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Öğe Cycling Durability of Electrochromic W-Ti Oxide Thin Films: Optical Transmittance Data Signal Dual Degradation Modes(Electrochemical Soc Inc, 2020) Sorar, Idris; Granqvist, Claes G.; Niklasson, Gunnar A.Electrochemical degradation of electrochromic W oxide and W-Ti oxide thin films, prepared by reactive DC magnetron sputtering, was studied by voltammetric cycling in potential intervals from 1.5-4.0 to 2.0-4.0 V vs Li/Li+ in an electrolyte of lithium perchlorate in propylene carbonate. Cycling-dependent evolution of the upper and lower limits for the optical modulation range was critically dependent on potential interval. This phenomenon was analyzed through an extension of a previously formulated model for power-law dynamics; it was discovered that the upper and lower limits for the optical modulation range varied in distinctly different ways, and that only data acquired in the interval 2.0-4.0 V vs Li/Li+ could be reconciled with dispersive chemical kinetics. We thus find that our data on optical transmittance degradation lends strong support to the existence of dual degradation modes for electrochromism upon extended electrochemical cycling. This result is of great importance for the development of highly durable electrochromic devices such as smart windows for energy-efficient buildings. The present article is a sequel to a recent publication of ours [J. Electrochem. Soc., 166, H795 (2019)]. (c) 2020 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.Öğe Durability and rejuvenation of electrochromic tungsten oxide thin films in LiClO4-propylene carbonate viscous electrolyte: Effect of Ti doping of the film and polyethylene oxide addition to the electrolyte(Elsevier, 2023) Sorar, Idris; Atak, Gamze; Pehlivan, Ilknur Bayrak; Granqvist, Claes G.; Niklasson, Gunnar A.Tungsten oxide and titanium doped tungsten oxide thin films, deposited by sputtering, were immersed in a viscous electrolyte comprised of LiClO4 in propylene carbonate and 2.0 wt% of polyethylene oxide (PEO). Electrochromic properties of the films were investigated by electrochemical techniques and in situ transmittance measurements. Cyclic voltammetry data were taken in the voltage ranges 2.0-4.0 and 1.5-4.0 V vs Li/Li+ for up to 500 cycles. A potentiostatic rejuvenation treatment was then performed on the degraded electrochromic films, at 6.0 V for 20 h, which was subsequently followed by another cyclic voltammetry measurement. Titanium incorporation into tungsten oxide resulted in a small cyclic stability improvement in the 2.0-4.0-V range, whereas less pronounced effects were observed for cycling in the 1.5-4.0-V range. Combining the results of the present study with our previous work, we are able to assess the relative merits of titanium incorporation and PEO addition to the electrolyte for the durability of electrochromic tungsten oxide thin films. Titanium addition was found advantageous for electrochemical durability in the 2.0-4.0-V range, but no clear benefits of PEO in the electrolyte were seen. On the other hand, in the wider 1.5-4.0-V range, tungsten oxide exhibited better durability than titanium-containing films, and this was especially so after rejuvenation in the PEO-containing electrolyte.Öğe The effect of organic solvents on the optical and morphological properties of metallophthalocyanines containing 3,5-bis(2?,3?,4?,5?,6?-pentafluorobenzyloxy) benzyloxy groups(World Sci Publ Co Inc, 2019) Ozcesmeci, Mukaddes; Sorar, Idris; Hamuryudan, EsinThin films of metal phthalocyanines (M: Co, Zn, Ni) substituted with four 3,5-bis(2',3',4',5',6'-pentafluorobenzyloxy)benzyloxy groups have been prepared by the spin-coating technique. Optical properties and surface morphology of the thin films of metallophthalocyanines have been investigated as a function of organic solvents of acetone, chloroform, tetrahydrofuran, dimethylfonnamide and dimethylsulfoxide. Results show that optical properties and surface morphology of the prepared films depend on the type of organic solvent used.