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Öğe A research on growth and characterization of CdS:Eu thin films(Springer Heidelberg, 2019) Yilmaz, S.; Polat, I.; Tomakin, M.; Bacaksiz, E.Chemical spray pyrolysis-grown CdS thin films including various quantities of Eu atoms (from 0 to 10at.%) were synthesized on glass slides. The detailed physical properties of the produced CdS and CdS:Eu thin films were explored. Structural analysis showed that Eu-doping enhanced the crystal quality of CdS thin films until 10at.% Eu-doping and further Eu-doping treatment led to a distortion in the CdS structure. In addition, the crystallite sizes of CdS thin films dropped from 36.2 to 32.4nm as Eu-doping level increased to 10at.%. Morphological data showed that increasing Eu-doping remarkably varied the surface morphology of CdS thin films forming smaller grains. Chemical content examinations approved the presence of Eu atoms in CdS structure. From the optical measurements, it was obtained that more transparent CdS thin films with a maximum transmittance of 68% at 820nm were created after 10at.% Eu-doping and bandgap values of samples reduced from 2.58 to 2.47eV with rising of Eu-doping from 0 to 10at.%. Room temperature photoluminescence data demonstrated the formation of two essential peaks for all the samples, which are in turn related to green and yellow bands. Electrical investigation pointed out that Eu-doping enhanced the carrier density of CdS thin films from 4.38 x 10(13) cm(-3) to 2.46 x 10(14) cm(-3) and dropped the resistivity of CdS samples from 2.59 x 10(4) cm to 5.85 x 10(3) cm until 6at.% and further increment of Eu-doping paved the way to get worse electrical data. Thus, it can be brought a conclusion that Eu-doping not only improved the optical properties of CdS thin films, but also restored the electrical properties, which are able to use in the opto-electronic devices.Öğe Alloying and phase transformation in CdS/CdSe bilayers annealed with or without CdCl2(Elsevier Sci Ltd, 2019) Ciris, A.; Basol, B. M.; Yilmaz, S.; Atasoy, Y.; Tomakin, M.; Kucukomeroglu, T.; Bacaksiz, E.The present paper studies the structural, compositional, morphological and optical properties of thin CdS/CdSe stacks annealed in an inert atmosphere or subjected to a CdCl2 treatment. The bilayer stacks were fabricated by chemical bath deposition (CBD) of a 50 nm thick CdS layer followed by evaporation of a CdSe film with equal thickness. It was found that when this stack was annealed at 400 degrees C for up to 10 min, no appreciable intermixing/alloying between the two layers was detected. Upon heating for 5-10 min in presence of a CdCl2 layer disposed over the CdSe film, however, led to appreciable alloying and formation of CdSSe, which was confirmed through XRD, optical transmission and room temperature photoluminescence measurements. XRD data further showed that the CdS layer in the CdS/CdSe stack had nano-amorphous structure that did not change upon annealing in inert atmosphere. The CdSe layer of the stack, which had a cubic structure, also preserved its phase upon annealing in inert atmosphere. When the CdS/CdSe stack was CdCl2 treated, the phase of the CdSSe alloy formed was transformed to hexagonal. These observations may have consequences in applications where CdS/CdSe bilayers are formed within device structures and subjected to various types of heat treatments.Öğe Alloying and phase transformation in CdS/CdSe bilayers annealed with or without CdCl2(Elsevier Sci Ltd, 2019) Ciris, A.; Basol, B. M.; Yilmaz, S.; Atasoy, Y.; Tomakin, M.; Kucukomeroglu, T.; Bacaksiz, E.The present paper studies the structural, compositional, morphological and optical properties of thin CdS/CdSe stacks annealed in an inert atmosphere or subjected to a CdCl2 treatment. The bilayer stacks were fabricated by chemical bath deposition (CBD) of a 50 nm thick CdS layer followed by evaporation of a CdSe film with equal thickness. It was found that when this stack was annealed at 400 degrees C for up to 10 min, no appreciable intermixing/alloying between the two layers was detected. Upon heating for 5-10 min in presence of a CdCl2 layer disposed over the CdSe film, however, led to appreciable alloying and formation of CdSSe, which was confirmed through XRD, optical transmission and room temperature photoluminescence measurements. XRD data further showed that the CdS layer in the CdS/CdSe stack had nano-amorphous structure that did not change upon annealing in inert atmosphere. The CdSe layer of the stack, which had a cubic structure, also preserved its phase upon annealing in inert atmosphere. When the CdS/CdSe stack was CdCl2 treated, the phase of the CdSSe alloy formed was transformed to hexagonal. These observations may have consequences in applications where CdS/CdSe bilayers are formed within device structures and subjected to various types of heat treatments.