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Charge transfer through amino groups-small molecules interface improving the performance of electroluminescent devices
(Elsevier Science Bv, 2016) Havare, Ali Kemal; Can, Mustafa; Tozlu, Cem; Kus, Mahmut; Okur, Salih; Demic, Serafettin; Demirak, Kadir; Kurt, Mustafa; Icli, Siddik
A carboxylic group functioned charge transporting was synthesized and self-assembled on an indium tin oxide (ITO) anode. A typical electroluminescent device [modified ITO/TPD (50 nm)/Alq(3) (60 nm)/LiF (2 nm)/(120 nm)] was fabricated to investigate the effect of the amino groups-small molecules interface on the characteristics of the device. The increase in the surface work function of ITO is expected to facilitate the hole injection from the ITO anode to the Hole Transport Layer (HTL) in electroluminescence. The modified electroluminescent device could endure a higher current and showed a much higher luminance than the nonmodified one. For the produced electroluminescent devices, the I-V characteristics, optical characterization and quantum yields were performed. The external quantum efficiency of the modified electroluminescent device is improved as the result of the presence of the amino groups-small molecules interface. (C) 2016 Elsevier B.V. All rights reserved.
Dye sensitized solar cells based on titanium dioxide nanoparticles synthesized by flame spray pyrolysis and hydrothermal sol-gel methods: a comparative study on photovoltaic performances
(Elsevier, 2020) Aboulouard, Abdelkhalk; Gultekin, Burak; Can, Mustafa; Erol, Mustafa; Jouaiti, Ahmed; Elhadadi, Benachir; Demic, Serafettin
Synthesis methods, shape and size of the nanocrystalline titanium dioxide (TiO2) are very crucial parameters for the power conversion efficiency of dye sensitized solar cells. in this article, nanoparticles of TiO2 powders have been synthesized via flame spray pyrolysis and hydrothermal sol-gel methods. These powders have been characterized by X-ray diffraction and scanning electron microscopy. in particular, the photovoltaic performances of the dye sensitized solar cells based on TiO2 synthesized by flame spray pyrolysis and hydrothermal sol-gel method have been compared. A commercial dye, N719 and a platinum doped counter electrode have been used for fabricating cells. Furthermore, a standard dye sensitized solar cell device has been fabricated by using a commercial Titania electrode in order to use as a reference cell. As a result, power conversion efficiencies of solar cells (under standard conditions, AM 1.5 G, 100 mW cm(-2)) have been calculated as 2.44, 3.94, and 7.67 % with TiO2 synthesized via flame spray pyrolysis method, hydrothermal sol-gel method and reference Titania electrode, respectively. (C) 2019 the Authors. Published by Elsevier B.V.
Effect of a pi-bridging unit in triphenylamine-benzothiadiazole based donor acceptor chromophores for dye-sensitized solar cells
(Pergamon-Elsevier Science Ltd, 2014) Yigit, Mesude Zeliha; Bilgili, Hakan; Sefer, Emre; Demic, Serafettin; Zafer, Ceylan; Can, Mustafa; Koyuncu, Sermet
Two new metal free sensitizers based on triphenylamine-benzothiadiazole were synthesized and used in dye sensitized solar cells (DSSCs). Electrochemical and optical properties of the dyes were studied by cyclic voltammetry, UV-vis absorption and fluorescence spectroscopy. A red shift was observed by the attachment of a thiophene (MZ-259) instead of a phenylene (MZ-255) bridge. The reverse effect was observed in the electrochemical properties because of the more electron-donating thiophene incorporated into the cyanoacrylic acid as an anchoring-acceptor unit in this system resulted in a higher LUMO level. The charge distribution of the dyes was also proved by DFT calculations using the Spartan10 program with the parameters of B3LYP and 6-31G** basis set. Finally the photovoltaic performances were investigated under standard AM 1.5 illumination with a power of 100 mW/cm(2) using an ionic liquid based electrolyte. The power conversion efficiencies, eta, were increased from 3.16% to 3.81% by using thiophene instead of phenylene as a pi-bridge unit. (C) 2014 Elsevier Ltd. All rights reserved.
