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• MakaleAçık Erişim2026Scopus SJRQ2/r/bayburt/12820
  Exploring the role of rare earth elements doped TiO₂ based photoanodes on the performance of dye-sensitized solar cells

  Caliskan, Berrak; Sayan, Enes; Igman, Erdal

  This study investigates the synthesis and characterization of rare earth elements (REEs) doped TiO₂ thin films based photoanodes for use in dye-sensitized solar cells (DSSCs). For this purpose, TiO₂ films were doped with Ho³⁺, La³⁺, Er³⁺, and Yb³⁺ ions to enhance photoelectrochemical properties. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, BET surface area analysis, and X-ray photoelectron spectroscopy (XPS) were employed for the structural, morphological, and optical characterization of the synthesized photoanodes and CEs. REEs doping improved the surface morphology and optical properties of TiO₂, in particular, it increased photon absorption in the visible light range. La³⁺ and Ho³⁺ significantly improved photovoltaic performance, achieving power conversion efficiencies of 3.78% and 2.87%, respectively, compared to that of pure TiO₂. These enhancements indicate improved charge transport and light harvesting due to incorporation of REEs. Additionally, replacing the conventional platinum counter electrode (CE) with reduced graphene oxide (rGO) further enhanced performance, offering a low-cost and efficient alternative. The study highlights the combined benefits of REEs doping and rGO integration in improving DSSCs efficiency. These findings contribute to the development of more sustainable, cost-effective solar energy technologies and underline the potential of REEs-doped TiO₂ films and rGO electrodes in advancing next-generation photovoltaic devices.

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  AtıfScopus3·WoS3·OpenAlex2

  İncele
• MakaleAçık Erişim2026Scopus SJRQ2/r/bayburt/11359
  Exploring the ımpact of metal doping and alternative electrodes on the performance of dye-sensitized solar cells

  Calıskan, Berrak; Sayan, Enes; Igman, Erdal

  This study explores the synthesis and characterization of metal-doped TiO2 thin films for applications in dye-sensitized solar cells (DSSCs). Titanium dioxide (TiO2) films were doped with various metal ions such as Ag+, Zn2+, Fe3+, and Co2+, to enhance the photoelectrochemical properties of the photoanode. The films were characterized using various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). The doping process was found to influence the morphology, surface area, and optical properties of the TiO2 films, resulting in enhanced light absorption, particularly in the visible range. The effects of metal doping on the performance of the DSSCs were evaluated, showing that Co2+ and Ag+ doping resulted in improved efficiency compared to undoped TiO2, with the Co2+-doped TiO2 achieving the highest power conversion efficiency of 2.85%. Additionally, the incorporation of reduced graphene oxide (rGO) as a counter electrode demonstrated a significant enhancement in DSSC performance, even surpassing traditional platinum-based counter electrodes. The results suggest that metal doping and rGO incorporation offer promising strategies for improving DSSC efficiency. This study highlights the potential of metal-doped TiO2 photoanodes and rGO counter electrodes in advancing the development of cost-effective, high-performance DSSCs for sustainable solar energy applications.

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  AtıfScopus1·WoS1

  İncele
• MakaleAçık Erişim2021Scopus SJRQ1/r/bayburt/12163
  Photovoltaic performance of non-covalent functionalized single-layer graphene in dye-sensitized solar cells (DSSCs)