Öğe An evaluation of structural, optical and electrical characteristics of Ag/ZnO rods/SnO2/In-Ga Schottky diode(Springer, 2018) Kucukomeroglu, T.; Yilmaz, S.; Polat, I.; Bacaksiz, E.ZnO rods were successfully deposited on ZnO seeded SnO2 coated glass substrates by a spray pyrolysis route. It was seen that the grown ZnO sample had a wurtzite structure with a well-defined hexagons of similar to 1-3 A mu m in diameter. Photoluminescence results measured at 300 K indicated that ZnO rods had a ultra-violet peak located at 383 nm without a deep level band emission. ZnO rods were subsequently used to realize a Ag/ZnO rods/SnO2/In-Ga Schottky diode which displayed rectifying current-voltage (I-V) characteristic with a turn on voltage of 1.2 V at 300 K. Electrical parameters of the Ag/ZnO rods/SnO2/In-Ga Schottky diode were further examined by (I-V) characteristics at the temperature range of 125-300 K with a step of 25 K. Using thermionic emission theory (TET), it was found that the ideality factor reduced with the increase of temperature whereas the zero bias barrier height increased with the increment of the temperature. Using ln(I (0) )/T (2) versus q/nkT plot, Richardson constant (A*) and zero bias barrier height (I broken vertical bar (B0)) was obtained as 3.27 x 10(-5) A m(-2) K-2 and 0.32 eV, respectively. After applying TET with the assumption of Gaussian distribution, a mean barrier height and the modified Richardson constant (A**) were determined to be 0.88 eV and 2.75 x 10(5) A m(-2) K-2.Öğe CBD-synthesized Mg-doped CdS thin films for hybrid solar cells and self-powered photodetectors(Elsevier, 2025) Yilmaz, S.; Toreli, S. B.; Tomakin, M.; Polat, I. .; Bacaksiz, E.Mg-doped CdS samples were deposited via chemical bath deposition onto fluorine-doped tin oxide slides with varying levels of Mg-doping. Structural analysis revealed improved crystal quality in CdS films upon Mg incorporation. Morphological examinations indicated a reduction in grain size alongside appearance of smooth, void-free surfaces particularly evident at 3 % Mg-doping. Mg-doping also resulted in enhanced transparency of CdS films, notably at 3 % and 5 % within the visible spectrum. Efficient exciton dissociation was observed in hybrid solar cells based on 1 % and 3 % Mg-doped CdS, as evidenced by photoluminescence. Top-performing solar cell achieved an efficiency of 0.220 %, nearly seven times that of control device. 5 % Mg-doped CdSbased photodetectors exhibited favorable photosensing characteristics: a responsivity of 0.011 A/W, detectivity of 4.4 x 108 Jones, external quantum efficiency of 3.1 %, and rise/decay times of 26/25 ms at zero bias. These findings underscore beneficial effects of Mg-doping on both hybrid solar cell and self-driven photodetector performance.Öğe CdCl2 treatment and its role in enhancing photodetection properties of CdTe and Cd1-xZnxTe films(Elsevier, 2025) Yilmaz, S.; Basol, B. M.; Polat, I.; Daday, M. Taykurt; Tomakin, M.; Kucukomeroglu, T.; Bacaksiz, E.Close space sublimated CdTe and Cd1-xZnxTe (CZT) films were grown on glass substrates and CdCl2 activation was applied on these films to improve their physical, optical and electrical characteristics for photodetector applications. X-ray diffraction data showed that CdCl2 treatment of CdTe caused a reduction in the dislocation density and microstrain, whereas Zn incorporation/CdCl2 treatment slightly increased these values compared to the as-deposited CdTe films. Morphological examination indicated that CdCl2 activation transformed grains from faceted to rounded shape for both CdTe and CZT films. A band gap enlargement was observed from 1.45 eV to 1.47 eV for both CdTe and CZT films upon CdCl2 treatment. CdCl2-treated CZT films were used to fabricate photodetectors that exhibited the highest performance with a rise/fall time of 27/28 ms, sensitivity of 1301 %, responsivity of 0.0143 A/W, detectivity of 5.7x107 Jones and external quantum efficiency of 4.0 % under blue light illumination at 2 V.