Öğe The effect of Zn metallophthalocyanine on the optical and structural properties of sol-gel spin coated TiO2 thin films(Natl Inst Optoelectronics, 2021) Sarigul, Hasan; Ozcesmeci, Ibrahim; Sorar, IdrisIn this study, TiO2, TiO2/ZnPc and ZnPc thin films were deposited on glass substrates by spin coating method and the effect of ZnPc doping concentration on the optical and structural properties of the films was investigated. A spectrophotometer in the 300-1100 nm wavelength range was used to measure the optical transmittance of thin films. UV-Vis studies showed that transmittance of the films decreased with the increasing concentration of ZnPc in the ranges corresponding to the B and Q band absorption regions, which are the characteristic peaks of phthalocyanines between 300-400 nm and 600-700 nm, respectively. Scanning electron microscopy (SEM) was used to characterize the surface morphology of thin films and they were observed to be homogeneously coated. X-ray measurements of annealed films showed an anatase-brookite mixed phase and it was found that crystal size decreased with increasing ZnPc concentration.Öğe Electrochromism in Ni Oxide Thin Films Made by Advanced Gas Deposition and Sputtering: A Comparative Study Demonstrating the Significance of Surface Effects(Electrochemical Soc Inc, 2020) Sorar, Idris; Welearegay, Tesfalem G.; Primetzhofer, Daniel; Osterlund, Lars; Granqvist, Claes G.; Niklasson, Gunnar A.Films of electrochromic Ni oxide, with thickness in the similar to 100-1000-nm range, were prepared by reactive advanced gas deposition (AGD) and, for comparison, also by reactive DC magnetron sputtering (MS). Voltammetric cycling was performed in an electrolyte of lithium perchlorate in propylene carbonate in the voltage range 2.0-4.1 V vs Li/Li+, and concurrent optical transmittance modulation was studied at a wavelength of 530 nm. For the thickest films, the optical modulation range was as large as similar to 54% and the maximum transmittance was similar to 82% for deposition by AGD, whereas the corresponding numbers were similar to 45% and similar to 87% for MS. Rutherford backscattering spectrometry together with measurements of film thickness demonstrated that the porosity of 400-500-nm-thick films made by AGD and MS were similar to 84% and similar to 45%, respectively. The charge exchange per mass unit was as high as 48-67 C g(-1) for samples made by AGD. The corresponding number was much lower for MS, namely 13-18 C g(-1). These results lend convincing support to the view that the electrochromism of Ni-oxide-based films in Li-ion-conducting electrolytes is dominated by surface effects. (C) 2020 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.Öğe Electrochromism of DC magnetron sputtered TiO2 thin films: Role of deposition parameters(Elsevier, 2013) Sorar, Idris; Pehlivan, Esat; Niklasson, Gunnar A.; Granqvist, Claes G.We performed a comprehensive study on the electrochromism in TiO2 thin films made by reactive DC magnetron sputtering and elucidated the roles of sputter gas pressure p, O-2/Ar gas ratio gamma and substrate temperature tau(s). Good mid-luminous optical modulation taken to be similar to 50% in similar to 200-nm-thick films was obtained under charge exchange in a Li+ electrolyte for p > 15 mTorr and tau(s) < 100 degrees C, whereas gamma was less important. The deposition rate dropped for increasing p, and hence p approximate to 15 mTorr was optimal. These films were X-ray amorphous and contained some water. The coloration efficiency eta was 25 cm(2)/C, which exceeds data on eta in most prior studies on sputter deposited TiO2 and verifies that such films can display the same values of eta as those of TiO2 films made by several chemical techniques. (C) 2013 Elsevier B.V. All rights reserved.