  Igman, Erdal; Bayram, Ozkan; Mavi, Ahmet; Hasar, Ugur Cem; Simsek, Onder

  In this study, it was aimed to fabricate new effective alternative counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). For this purpose, firstly, single-layer graphene (SLG) thin films were grown by chemical vapor deposition (CVD) method. Then, these films were separately functionalized with 1,8-cineole (ppCin/SLG), D-Limonene (ppLim/SLG) and Thiophene (ppTh/SLG) by plasma polymerization. Number of layers in CVD-grown graphene determined by Raman, transmission electron microscope (TEM) and ultraviolet–visible (UV–Vis) spectroscopy. Chemical structures of plasma polymerised (pp) thin films were investigated by Fourier transform infrared (FTIR) spectroscopy. Photovoltaic parameters of DSSCs were calculated, and electrocatalytic properties of CEs were investigated by electrochemical impedance spectroscopy (EIS). Polymer functionalization greatly enhanced the electrical conductivity and electrocatalytic activity properties of graphene compared to that of SLG. The efficiencies of DSSCs with ppCin/SLG and ppLim/SLG CEs were 1.10% and 1.02%, respectively. As a result, the cell efficiencies of ppCin/SLG and ppLim/SLG could be as alternative materials to platinum (Pt) counter electrode.

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  AtıfScopus14·WoS13·OpenAlex14

  İncele
• MakaleAçık Erişim2020Scopus SJRQ2/r/bayburt/12153
  Graphene/polyaniline nanocomposite as platinum-free counter electrode material for dye-sensitized solar cell: its fabrication and photovoltaic performance

  Bayram, Ozkan; Igman, Erdal; Guney, Harun; Demir, Zeynep; Yurtcan, Mustafa Tolga; Cirak, Cagri; Hasar, Ugur Cem; Simsek, Onder

  In this study, it was aimed to produce graphene/polyaniline nanocomposite thin films as counter electrode materials by PECVD system and to determine the photovoltaic performances of these counter electrodes in dye-sensitized solar cells (DSSCs). Graphene/polyaniline counter electrode (GPCE) material was produced in two different steps. Firstly, a single-layer and multilayer graphene thin films were produced on the fluorine-doped tinoxide (FTO) substrates. Then, polyaniline (PANI) thin films were grown on each graphene thin films using plasma polymerization technique, and eventually the production of the graphene/PANI nanocomposite was completed. The fabricated graphene/PANI nanocomposites were used in place of platinum (Pt)-counter electrode which is widely used in DSSCs and the photovoltaic performance of these counter electrodes was investigated. The DSSCs consisted of titanium dioxide (TiO2) nanotube photoanode, N719 dye, iodolyte liquid electrolyte, and graphene/PANI nanocomposite counter electrode. I–V measurements were carried out in order to calculated photoconversion efficiency (PCE) and it was found that the these efficiency of GPCEs changed between 0.56 and 1.36% according to the number of graphene layers. The photovoltaic performance of DSSC, consisting of TiO2 nanotube photoanode and Pt-counter electrode was 1.1%.

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  AtıfScopus33·WoS25·OpenAlex29

  İncele
• MakaleAçık Erişim2019/r/bayburt/15100
  Cvd ve pecvd tekniği kullanılarak bakır folyolar üzerinde grafen nanoyapıların elde edilmesi ve karakterizasyonu

  Bayram, Ozkan; İğman, Erdal; Simsek, Onder

  Bu çalışmada, CH4 gazı kullanılarak bakır folyolar üzerinde grafen ince filmlerin sentezlenmesi amaçlanmıştır.İnce filmlerin elde edilebilmesi için plazma destekli kimyasal buhar biriktirme (PECVD) ve kimyasal buharbiriktirme (CVD) yöntemi kullanılmıştır. Bakır alt-taşlar, standart ön temizlik yapıldıktan sonra kuvars camdanyapılmış reaktöre yerleştirilmiştir. Vakum odasının taban basıncı 5-10 mTorr’a düşürüldükten ve hidrojen gazıile tavlama işlemi yapıldıktan sonra, CH4 gazı ortama gaz akış kontrol ünitesi yardımıyla gönderilmiştir. PECVDsisteminde; RF güç kaynağı (13,56 MHz), kontrol ünitesi vasıtasıyla aktif hale getirilerek, üretilen enerji ortamagönderilmiştir. İşlem basıncı 100 mTorr, sıcaklık 600 ˚C, RF gücü 50 W ve kaplama süresi ise 20 dakika olarakayarlanmıştır. CVD tekniğinde ise, RF gücü ortadan kaldırılmış ve büyütme sıcaklığı 1000 ˚C olarakbelirlenmiştir. Elde edilen Grafen nanoyapıların karakterizasyonu için Raman, SEM ve TEM analizlerigerçekleştirilmiştir. Raman sonuçlarına göre, CVD yöntemiyle elde edilen yapılar, tek tabaka grafen yapısınıdoğrulamıştır. Bununla beraber PECVD tekniği ile tek tabaka grafen nanoyapılardan ziyade çok tabakalı yapıelde edildi.