Öğe CdSe thin films-based photodetector doped with Cu, In and Ga atoms: a comparative work(Springer Heidelberg, 2023) Yilmaz, S.; Polat, I.; Tomakin, M.; Kucukomeroglu, T.; Bacaksiz, E.The present work demonstrates a comparison of performance of Cu, In and Ga-doped CdSe thin films-based photodetectors. Structural, morphological, optical and electrical investigation of Cu, In and Ga-doped CdSe thin films prepared by close space sublimation on glass slides is also achieved. It is obtained that Cu, In and Ga-doped CdSe thin films have a good crystal quality with a hexagonal structure in the preferred orientation along (002) plane. Morphological examination shows that Cu-doped CdSe thin films grow in the porous microstructure while In and Ga-doped CdSe films possess compact and uniform morphology without any voids. Transparency of In and Ga-doped CdSe films are higher than that of Cu-doped CdSe throughout the entire spectrum. Band gap values of all the samples are determined to be almost 1.72 eV. Photoluminescence data indicate that Ga-doped CdSe thin films display a deep level band at the lowest peak intensity, which is the indication of less defected structure. All the samples exhibit n-type conductivity. Additionally, the maximum carrier density and the minimum resistivity are reached for In-doped CdSe thin films as 1.75 x 10(16) cm(-3) and 6.12 & omega; cm, respectively. Rise time of 28 ms and fall time of 25 ms are obtained for Cu-doped CdSe thin films-based photodetector, which are the fastest photoresponse within all the devices. Furthermore, Cu-doped CdSe thin films-based device has a responsivity of 1.20 x 10(-2) A/W and a detectivity of 1.20 x 10(9) Jones that makes Cu-doped CdSe thin films-based device as a strong candidate for high sensitive photodetector applications.Öğe CdSe thin films-based photodetector doped with Cu, In and Ga atoms: a comparative work(Springer Heidelberg, 2023) Yilmaz, S.; Polat, I.; Tomakin, M.; Kucukomeroglu, T.; Bacaksiz, E.The present work demonstrates a comparison of performance of Cu, In and Ga-doped CdSe thin films-based photodetectors. Structural, morphological, optical and electrical investigation of Cu, In and Ga-doped CdSe thin films prepared by close space sublimation on glass slides is also achieved. It is obtained that Cu, In and Ga-doped CdSe thin films have a good crystal quality with a hexagonal structure in the preferred orientation along (002) plane. Morphological examination shows that Cu-doped CdSe thin films grow in the porous microstructure while In and Ga-doped CdSe films possess compact and uniform morphology without any voids. Transparency of In and Ga-doped CdSe films are higher than that of Cu-doped CdSe throughout the entire spectrum. Band gap values of all the samples are determined to be almost 1.72 eV. Photoluminescence data indicate that Ga-doped CdSe thin films display a deep level band at the lowest peak intensity, which is the indication of less defected structure. All the samples exhibit n-type conductivity. Additionally, the maximum carrier density and the minimum resistivity are reached for In-doped CdSe thin films as 1.75 x 10(16) cm(-3) and 6.12 & omega; cm, respectively. Rise time of 28 ms and fall time of 25 ms are obtained for Cu-doped CdSe thin films-based photodetector, which are the fastest photoresponse within all the devices. Furthermore, Cu-doped CdSe thin films-based device has a responsivity of 1.20 x 10(-2) A/W and a detectivity of 1.20 x 10(9) Jones that makes Cu-doped CdSe thin films-based device as a strong candidate for high sensitive photodetector applications.Öğe Comparative studies of CdS, CdS:Al, CdS:Na and CdS:(Al-Na) thin films prepared by spray pyrolysis(Academic Press Ltd- Elsevier Science Ltd, 2015) Yilmaz, S.; Atasoy, Y.; Tomakin, M.; Bacaksiz, E.In the present study, the spray pyrolysis technique was used to prepare pure CdS, 4 at.% Al-doped CdS, 4 at.% Na-doped CdS and (4 at.% Al, 4 at.% Na)-co-doped CdS thin films. It was found from X-ray diffraction data that all the specimens showed hexagonal wurtzite structure with the preferred orientation of (101). Scanning electron microscopy results indicated that 4 at.% Al-doping caused a grain growth in the morphology of CdS thin films whereas the 4 at.% Na-doping and (4 at.% Al, 4 at.% Na)-co-doping led to porous structure with small grains. The band gap value of CdS thin films increased to 2.42 eV after 4 at.% Al-doping. However, it reduced to 2.30 eV and 2.08 eV for 4 at.% Na-doping and (4 at.% Al, 4 at.% Na)-co-doping, respectively. The room temperature photoluminescence measurements illustrated that the peak intensity of CdS thin films enhanced with 4 at.% Al-doping while 4 at.% Na-doping and (4 at.% Al, 4 at.% Na)-co-doping caused a decline in the intensity. The maximum carrier concentration and minimum resistivity were obtained for 4 at.% Al-doped CdS thin films, which is associated with the grain growth. Furthermore, (4 at.% Al, 4 at.% Na)-co-doping gave rise to a slight reduction in the carrier concentration and a slight increment in the resistivity. As a result, it can be said that 4 at.