Öğe Electrochromism of DC magnetron-sputtered TiO2: Role of film thickness(Elsevier Science Bv, 2014) Sorar, Idris; Pehlivan, Esat; Niklasson, Gunnar A.; Granqvist, Claes G.Titanium dioxide films were prepared by reactive DC magnetron sputtering and the role of the film thickness d on the electrochromism was analyzed for 100 < d < 400 nm. The best properties were obtained for the thickest films, which yielded a mid-luminous transmittance modulation of 58% and a corresponding coloration efficiency of 26.3 cm(2)/C. The films were amorphous according to X-ray diffraction measurements and showed traces of adsorbed water as revealed by infrared spectroscopy. (C) 2013 Elsevier B.V. All rights reserved.Öğe Electrochromism of W-In oxide thin films: Implications for cycling durability(Elsevier Science Sa, 2020) Sorar, Idris; Pehlivan, Ilknur Bayrak; Granqvist, Claes G.; Niklasson, Gunnar A.Electrochromic W oxide and W-In oxide thin films were prepared by dual-target reactive DC magnetron sputtering and were cycled voltammetrically in an electrolyte of lithium perchlorate in propylene carbonate. Film degradation was investigated for up to 500 cycles in the voltage ranges 1.5-4.0, 1.7-4.0 and 2.0-4.0 V vs. Li/Li+, and optical transmittance was recorded concurrently. Indium doping was found to be unambiguously detrimental to electrochromic cycling durability, which resolves an outstanding issue related to recently discovered unprecedented durability of potentiostatically pretreated W oxide films backed by In2O3:Sn and gives strong support in favor of beneficial effects of solid-electrolyte interfacial layers.Öğe Electrochromism of W-Ti Oxide Thin Films: Cycling Durability, Potentiostatic Rejuvenation, and Modelling of Electrochemical Degradation(Electrochemical Soc Inc, 2019) Sorar, Idris; Rojas-Gonzalez, Edgar A.; Pehlivan, Ilknur Bayrak; Granqvist, Claes G.; Niklasson, Gunnar A.Thin films of electrochromic W oxide and W-Ti oxide were prepared by reactive DC magnetron sputtering and were cycled voltammetrically in an electrolyte of lithium perchlorate in propylene carbonate. Film degradation was studied for up to 500 voltammetric cycles in voltage ranges between 1.5-4.0 and 2.0-4.0 V vs. Li/Li+. Optically and electrochemically degraded films were subjected to potentiostatic posttreatment at 6.0 V vs. Li/Li+ to achieve ion de-trapping and rejuvenation so that the films partly regained their original properties. Ti incorporation and potentiostatic posttreatment jointly yielded superior electrochromic properties provided the lower limit of the voltage range was above 1.6-1.7 V vs. Li/Li+. Degradation dynamics for as-deposited and rejuvenated thin films was modeled successfully by power-law kinetics; this analysis indicated coexistence of two degradation mechanisms, one based on dispersive chemical kinetics and operating universally and another, of unknown origin, rendered inactive by rejuvenation. The results of the present study are of large interest for the development of electrochromic devices with exceptional durability. (C) 2019 The Electrochemical Society.Öğe Investigation of Biodegradable Ternary Mg-Zn-La Magnesium Alloys(Amer Inst Physics, 2018) Ozarslan, Selma; Sevik, Huseyin; Sorar, IdrisIn this paper, the effect of Lanthanum (1, 2 and 4 wt.%) addition to biodegradable Mg-4Zn alloy and its influence on the microstructure and mechanical properties of the alloy were investigated. The alloys were produced under protective atmosphere by a cold chamber high pressure-die casting process. Microstructure analysis of the samples were carried out by scanning electron microscopy (SEM), an energy-dispersive spectrometer (EDS) and X-ray diffraction (XRD). X-ray difractometry revealed that the main phases are alpha-Mg and MgZn in the whole alloys. Also, the Mg17La2 phase was observed with addition of La. Hardness and tensile properties were examined to investigate the mechanical properties. Results showed that the yield strength and nanohardness of main alloy were improved from 40 % (100 MPa to 140 MPa), 24 % (from 1.04 GPa to 1.29 GPa) with addition of 4 wt.% La, respectively. However, elongation was decreased with increasing of La content.