Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 8Citation - Scopus: 8Writing Chemical Patterns Using Electrospun Fibers as Nanoscale Inkpots for Directed Assembly of Colloidal Nanocrystals(Royal Soc Chemistry, 2020) Kiremitler, N. Burak; Torun, Ilker; Altintas, Yemliha; Patarroyo, Javier; Demir, Hilmi Volkan; Puntes, Victor F.; Onses, M. SerdarApplications that range from electronics to biotechnology will greatly benefit from low-cost, scalable and multiplex fabrication of spatially defined arrays of colloidal inorganic nanocrystals. In this work, we present a novel additive patterning approach based on the use of electrospun nanofibers (NFs) as inkpots for end-functional polymers. The localized grafting of end-functional polymers from spatially defined nanofibers results in covalently bound chemical patterns. The main factors that determine the width of the nanopatterns are the diameter of the NF and the extent of spreading during the thermal annealing process. Lowering the surface energy of the substrates via silanization and a proper choice of the grafting conditions enable the fabrication of nanoscale patterns over centimeter length scales. The fabricated patterns of end-grafted polymers serve as the templates for spatially defined assembly of colloidal metal and metal oxide nanocrystals of varying sizes (15 to 100 nm), shapes (spherical, cube, rod), and compositions (Au, Ag, Pt, TiO2), as well as semiconductor quantum dots, including the assembly of semiconductor nanoplatelets.Article Citation - WoS: 15Citation - Scopus: 14Understanding Plasmon Coupling in Nanoparticle Dimers Using Molecular Orbitals and Configuration Interaction(Royal Soc Chemistry, 2019) Alkan, Fahri; Aikens, Christine M.We perform a theoretical investigation of the electronic structure and optical properties of atomic nanowire and nanorod dimers using DFT and TDDFT. In both systems at separation distances larger than 0.75 nm, optical spectra show a single feature that resembles the bonding dipole plasmon (BDP) mode. A configuration interaction (CI) analysis shows that the BDP mode arises from constructive coupling of transitions, whereas the destructive coupling does not produce significant oscillator strength for such separation distances. At shorter separation distances, both constructive and destructive coupling produce oscillator strength due to wave-function overlap, which results in multiple features in the calculated spectra. Our analysis shows that a charge-transfer plasmon (CTP) mode arises from destructive coupling of transitions, whereas the BDP results from constructive coupling of the same transitions at shorter separation distances. Furthermore, the coupling elements between these transitions are shown to depend heavily on the amount of exact Hartree-Fock exchange (HFX) in the functional, which affects the splitting of CTP and BDP modes. With 50% HFX or more, the CTP and BDP modes mainly merge into a single feature in the spectra. These findings suggest that the effects of exact exchange must be assessed during the prediction of CTP modes in plasmonic systems.Article Citation - WoS: 16Citation - Scopus: 16The Hansen Solubility Approach Towards Green Solvent Processing: N-Channel Organic Field-Effect Transistors Under Ambient Conditions(Royal Soc Chemistry, 2024) Deneme, Ibrahim; Yildiz, Tevhide Ayca; Kayaci, Nilgun; Usta, HakanThe adoption of green solvents is of utmost importance for the solution-based fabrication of semiconductor thin films and for the commercialization of (opto)electronic devices, especially in response to evolving regulatory mandates for handling organic materials. Despite the increasing interest in this area, the scarcity of green solvent-processed n-channel OFETs, especially functioning under ambient conditions, highlights the need for further research. In this study, we demonstrated the Hansen solubility approach to study the solubility behavior of an ambient-stable n-type semiconductor, 2,2' -(2,8-bis(3-dodecylthiophen-2-yl)indeno[1,2-b]fluorene-6,12-diylidene)dimalononitrile (beta,beta'-C-12-TIFDMT), and to analyze potential green solvents for thin-film processing. The Hansen solubility parameters were determined to be delta(D) = 20.8 MPa1/2, delta(P) = 5.8 MPa1/2, and delta(H) = 5.5 MPa1/2 with a radius (R-0) of 8.3 MPa1/2. A green solvent screening analysis based on the minimal distance constraint and quantitative sustainability score identified ethoxybenzene, anisole, 2-methylanisole, and 2-methyltetrahydrofuran as suitable green solvents (R-a's = 5.17-7.93 MPa1/2 < R-0). A strong thermodynamic correlation was identified between the solubility and the semiconductor-solvent distance in the 3D Hansen solubility space, in which the maximum solubility limit could be estimated with the enthalpy of fusion (Delta H-fus) and melting temperature (T-mp) of the semiconductor. To the best of our knowledge, this relationship between the maximum solubility limit and thermal properties has been established for the first time for organic semiconductors. Bottom-gate/top-contact OFETs fabricated by spin-coating the semiconductor