Effect of TiO2 modification with amino-based self-assembled monolayer on inverted organic solar cell
(Elsevier Science Bv, 2017) Tozlu, Cem; Mutlu, Adem; Can, Mustafa; Havare, Ali Kemal; Demic, Serafettin; Icli, Siddik
The effects of surface modification of titanium dioxide (TiO2) on the performance of inverted type organic solar cells (i-OSCs) was investigated in this study. A series of benzoic acid derivatized self-assembled monolayer (SAM) molecules of 4'-[(hexyloxy) phenyl] amino-3,5-biphenyl dicarboxylic acid (CT17) and 4'-[1-naphthyl (phenyl) amino] biphenyl-4-carboxylic acid (CT19) were utilized to modify the interface between TiO2 buffer layer and poly-3 hexylthiophene (P3HT):[ 6,6]-phenyl C-61 butyric acid methyl ester (PC61BM) active layer having the device structure of ITO/TiO2/SAM/P3HT:PC61BM/MoO3/Ag. The work function and surface wetting properties of TiO2 buffer layer served as electron transporting layer between ITO and PC61BM active layer were tuned by SAM method. The solar cell of the SAM modified devices exhibited better performance. The power conversion efficiency (PCE) of i-OSCs devices with bare TiO2 electrodes enhanced from 2.00% to 2.21% and 2.43% with CT17 and CT19 treated TiO2 electrodes, respectively. The open circuit voltage (V-oc) of the SAM treated TiO2 devices reached to 0.60 V and 0.61 V, respectively, while the V-oc of untreated TiO2 was 0.57 V. The water contact angle of i-OSCs with CT17 and CT19 SAMs was also higher than the value of the unmodified TiO2 electrode. These results show that inserting a monolayer at the interface between organic and inorganic layers is an useful alternative method to improve the performance of i-OSCs. (C) 2017 Elsevier B.V. All rights reserved.
Electrical properties of SAM-modified ITO surface using aromatic small molecules with double bond carboxylic acid groups for OLED applications
(Elsevier Science Bv, 2014) Can, Mustafa; Havare, Ali Kemal; Aydin, Hasan; Yagmurcukardes, Nesli; Demic, Serafettin; Icli, Siddik; Okur, Salih
5-[(3-Methylphenyl)(phenyl)amino]isophthalic acid (5-MePIFA) and 5-(diphenyl)amino]Isophthalic acid (5-DPIFA) organic molecules were synthesized to form self-assembled monolayer on indium tin oxide (ITO) anode to enhance hole transport from ITO to organic hole transport layers such as TPD. The modified surface was characterized by scanning tunneling microscopy (STM). The change in the surface potential was measured by Kelvin probe force microscopy (KPFM). Our Kelvin probe force microscopy (KPFM) measurements showed that the surface potentials increased more than 100 mV with reference to bare indium tin-oxide. The results show that the threshold voltage on OLEDs with modified ITO is lowered significantly compared to OLEDs with unmodified ITO. The hole mobility of TPD has been estimated using space-charge-limited current measurements (SCLC). (C) 2014 Elsevier B.V. All rights reserved.
Electrochemical and optical properties of biphenyl bridged-dicarbazole oligomer films: Electropolymerization and electrochromism
(Pergamon-Elsevier Science Ltd, 2009) Koyuncu, Sermet; Gultekin, Burak; Zafer, Ceylan; Bilgili, Hakan; Can, Mustafa; Demic, Serafettin; Kaya, Ismet; Icli, Siddik
4,4'-Di(N-carbazoyl)biphenyl monomer (CBP) was synthesized and coated onto ITO-glass surface by electrochemical oxidative polymerization. Its CV shows two distinct one-electron and stepwise oxidation processes occurred at 1.29 and 1.61 V. By using this property, the monomer was electrochemically polymerized separately at these oxidation states and thus, two different oligomer films were obtained afterwards. Their spectro-electrochemical and electrochromic properties were also investigated. Switching ability of the oligomers was evaluated by kinetic studies upon measuring the percent transmittance (%T) at their maximum contrast point, indicating that these oligomers were found to be suitable material for electrochromic devices. (C) 2009 Elsevier Ltd. All rights reserved.