Öğe Investigation of Microstructural, Mechanical and Corrosion Properties of Biodegradable Mg-Sn-Y Alloys(Springer Int Publ Ag, 2024) Ozarslan, Selma; Sorar, Idris; Sevik, HuseyinIn this study, biodegradable magnesium alloys were produced using the high pressure die casting (HPDC) technique. Effects of Y addition on microstructure, mechanical properties and corrosion behaviors of as-cast Mg-4Sn-xY (x = 0, 1, 2, 4 wt.%) alloys are investigated. The surface morphology of the alloys was examined using field emission scanning electron microscopy (FE-SEM) and the microstructure was examined using energy dispersive spectroscopy (EDS), respectively. Tensile and hardness tests were carried out to examine the mechanical properties. Microstructural studies have shown that the addition of yttrium causes a reduction in the grain size of the alloy and the formation of Sn3Y5 and MgSnY intermetallic compounds with high melting temperature, as well as Mg2Sn intermetallic. While, the maximum tensile strength value is achieved with the addition of 1% yttrium by weight, the increase in yield strength, elongation percentage and hardness values continue with the addition of more yttrium. Corrosion tests have shown that the addition of yttrium to the Mg-Sn alloy increases the corrosion resistance of the alloys due to microstructural changes. The Mg-4Sn-4Y alloy is found to be a promising biodegradable magnesium alloy especially for orthopedic applications.Öğe Microstructure, mechanical and corrosion properties of novel Mg-Sn-Ce alloys produced by high pressure die casting(Elsevier, 2019) Ozarslan, Selma; Sevik, Huseyin; Sorar, IdrisThe aim of this study was to investigate the effect of adding 1, 2 and 4% wt of cerium on the microstructure, mechanical and corrosion properties of high pressure die casting (HPDC) Mg-4Sn alloys. Microstructure analyses of the alloys were carried out using X-Ray Diffraction (XRD) and Scanning Electron microscopy (SEM). The corrosion behaviors were determined with the potentiodynamic polarization and immersion tests in Hanks Balanced Salt Solution (HBSS), which is used as the artificial body fluid. The microstructural results showed that the addition of Ce to the main alloy creates new intermetallic phases (Ce5Sn4 and MgSnCe). In addition, Ce addition provided effectively the grain refinement of the alloys. While the hardness and yield strength of the Mg-4Sn alloy enhanced continuously with increasing Ce content, the tensile strength and elongation reached up to 2% wt. The corrosion resistance of the main alloy was improved by the addition of 1% wt of Ce. However, the Ce content, which is more than 1% wt decreased corrosion resistance.Öğe Optical and morphological properties and in silico studies on metallophthalocyanines containing pyridyloxy moieties(Elsevier, 2020) Sorar, Idris; Ozcesmeci, Ibrahim; Katirci, Ramazan; Gul, AhmetMetallophthalocyanines (M = zinc (II) and cobalt (II)) containing four 4-pyridyloxy -terminal groups were prepared by cyclotetramerization of 4-(4-pyridyloxy)phthalonitrile. The optimized geometry, electronic properties (chemical hardness, electron affinity, electronegativity), linear and nonlinear optical features of the phthalocyanine derivatives were investigated using density functional theory (DFT). The energy of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were calculated. The excitation features of electrons in the ultraviolet-visible (UV) region were computed with time-dependent density functional theory (TD-DFT). Thin films of these metallophthalocyanines which have low solubility in organic solvents have been prepared by spin coating after solution preparation by both magnetic stirring and ultrasonic treatment. Results showed that ultrasonic treatment increased the solubility of the compounds and better thin films were obtained. (C) 2020 Elsevier B.V. All rights reserved.