  AtıfOpenAlex1

  İncele
• MakaleAçık Erişim2019Scopus SJRQ2/r/bayburt/13630
  The role of cobalt doping on the optical and structural properties of Mn 3 O 4 nanostructured thin films obtained by SILAR technique

  Bayram, Ozkan; İgman, Erdal; Guney, Harun; Simsek, Onder

  Cobalt doped manganese oxide thin films (Mn 3 O 4 :Co) were successfully deposited on soda lime glass substrates using SILAR technique. Mn 3 O 4 :Co thin films were characterized using XRD, SEM, Uv–VIS and Raman spectroscopy. The XRD spectra showed that thin films had substantially Hausmannite crystal structure. The preferential orientation of the pure and 0.5 at.% Co doped manganese oxide thin films (Mn 3 O 4 ) was (002), but with increasing Co doping, it was detected that this preferential orientation shift towards the (211) plane. The absorbance, transmittance and optical band gap of the Mn 3 O 4 :Co thin films were determined using Uv–Vis spectroscopy and these properties of the thin films differed considerably due to cobalt doping. The optical band gap of pure Mn 3 O 4 thin films was 2.00 eV, but on the other hand, due to the Co doping this value increased before and then decreased slightly. Optical transmittance of Mn 3 O 4 :Co films increased from 60% to 72% with the effect of Co doping. A1g mode, which is the characteristic vibration peak of Mn 3 O 4 films, was confirmed for pure and doped Mn 3 O 4 thin films at a wavelength of 658 nm.

  AtıfScopus26·WoS24·OpenAlex25

  İncele
• MakaleAçık Erişim2019Scopus SJRQ2/r/bayburt/12318
  Investigation of structural, morphological and optical properties of Nickel-doped Zinc oxide thin films fabricated by co-sputtering

  Bayram, Ozkan; Sener, Emre; İgman, Erdal; Simsek, Onder

  In this study, it was aimed to grow Nickel doped (0.0 at.%, 0.16 at.%, 0.20 at. % and 0.24 at. %) Zinc Oxide (NZO) thin films on quartz substrates using Magnetron Sputtering technique. NZO thin films were obtained at a temperature of 450 °C, a pressure of 480 m Torr and a deposition time of 30 min. Co-sputtering process for both Ni and ZnO target was performed using two separate power sources. The DC power of the Ni target material was 20, 30 and 40 W, respectively while the radio frequency (RF) power of the Zinc oxide (ZnO) target material was set to 150 W. Using XRD analysis, thin films were found to have polycrystalline morphology, and the average crystallite size changed significantly depending on the increased Ni doping level. The optical Transmittance of the thin films was greater than 90% in the visible region (550 nm), and this value tends to decrease slightly by Ni doping. The optical band gap (E g ) firstly decreased and then slightly increased with the Nickel doping ratio and these values were found to be 3.23 eV, 3.11 eV and 3.15 eV, respectively, with increase of Ni doping.