Electrochemical and optical properties of biphenyl bridged-dicarbazole oligomer films: Electropolymerization and electrochromism
(Pergamon-Elsevier Science Ltd, 2009) Koyuncu, Sermet; Gultekin, Burak; Zafer, Ceylan; Bilgili, Hakan; Can, Mustafa; Demic, Serafettin; Kaya, Ismet; Icli, Siddik
4,4'-Di(N-carbazoyl)biphenyl monomer (CBP) was synthesized and coated onto ITO-glass surface by electrochemical oxidative polymerization. Its CV shows two distinct one-electron and stepwise oxidation processes occurred at 1.29 and 1.61 V. By using this property, the monomer was electrochemically polymerized separately at these oxidation states and thus, two different oligomer films were obtained afterwards. Their spectro-electrochemical and electrochromic properties were also investigated. Switching ability of the oligomers was evaluated by kinetic studies upon measuring the percent transmittance (%T) at their maximum contrast point, indicating that these oligomers were found to be suitable material for electrochromic devices. (C) 2009 Elsevier Ltd. All rights reserved.
Electrochemical and optical properties of novel donor-acceptor thiophene-perylene-thiophene polymers
(John Wiley & Sons Inc, 2008) Koyuncu, Sermet; Kus, Mahmut; Demic, Serafettin; Kaya, Ismet; Ozdemir, Eyup; Icli, Siddik
In this study, donor-acceptor type thiophene-perylene-thiophene monomers were synthesized and polymerized by both oxidative polymerization using FeCl3 as catalyst and the electrochemical process. UV-vis, FTIR, H-1 NMR, and elemental analysis techniques were used for structural characterization. Thermal behaviors of these compounds were determined by using TGA system. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels and electrochemical and optical band gap values were calculated by using the results of cyclic voltammetry and UV-vis measurements, respectively. The number-average molecular weight (M-n), weight-average molecular weight (M-n), and polydispersity index (PDI) values of synthesized polymers were determined by size exclusion chromatography. Conductivity measurements of these polymers were carried out by electrometer by using a four-point probe technique. The conductivity was observed to be increased by iodine doping. (C) 2008 Wiley Periodicals, Inc.
Electrochromic and electroluminescent devices based on a novel branched quasi-dendric fluorene-carbazole-2,5-bis(2-thienyl)-1H-pyrrole system
(Royal Soc Chemistry, 2011) Koyuncu, Sermet; Usluer, Ozlem; Can, Mustafa; Demic, Serafettin; Icli, Siddik; Sariciftci, Niyazi Serdar
We report here the synthesis of a novel branched quasi-dendric system, 9,9'-(9,9'-dihexylfluorene-2,7-diyl)bis[3,6-bis(2,5-bis(2-thienyl) pyrrol-1-yl)carbazole], (FCSNS), in four steps, followed by coating onto an ITO-coated glass surface by an electropolymerization process to give a very stable cross-linked polymeric film (poly-FCSNS). The yellowish-green color of this film in its neutral state changed reversibly to black upon oxidation. An electrochromic device, assembled in the sandwich configuration [ITO/anodically coloring polymer (poly-FCSNS)//gel electrolyte//cathodically coloring polymer/(PEDOT)/ITO], exhibited a relatively short response time (about 1 s), a high redox stability, and a high coloration efficiency (1624 cm(2) C-1). In addition to electrochromic studies, organic light-emitting diode (OLED) work was also carried out using FCSNS. A multilayer OLED having a configuration of ITO/PEDOT:PSS/FCSNS/Alq(3)/LiF : Al was fabricated, and it showed a turn-on voltage of approximately 6 V and exhibited a bright green emission with a luminance of 3700 cd m(-2). The maximum luminous efficiency was found to be 2.0 cd A(-1) at 14 V and 11.75 mA cm(-2). The emitted light from the OLED device is green, and has the color coordinates of (x, y) (0.33, 0.54) according to CIE. Electrochemical and optical properties were also studied by using cyclic voltammetry, UV-Vis absorption and fluorescence spectroscopy, respectively.