Öğe Optical and Morphological Properties of New Metallophthalocyanines with Hydroxyethylsulfanyl Substituents(Maik Nauka/Interperiodica/Springer, 2019) Sorar, Idris; Ozcevneei, Ibrahim; Gul, AhmetMetallophthalocyanine complexes (M = Pd, FeCl, VO, or MnCl) bearing four hydroxyl-terminated aliphatic groups were prepared by cyclotetramerization 4-(hydroxyethylsulfanyl)phthalonitrile. Aggregation tendencies of these phthalocyanines were investigated in varying concentrations from 4 x 10(-5) to 8 x 10(-6) M in DMF. Spin coating method was used to prepare thin films of metallophthalocyanines substituted with four hydroxyethylsulfanyl groups. The optical properties of the films were investigated as a function of the different metal ions in the inner core, with the transmittance spectrum measured at a wavelength range of 200-1000 nm. The results show that different metal ions in the inner core clearly change the transmittance values of the thin films of metallophthalocyanine. Morphological results also show that surface of the metallophthalocyanines has changed considerably according to the nature of the metal ion.Öğe Optical studies on phthalocyanines substituted with phenylazonaphthoxy groups(Taylor & Francis Ltd, 2016) Ozcesmeci, Ibrahim; Sorar, Idris; Gul, AhmetThe synthesis and characterization of peripherally ({1-[(Z or E)-phenylazo]-2-naphthyl} oxy) tetra-substituted metal-free and metallo (Zn(II), Co(II) and Cu(II)) phthalocyanines are described in this study. Aggregation properties of these compounds were investigated in the concentration range of 20-1M in tetrahydrofuran. Spectroscopic and photophysical properties of these phthalocyanines have been investigated in tetrahydrofuran. Thin films of metallophthalocyanines were prepared by spin coating technique. Results show that transmittance values of the films change with respect to the metal ions in the visible and Q absorptions regions. Films were also annealed at 100, 200 and 300 degrees C and their optical properties were investigated as a function of annealing temperature. The spectrophotometric measurements of transmittance spectra were carried out in the wavelength range 200-1000nm. Results showed that transmittance values of ZnPc thin films were increased as a result of heat treatment.Öğe Potentiostatic rejuvenation of electrochromic WO3 thin films: Exploring the effect of polyethylene oxide in LiClO4-Propylene carbonate electrolytes(Elsevier, 2020) Sorar, Idris; Pehlivan, Ilknur Bayrak; Bohlin, Jan; Granqvist, Claes G.; Niklasson, Gunnar A.Thin films of electrochromic (EC) W oxide were prepared by reactive DC magnetron sputtering and were immersed in electrolytes of LiClO4 in propylene carbonate with 0.5-3.0 wt% of added polyethylene oxide (PEO). Charge density and optical modulation range were found to diminish monotonically upon prolonged voltammetric cycling with concurrent optical transmittance measurements for up to 500 and 200 cycles in the voltage ranges 2.0-4.0 and 1.5-4.0 V vs. Li/Li+, respectively. Rejuvenation of the degraded EC films was then accomplished by potentiostatic treatment at 6.0 V vs. Li/Li+ for 20 h and has been ascribed to expulsion of trapped Li ions. Importantly, degradation subsequent to rejuvenation was found to progress at a significantly lowered pace than for as-deposited films in proportion with the amount of PEO especially for harsh voltammetric cycling in the voltage range 1.5-4.0 V vs. Li/Li+. The results of this explorative study are of considerable value for the development of highly durable EC devices such as polymer-laminated smart glazing for energy efficient buildings with excellent indoor comfort.Öğe Spectroscopic, electrochemical and optical properties of non-peripherally (2,2-dimethyl-1,3-dioxolan-4-yl)methoxy groups substituted metal-free and metallophthalocyanines(Elsevier, 2021) Tagman, Irem; Ozcesmeci, Mukaddes; Gumrukcu, Selin; Sorar, IdrisMetal-free and metallophthalocyanine complexes (M = 2H, InCl, or MnCl) containing (2,2-dimethyl-1,3dioxolan-4-yl)methoxy groups were synthesized and characterized. The electrochemical properties of the phthalocyanine complexes were investigated by cyclic and square wave voltammetry. Metal-free and indium phthalocyanines give ring-based oxidation and reduction processes, while manganese phthalocyanine gives both metal and ring-based