green solutions exhibited mu es reaching similar to 0.2 cm(2) V-1 s(-1) (I-on/I-off similar to 10(6)-10(7) and V-on similar to 0-5 V) under ambient conditions. This device performance, to our knowledge, is the highest reported for an ambient-stable green solvent-processed n-channel OFET. Our HSP-based rational approach and unique findings presented in this study can shed critical light on how green solvents can be efficiently incorporated in solution processing in organic (opto)electronics, and whether ambient-stable n-type semiconductors can continue to play an important role in green OFETs.Article Citation - WoS: 22Citation - Scopus: 24The Design and Fabrication of Supramolecular Semiconductor Nanowires Formed by Benzothienobenzothiophene (BTBT)-Conjugated Peptides(Royal Soc Chemistry, 2018) Khalily, Mohammad Aref; Usta, Hakan; Ozdemir, Mehmet; Bakan, Gokhan; Dikecoglu, F. Begum; Edwards-Gayle, Charlotte; Guler, Mustafa O.pi-Conjugated small molecules based on a [1]benzothieno[3,2-b]benzothiophene (BTBT) unit are of great research interest in the development of solution-processable semiconducting materials owing to their excellent charge-transport characteristics. However, the BTBT -core has yet to be demonstrated in the form of electro-active one-dimensional (1D) nanowires that are self-assembled in aqueous media for potential use in bioelectronics and tissue engineering. Here we report the design, synthesis, and self-assembly of benzothienobenzothiophene (BTBT)-peptide conjugates, the BTBT-peptide (BTBT-C-3-COHN-Ahx-VVAGKK-Am) and the C-8-BTBT-peptide (C-8-BTBT-C-3-COHN-Ahx-VVAGKK-Am), as -sheet forming amphiphilic molecules, which self-assemble into highly uniform nanofibers in water with diameters of 11-13(+/- 1) nm and micron-size lengths. Spectroscopic characterization studies demonstrate the J-type - interactions among the BTBT molecules within the hydrophobic core of the self-assembled nanofibers yielding an electrical conductivity as high as 6.0 x 10(-6) S cm(-1). The BTBT -core is demonstrated, for the first time, in the formation of self-assembled peptide 1D nanostructures in aqueous media for potential use in tissue engineering, bioelectronics and (opto)electronics. The conductivity achieved here is one of the highest reported to date in a non-doped state.Article Sustainable Next-Generation Color Converters From P. Harmala Seed Extracts for Solid-State Lighting(Royal Soc Chemistry, 2024) Erdem, Talha; Orenc, Ali; Akcan, Dilber; Duman, Fatih; Soran-Erdem, ZelihaTraditional solid-state lighting heavily relies on color converters, which often have a significant environmental footprint. As an alternative, natural materials such as plant extracts could be employed if their low quantum yields (QYs) in liquid and solid states were higher. With this motivation, here, we investigate the optical properties of aqueous P. harmala extract, develop efficient color-converting solids through a cost-effective and environmentally friendly method, and integrate them with light-emitting diodes (LEDs). To achieve high-efficiency solid hosts for P. harmala-based fluorophores, we optically and structurally compare two crystalline and two cellulose-based platforms. Structural analyses reveal that sucrose crystals, cellulose-based cotton, and paper platforms enable a relatively homogeneous distribution of fluorophores compared to KCl crystals. Optical characterization demonstrates that the extracted solution and the extract-embedded paper possess QYs of 75.6% and 44.7%, respectively, whereas the QYs of the cotton, sucrose, and KCl crystals remain below 10%. We demonstrated that the paper host with the highest efficiency causes a blueshift in the P. harmala fluorescence, whereas the cotton host induces a redshift. We attribute this to the passivation of nonradiative transitions related to the structure of the hosts. Subsequently, as a proof-of-concept demonstration, we integrate the as-prepared efficient solids of P. harmala for the first time with a light-emitting diode (LED) chip to produce a color-converting LED. The resulting blue-emitting LED achieves a luminous efficiency of 21.9 lm W-elect(-1) with CIE color coordinates of (0.139, 0.070). These findings mark a significant step toward the utilization of plant-based fluorescent biomolecules in solid-state lighting, offering promising environmentally friendly organic color conversion solutions for future lighting applications.Article Citation - WoS: 25Citation - Scopus: 27Selective Removal of Cationic Micro-Pollutants Using Disulfide-Linked Network Structures(Royal Soc Chemistry, 2017) Atas, Mehmet Sahin; Dursun, Sami; Akyildiz, Hasan; Citir, Murat; Yavuz, Cafer T.; Yavuz, Mustafa SelmanMicropollutants are found in all water sources, even after thorough treatments that include membrane filtration. New ones emerge as complex molecules are continuously produced and discarded after used. Treatment methods and sorbent designs are mainly based on non-specific interactions and, therefore, have been elusive. Here, we developed swellable covalent organic polymers (COP) with great affinity