested.

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