redox processes. Thin films of phthalocyanines were prepared by spin coating technique. The films were investigated as a function of the different metal ions in the inner core, with the transmittance spectrum measured at a wavelength range of 20 0-10 0 0 nm. The results show that type of metal ions in the phthalocyanine core clearly change the transmittance values of the thin films of phthalocyanine complexes. Surface morphologies of the films were characterized by scanning electron microscopy. It has been observed that metal-free films form a more continuous and non-porous structure, while InPc and MnPc films have a porous surface. (c) 2021 Elsevier B.V. All rights reserved.Öğe Synthesis, characterization, and optical studies of pentoxy-substituted tetrakis(pentafluorobenzyloxy)phthalocyanines(Taylor & Francis Ltd, 2018) Ozcesmeci, Mukaddes; Sorar, Idris; Ozcesmeci, Ibrahim; Hamuryudan, EsinThe synthesis and characterization of peripherally 2,3,5,6-tetrafluoro-4-pentoxy-benzyloxy-substituted metal-free and metallo (Zn(II) and Co(II)) phthalocyanines are described in this study. Aggregation properties of these phthalocyanines were studied in the concentration range of 1x10(-5)-1x10(-6)M in tetrahydrofuran. Thin films of phthalocyanines were prepared by spin-coating technique. The spectrophotometric measurements of transmittance spectra were carried out in the wavelength range of 200-1000nm. Optical band gaps of phthalocyanine thin films were also calculated. Surface morphologies and thickness of the films were examined by Scanning Electron Microscopy. Results show that film thickness can be changed significantly depending on the type of metal in the phthalocyanine.Öğe Synthesis, optical and structural studies of tetrakis[4-(2?,3?,4?,5?,6?-pentafluorobenzyloxy)benzyloxy]-substituted metallo-phthalocyanines(Elsevier Science Sa, 2012) Ozcesmeci, Mukaddes; Sorar, Idris; Hamuryudan, EsinMetallo-phthalocyanines substituted with four pentafluorobenzyloxy units through benzyloxy-bridges were synthesized from a new phthalonitrile derivative and characterized by spectroscopic methods. The aggregation behaviour of these compounds were investigated in different concentrations of tetrahydrofuran. The effect of solvents on absorption spectra were studied in various organic solvents. Thin films of metallo-phthalocyanines were obtained by using spin coating on 2947 Corning glass substrates. Optical transmittance of thin films was measured using a spectrophotometer in the wavelength range of 300-1000 nm. Results showed that transmittance decreases with the increasing concentration in the ranges corresponding to B and Q absorptions, but the films can still be proposed as optical windows between these regions (similar to 400-600 nm) due to very low absorbances. The surface morphology of the thin films were investigated by atomic force microscopy. The phthalocyanine molecules grow in stacks of rows rather in the zig-zag or parallel. (C) 2011 Elsevier B.V. All rights reserved.Öğe Thin films of fluorinated groups substituted metallophthalocyanines as an optical material(Elsevier Science Bv, 2017) Ozcesmeci, Mukaddes; Ozcesmeci, Ibrahim; Sorar, Idris; Hamuryudan, EsinIn this study, we report the synthesis and characterization of palladium(II)phthalociyanine including fluoro-4'-hexylthio-benzyloxy groups for the first time. The optical properties of a series of pentafluorobenzyloxy and tetrafluoro-4'-hexylthio-benzyloxy metallo-phthalocyanines were studied. Thin films of these compounds were obtained by using spin coating technique. Optical transmittance of thin films was measured using a spectrophotometer in the wavelength range of 200-1000 nm. Optical band gaps of thin films were also calculated. In addition, surface morphologies and thickness of the films were investigated by Scanning Electron Microscopy. Results showed that the transmittance, band gap and morphology of the films are highly dependent on the metals and substituted groups of the phthalocyanines. (C) 2017 Elsevier B.V. All rights reserved.