Fluorene-Carbazole Dendrimers: Synthesis, Thermal, Photophysical and Electroluminescent Device Properties
(Wiley-V C H Verlag Gmbh, 2010) Usluer, Ozlem; Demic, Serafettin; Egbe, Daniel A. M.; Birckner, Eckhard; Tozlu, Cem; Pivrikas, Almantas; Ramil, Alberto Montaigne; Sariciftci, Niyazi Serdar
Novel hole-transporting dendrimeric molecules containing dioctylfluorene, spirobi(fluorene) and spiro(cylododecane-fluorene) as the core unit and different numbers of carbazole and thiophene moieties as the peripheral groups are synthesized. All the dendrimers are characterized by H-1 NMR, C-13 NMR, FTIR, UV-vis, PL spectroscopy, and MALDI-TOF. They are thermally stable with high glass transition and decomposition temperatures and exhibit chemically reversible redox processes. They are used as the hole-transporting layer (HTL) material for multilayer organic light emitting diodes (OLEDs) with a low turn-on voltage of around 2.5 V and a bright green emission with a maximum luminance of around 25400 cd m(-2).
Modification of ITO surface using aromatic small molecules with carboxylic acid groups for OLED applications
(Elsevier Science Sa, 2011) Havare, Ali Kemal; Can, Mustafa; Demic, Serafettin; Okur, Salih; Kus, Mahmut; Aydin, Hasan; Yagmurcukardes, Nesli; Tari, Suleyman
4-[(3-Methylphenyl)(phenyl)amino]benzoic acid (MPPBA) was synthesized in order to facilitate the hole-injection in Organic Light Emitting Diodes (OLED). MPPBA was applied to form self-assembled monolayer (SAM) on indium tin oxide (ITO) anode to align energy-level at the interface between organic semiconductor material (TPD) and inorganic anode (ITO) in OLED devices. The modified surface was characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). KPFM was used to measure the surface potential and work function between the tip and the ITO surface modified by SAM technique using MPPBA. The OLED devices (ITO/MPPBA/TPD/Alq(3)/Al) fabricated with SAM-modified ITO substrates showed lower turn-on voltages and enhanced diode current compare to the OLED devices fabricated with bare ITO substrates. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.
A new conducting polymer of 2,5-bis(2-thienyl)-1H-(pyrrole) (SNS) containing carbazole subunit: Electrochemical, optical and electrochromic properties
(Elsevier Science Sa, 2009) Koyuncu, Sermet; Zafer, Ceylan; Sefer, Emre; Koyuncu, Fatma Baycan; Demic, Serafettin; Kaya, Ismet; Ozdemir, Eyup; Icli, Siddik
We report here the synthesis of a new electroactive monomer 3,6-di-tert-butyl-[4-(2,5-di-2-thienyl-1H-pyrrol-1-yl)phenyl]-9H-carbazole in five steps and polymerization of this monomer by two different procceses: Kumada Coupling and electro-oxidative. The product obtained by chemical polymerization exhibits a high thermal stability and narrow molecular weight distribution. While, in the UV-vis absorption spectrum of monomer the absorption peaks appear at 338 nm, the chemically synthesized polymer absorbs at 428 nm with 90 nm red shift. Cyclic voltammogram of monomer shows two separate oxidation processes which reflect the first oxidation at +0.84 V and a second one at +1.43 V. When the polymeric film prepared by electrochemical process was subjected to a repeated cyclic scan between -0.2V and +1.0V, it switches among three different colors (orange, green and blue). The oxidation and reduction response times were calculated as 2.0 s for this polymer film and exhibits high redox stability. The results anticipate that this kind of polymers can be used for designing electrochromics based on the use of one molecule for the generation of three basic colors (RGB). (C) 2009 Elsevier B.V. All rights reserved.