towards micropollutants, such as textile industry dyes. Surprisingly, only cationic dyes in aqueous solution were selectively and completely removed. Studies of the COPs surfaces led to a gating capture, where negatively charged layer attracts cationic dyes and moves them inside the swollen gel through diffusive and hydrophobic interaction of the hydrocarbon fragments. Despite its larger molecular size, crystal violet has been taken the most, 13.4 mg g(-1), surpassing all competing sorbents. The maximum adsorption capacity increased from 12.4 to 14.6 mg and from 8.9 to 11.4 mg when the temperature of dye solution was increased from 20 to 70 degrees C. The results indicated that disulfide-linked COPs are attractive candidates for selectively eliminating cationic dyes from industrial wastewater due to exceptional swelling behaviour, low-cost and easy synthesis.Article Citation - WoS: 12Citation - Scopus: 12External Complexation of Bodipys by Cb[7] Improves In-Cell Fluorescence Imaging(Royal Soc Chemistry, 2022) Ayhan, Mehmet Menaf; Ozcan, Emrah; Alkan, Fahri; Cetin, Metin; Un, Ilker; Bardelang, David; Cosut, BonyeminOrganic luminescent compounds with high emission properties play a crucial role in fluorescence labelling and optoelectronic devices. In this work, we prepared three water soluble BODIPY derivatives (B-4, B-5, and B-6) which are weakly fluorescent due to non-radiative relaxation pathways (charge transfer: CT or heavy atom effect). However, CB[7] significantly improves BODIPY fluorescence by similar to 10 fold for B-4, and by similar to 3 fold for B-5. The (TD)DFT analyses suggest that for B-4 and B-5, the CT state is blue-shifted as a result of the external binding of CB[7] near the pyridinium groups. This effect favoured a radiative decay through a locally-excited (LE) pi ->pi* transition state of BODIPYs resulting in a CB[7]-induced emission increase in solution (and in the solid state), without compromising singlet-to-triplet intersystem crossing (ISC). The improved emission of the BODIPY center dot CB[7] complexes was used for the fluorescence imaging of U87 cells illustrating the relevance of this approach. These results suggest that BODIPY center dot CB[7] complexes could be used as theragnostic agents by combining fluorescence imaging and treatment by photodynamic therapy.Article Citation - WoS: 26Citation - Scopus: 27A Simple Approach to Prepare Self-Assembled, Nacre-Inspired Clay/Polymer Nanocomposites(Royal Soc Chemistry, 2020) Xu, P.; Erdem, T.; Eiser, E.Inspired by the relationship between the well-ordered architecture of aragonite crystals and biopolymers found in natural nacre, we present a facile strategy to construct large-scale organic/inorganic nacre-mimetics with hierarchical structureviaa water-evaporation driven self-assembly process. We connect LAPONITE (R)-nanoclay platelets with each other using carboxymethyl cellulose, a cellulose derivative, thus creating thin, flexible films with a local brick-and-mortar architecture. The dried films show a pronounced resistance against tensile forces allowing for stronger thin films than nacre. In terms of functionalities, we report excellent glass-like transparency along with exceptional shape-persistent flame shielding. We also demonstrate that through metal ion-coordination we can further strengthen the interactions between the polymers and the nanoclays, and thus enhanced mechanical, and thermal properties as well as resistance against swelling and dissolution in aqueous environments. We believe that our simple pathway to fabricate such versatile polymer/clay nanocomposites can open avenues for inexpensive production of environmentally friendly, biomimetic materials in aerospace, wearable electrical devices, and in the food packaging industry.Article Citation - WoS: 39Citation - Scopus: 37A Dopant-Free 2,7-Dioctyl[1]Benzothieno[3,2 (C8-BTBT) Hole Transporting Layer for Highly Stable Perovskite Solar Cells With Efficiency Over 22%(Royal Soc Chemistry, 2022) Kaya, Ismail Cihan; Ozdemir, Resul; Usta, Hakan; Sonmezoglu, SavasIn this study, for the first time, n-i-p PSCs were fabricated using dopant-free 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) as the solution-processed hole transporting layer (HTL). The power conversion efficiency (PCE) of the optimized device with the C8-BTBT film that favored edge-on molecular alignment was 22.45% with negligible hysteresis. A thinner dopant-free C8-BTBT HTL effectively protected the perovskite layer from moisture resulting in better shelf-life stability for un-encapsulated PSCs, which maintained >80% of its initial PCE (after a period of 120 days) at a relative humidity level of 40-45%. In addition, the C8-BTBT-based PSCs kept their high performance with no obvious PCE loss at 60 degrees C for 20 days in the ambient atmosphere and retained 82% of their initial PCE at 85 degrees C for 10 days. Overall, our findings revealed that a thin solution-processed C8-BTBT HTL plays a critical role not only in hole extraction and transport but also in greatly improving the ambient and thermal stability of n-i-p PSCs.