  AtıfScopus34·WoS30·OpenAlex37

  İncele
• MakaleAçık Erişim2018Scopus SJRQ2/r/bayburt/12524
  Synthesis and characterization of Zn-doped Mn3O4 thin films using successive ionic layer adsorption and reaction technique: Its structural, optical and wettability properties

  Bayram, Ozkan; Ertargin, Mehmet Emrah; Igman, Erdal; Guney, Harun; Simsek, Onder

  In this study, it is aimed to obtain Zn doped Mn3O4 (manganese oxide) nanostructured thin films on the soda lime glass substrates by successive ionic layer adsorption and reaction technique. The tetragonal crystal structure of the all thin films was detected using XRD spectroscopy. The average crystallite size of undoped Mn3O4 thin films was calculated to be 29 nm and for Zn-doped thin films, this value decreased to 23 nm with increasing Zn concentration. Characteristic peaks for thin films were also confirmed by RAMAN spectroscopy. The morphological structures of zinc-doped manganese oxide nano-sheets thin films were revealed by SEM. Using UV–Vis spectroscopy, it was found that the optical band gap of Mn3O4 thin films decreased from 2.05 to 1.73 eV with Zn doping. It has also been understood from the wettability analyzes of thin films that all thin films have a hydrophilic character. From all these analyzes, it is thought that the Zn doped Mn3O4 thin films have the potential to be used in supercapacitor applications.

  AtıfScopus25·WoS22·OpenAlex25

  İncele
• MakaleAçık Erişim2018Scopus SJRQ2/r/bayburt/12377
  Effect of doping concentration on the structural and optical properties of nanostructured Cu-doped Mn3O4 films obtained by SILAR technique

  Bayram, Ozkan; Guney, Harun; Ertargin, Mehmet Emrah; Igman, Erdal; Simsek, Onder

  In this study, the effect of Cu doping on the optical, structural and wettability properties of the nanostructured Cu-doped Mn3O4 (CMO) thin films obtained by using successive ionic layer adsorption and reaction technique was systematically investigated. The optical, morphological, structural and wettability properties of the nanostructured CMO films were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis spectroscopy, and water contact angle (WCA) measurements. There were significant differences in the crystal structure of the nanostructured CMO thin films. The Cu doping disrupted this structure of pure (undoped) Mn3O4 films and caused the formation of the porous structure. Optical properties such as extinction coefficient, refractive index, and dielectric constants and optical band gap, were determined for nanostructured CMO films. Compared with pure films, the band gap of Cu-doped films decreased from 2.06 to 1.71 eV with increasing Cu concentration. The dielectric constants of the films showed that the nanostructured CMO films have a transparent structure. At 300 nm wavelength, the dielectric constants of pure Mn3O4 films were 2.22 while the calculated dielectric constants at increasing doping concentrations were 3.55, 2.41 and 2.25. It was also found from the WCA measurements that the thin films were hydrophilic in character and the WCA values for the nanostructured CMO thin films were measured as 24, 29 and 40 of degree.

  AtıfScopus23·WoS22·OpenAlex26

  İncele
• MakaleAçık Erişim2018Scopus SJRQ2/r/bayburt/12305
  Effect of the number of cycles on the optical and structural properties of Mn3O4 nanostructures obtained by SILAR technique

  Bayram, Ozkan; Simsek, Onder; Guney, Harun; Igman, Erdal; Murat Ozer, Mustafa

  In this study, nanostructured Mn3O4 (manganese oxide) thin films were successfully obtained by successive ionic layer adsorption and reaction (SILAR) method on the soda lime glass substrates using Manganese Nitrate (Mn(NO3)2) and Ammonium hydroxide (NH4(OH)) as cationic and anionic precursors respectively. Structural and morphological characterizations of the Mn3O4 films obtained at different cycles were determined using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The crystal structure of the thin films were also confirmed by RAMAN spectroscopy. Optical properties such as absorption, transmission, reflection, extinction coefficient and optical band gap of nanostructured Mn3O4 thin films were determined by UV–Vis spectroscopy. SEM images showed that the manganese oxide nanosheets formed uniformly on substrate surface. As the deposition cycles increased, nano-sheets structure deteriorated. The optical band gap of Mn3O4 thin films varied from 2.12 to 2.59 eV, depending on the increase in number of cycles. From contact angle measurements of thin films, it was determined that thin films had hydrophilic character.

  AtıfScopus14·WoS14·OpenAlex16

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