A new conducting polymer of 2,5-bis(2-thienyl)-1H-(pyrrole) (SNS) containing carbazole subunit: Electrochemical, optical and electrochromic properties
(Elsevier Science Sa, 2009) Koyuncu, Sermet; Zafer, Ceylan; Sefer, Emre; Koyuncu, Fatma Baycan; Demic, Serafettin; Kaya, Ismet; Ozdemir, Eyup; Icli, Siddik
We report here the synthesis of a new electroactive monomer 3,6-di-tert-butyl-[4-(2,5-di-2-thienyl-1H-pyrrol-1-yl)phenyl]-9H-carbazole in five steps and polymerization of this monomer by two different procceses: Kumada Coupling and electro-oxidative. The product obtained by chemical polymerization exhibits a high thermal stability and narrow molecular weight distribution. While, in the UV-vis absorption spectrum of monomer the absorption peaks appear at 338 nm, the chemically synthesized polymer absorbs at 428 nm with 90 nm red shift. Cyclic voltammogram of monomer shows two separate oxidation processes which reflect the first oxidation at +0.84 V and a second one at +1.43 V. When the polymeric film prepared by electrochemical process was subjected to a repeated cyclic scan between -0.2V and +1.0V, it switches among three different colors (orange, green and blue). The oxidation and reduction response times were calculated as 2.0 s for this polymer film and exhibits high redox stability. The results anticipate that this kind of polymers can be used for designing electrochromics based on the use of one molecule for the generation of three basic colors (RGB). (C) 2009 Elsevier B.V. All rights reserved.
New perylene derivative dyes for dye-sensitized solar cells
(Elsevier Science Bv, 2007) Zafer, Ceylan; Kus, Mahmut; Turkmen, Gulsah; Dincalp, Haluk; Demic, Serafettin; Kuban, Baha; Teoman, Yildirim; Icli, Siddik
We have studied the influence of the spacer alkyl chain length of perylenemonoimide (PMI) dyes on the device performance in dye-sensitized solar cells (DSSCs). We observed that the dyes with longer and brunched alkyl chains exhibit higher efficiencies in DSSCs. In line with these statements we now report the highest efficiency obtained under standard conditions for a perylene imide derivative with PMI-DA1 that performs 300 mV open circuit voltage, 9.79 mA/cm(2) short-circuit current and 1.61% overall conversion efficiency. (c) 2006 Published by Elsevier B.V.
A Novel High-Contrast Ratio Electrochromic Material from Spiro[cyclododecane-1,9 '-fluorene]bicarbazole
(Wiley-Blackwell, 2011) Usluer, Ozlem; Koyuncu, Sermet; Demic, Serafettin; Janssen, Rene A. J.
A novel electroactive spirocyclododecylfluorene monomer named 2,7-bis(carbazol-9-yl)-9,9'-spiro[cyclododecane- 1,9'-fluorene] (SFC) was synthesized and electrochemically polymerized to give a very stable multi-electrochromic polymer (poly-SFC). Two separate oxidation processes were observed for both SFC monomer and poly-SFC that carries two carbazole units. The polymeric film of poly-SFC was coated onto ITO/glass surface, and it shows different colors (transparent, yellowish green, green, and dark green) upon stepwise oxidations. An electrochromic device based on poly-SFC was assembled in the sandwich cell configuration of ITO/poly-SFC// gel electrolyte//PEDOT/ITO. Poly-SFC exhibits 90% of transparency at neutral state and a high contrast ratio (Delta T = 58% at 800 nm). This device constructed from it represents a response time of about 1 s, high coloration efficiency (1377 cm(2) C-1) and retained its performance by 96.4% even after 1000 cycles. Exhibiting high transparency at neutral state, reversible redox behavior, resistance to overoxidation, and especially high contrast ratio at near IR region can make poly-SFC be useful and promising candidate for electrochromic applications despite having a relatively slow response time. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 333-341, 2011
One-step preparation of binder-free nickel-containing graphene foam electrode for supercapacitors
(Wiley, 2024) Gultekin, Sirin Siyahjani; Karimi, Aziz Ahmad; Can, Mustafa; Demic, Serafettin
In this study, a nickel hydroxide (Ni(OH)2)-modified reduced graphene oxide (rGO) foam electrode for supercapacitor application is presented. The electrode was prepared without using a binder through a one-step process with three different ratios (NirGO1, NirGO2, and NirGo3). To compare the supercapacitor performance of the obtained graphene foam electrodes, rGO and rGO:carbon black (CB) standard electrodes with PVDF-HFP binder were also prepared. All electrodes were then characterized structurally (XPS, EDS, RAMAN, XRD, and FT-IR) and morphologically (SEM). Structural characterizations demonstrated that the Ni-containing electrodes were in alpha-Ni(OH)2:rGO structure. In addition, NirGO3 exhibited a specific capacitance of 800 F g-1 which is relatively the highest performance between the foam electrodes, while rGO:CB presented a specific capacitance of 900 F g-1. The results demonstrated that with the method proposed for electrode development, it was possible to obtain comparable results with the standard electrode rGO:CB. image
The performance of OLEDs based on sorbitol doped PEDOT:PSS
(Elsevier Science Sa, 2012) Havare, Ali Kemal; Can, Mustafa; Demic, Serafettin; Kus, Mahmut; Icli, Siddik
We report the performance of OLED devices with a configuration of FTO/sorbitol-PEDOT:PSS (60 nm)/TPD (50 nm)/Alq(3) (40 nm)/Al (120 nm) and FrO/plain-PEDOT:PSS (60 nm)/TPD (50 nm)/Alq(3) (40 nm)/Al (120 nm) prepared from poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) undoped (plain-PEDOT:PSS) and doped by a constant concentration 5% of sorbitol, respectively. The OLED devices were tested in terms of electrical and optical characteristics in order to investigate the effect of sorbitol doping and thermal annealing on PEDOT:PSS thin film on FTO. The device fabricated from sorbitol-PEDOT:PSS with thermal annealing showed the maximum luminance of 130 (cd m(-2)). The devices with sorbitol doping showed a lowering of the operating voltage from 6.5 down to 3 V. A constant luminous efficiency higher than 1.8 cd A(-1) was obtained in the range of current of 4-7 (mA/cm(2)) with doped sorbitol. Published by Elsevier B.V.
Push-pull type material having spirobifluorene as pi-spacer for dye sensitized solar cells
(Pergamon-Elsevier Science Ltd, 2016) Can, Mustafa; Bilgili, Hakan; Demirak, Kadir; Gultekin, Burak; Koyuncu, Sermet; Kus, Mahmut; Zafer, Ceylan; Demic, Serafettin; Icli, Siddik
Two organic dyes for dye-sensitized solar cells (DSSC) based on spirobifluorene were synthesized and characterized. Electrochemical, spectroscopic and photovoltaic properties of the dyes have been investigated. Hexyloxy substituted triarylamine was used as electron donating moiety in the molecule while spirobifluorene and cyanoacrylic acid were used as pi-bridge and acceptor groups, respectively. MK162-sensitized solar cells exhibited a short-circuit current (I-SC) of 4,92 mA cm(-2), an open-circuit voltage (V-OC) of 520 mV and a fill factor (FF) of 0.59, resulting an overall power conversion efficiency of 1,52 where the reference cell, Z907 was yielded an overall conversion efficiency of 4.08% efficiency with 620 mV of V-OC and 14.51 mA cm(-2) of Isc under standard AM 1.5 illumination. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Structure-Property Relationship in Amber Color Light-Emitting Electrochemical Cell with TFSI Counteranion: Enhancing Device Performance by Different Substituents on N boolean AND N Ligand
(Amer Chemical Soc, 2021) Demir, Nuriye; Karaman, Merve; Yakali, Gul; Tugsuz, Tugba; Denizalti, Serpil; Demic, Serafettin; Dindar, Bircan
Amber color emitting novel Ir(III) complexes were synthesized: [Ir-(Meppy)(2)( Fpbpy)][ PF6] ( 1bPF6), [Ir(Meppy) 2( Fpbpy)][TFSI] ( 1bTFSI), [Ir(Meppy)(2)(MeObpy)][PF6] (2bPF6) and [Ir(Meppy)2(MeObpy)][TFSI] (2bTFSI), where Meppy = 2-(p-methylphenyl)-pyridine (b), Fpbpy = 4,4'-bis(4-fluorophenyl)-2,2'-bipyridine (1), and MeObpy = 4,4'-bis(4-methoxy)-2,2'-bipyridine (2). The photophysical and X-ray results showed that the complexes have aggregation-induced phosphorescent emission (AIPE) and a salt-induced polymorphism effect. The highest photoluminescence intensity was observed in complex 2bTFSI compared to other complexes in the solid state. Their theoretical absorption and phosphorescence emission transitions in acetonitrile were also investigated by using double- and triple-. basis sets with B3LYP and PBE0 hybrid functional. The best lightemitting electrochemical cell (LEC) performance was exhibited by complex 2bTFSI, and the data obtained were as follows: Luminance, current density, luminous efficiency, turn-on time, power efficiency, and external quantum efficiency were measured as 16 156 cd/m2, 554 mA/cm(2), 8.49 cd/A, 17 s, 3.95 lm/W and 6.37%, respectively. The investigation of crystallographic characteristics have shown that the LEC performance of these complexes depends on cationic-anionic interaction which has a significant influence on molecular stacking of the molecules. Because, complex 2bTFSI, with weak cationic-anionic interactions, shows strong p center dot center dot center dot p stacking interactions between the adjacent molecules, it is the best lighting application candidate among the complexes.
Synthesis and photovoltaic characterization of triarylamine-substituted quinoxaline push pull dyes to improve the performance of dye-sensitized solar cells
(Scientific Technical Research Council Turkey-Tubitak, 2017) Demirak, Kadir; Can, Mustafa; Ozsoy, Cihan; Yigit, Mesude Zeliha; Gultekin, Burak; Demic, Serafettin; Zafer, Ceylan
Novel unsymmetrical organic sensitizers having donor, pi-spacer, and anchoring groups were designed and synthesized for dye-sensitized solar cell (DSSC) application. The dyes 3-{4-[7-(4-{bis[4-(hexyl)phenyl]amino} phenyl)-11,12-dibutoxy-1,4,5,8-tetrahydrodibenzo [a, c] phenazine-2-yl]phenyl} -2-cyano acrylic acid (KD-148) and 3-{5-[7-(4{bis[4-(hexyloxy)phenyl]amino} phenyl)-11,12-dibutoxy-1,4,5,8-tetrahydrodibenzo [a, c] phenazine-2-yl]-2-thienyl} -2-cyano acrylic acid (KD-150) were anchored onto TiO2 and tested with ionic liquid electrolyte. The monochromatic incident photon-to-current conversion efficiencies (IPCE) of the dyes were 50% and 60% at 420 nm, respectively. The KD-150 sensitized solar cell gave a short-circuit current (I-SC) of 7.37 mA/cm(2) an open-circuit voltage (V-oc) of 560 mV, a fill factor (FF) of 0.56, and overall conversion efficiency (eta) of 2.32% whereas the standard dye Z-907 dye exhibited 14.51 mA/cm2 of I-SC, 630 mV of V-oc, 0.45 of FF, and 4.08% of eta under AM 1.5 illumination with power of 100 mW/cm(2).

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