% Al-doped CdS thin films exhibited the best electrical and optical properties, which is important for the optoelectronic applications. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Comparative studies of CdS, CdS:Al, CdS:Na and CdS:(Al-Na) thin films prepared by spray pyrolysis(Academic Press Ltd- Elsevier Science Ltd, 2015) Yilmaz, S.; Atasoy, Y.; Tomakin, M.; Bacaksiz, E.In the present study, the spray pyrolysis technique was used to prepare pure CdS, 4 at.% Al-doped CdS, 4 at.% Na-doped CdS and (4 at.% Al, 4 at.% Na)-co-doped CdS thin films. It was found from X-ray diffraction data that all the specimens showed hexagonal wurtzite structure with the preferred orientation of (101). Scanning electron microscopy results indicated that 4 at.% Al-doping caused a grain growth in the morphology of CdS thin films whereas the 4 at.% Na-doping and (4 at.% Al, 4 at.% Na)-co-doping led to porous structure with small grains. The band gap value of CdS thin films increased to 2.42 eV after 4 at.% Al-doping. However, it reduced to 2.30 eV and 2.08 eV for 4 at.% Na-doping and (4 at.% Al, 4 at.% Na)-co-doping, respectively. The room temperature photoluminescence measurements illustrated that the peak intensity of CdS thin films enhanced with 4 at.% Al-doping while 4 at.% Na-doping and (4 at.% Al, 4 at.% Na)-co-doping caused a decline in the intensity. The maximum carrier concentration and minimum resistivity were obtained for 4 at.% Al-doped CdS thin films, which is associated with the grain growth. Furthermore, (4 at.% Al, 4 at.% Na)-co-doping gave rise to a slight reduction in the carrier concentration and a slight increment in the resistivity. As a result, it can be said that 4 at.% Al-doped CdS thin films exhibited the best electrical and optical properties, which is important for the optoelectronic applications. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Defect-mediated ferromagnetism in ZnO:Mn nanorods(Springer, 2014) Yilmaz, S.; McGlynn, E.; Bacaksiz, E.; Bogan, J.In this work, the structural, chemical and magnetic properties of ZnO:Mn nanorods were investigated. Firstly, well-aligned ZnO nanorods with their long axis parallel to the crystalline c-axis were successfully grown by the vapor phase transport technique on Si substrates coated with a ZnO buffer layer. Mn metal was then diffused into these nanorods at different temperatures in vacuum. From SEM results, ZnO:Mn nanorods were observed to have diameters of similar to 100 nm and lengths of 4 mu m. XPS analysis showed that the Mn dopant substituted into the ZnO matrix with a valence state of +2. Magnetic measurements performed at room temperature revealed that undoped ZnO nanorods exhibit ferromagnetic behavior which may be related to oxygen vacancy defect-mediated d (0) ferromagnetism. ZnO:Mn samples were seen to show an excess room temperature ferromagnetism that is attributed to the presence of oxygen vacancy defects forming bound magnetic polarons involving Mn.Öğe Determination of optimum Er-doping level to get high transparent and low resistive Cd1-xErxS thin films(Springer, 2019) Yilmaz, S.; Polat, I.; Tomakin, M.; Bacaksiz, E.Cd1-xErxS (x=0, 0.02, 0.04, 0.06, 0.08 and 0.10) thin films were produced by a chemical route on glass slides. The structural, morphological, optical and electrical properties of the grown samples were studied to obtain the optimum Er-doping level. Structural properties indicated that specimens had a hexagonal structure. Morphological analysis showed that the grain size of pristine CdS thin films remarkably reduced with rising Er-doping. The presence of Er atoms in CdS host structure was proved by energy dispersive of X-ray spectroscopy (EDS). The transparency of CdS thin films substantially improved after 10at.% Er-doping and a gradual decrease was acquired in the band gaps of the CdS samples with the increase of Er-doping. Photoluminescence data approved the existence of two main peaks corresponding to the green and yellow regions. Electrical properties of pristine CdS thin films were enhanced by Er-doping and the best electrical conclusions were obtained for Cd0.94Er0.06S thin films. Thus, it can be brought to an end that Er-doping enhanced both optical and electrical properties of pristine CdS thin films, which are of vital importance in optoelectronic applications.Öğe Development of photovoltaic and photodetection characteristics in CdS/ P3HT devices through Al-doping(Elsevier, 2024) Toreli, S. B.; Yilmaz, S.; Tomakin, M.; Polat, I; Bacaksiz, E.CdS thin films were deposited by chemical bath deposition onto FTO substrates with Al concentrations of 0, 1, 3, 5 and 6 %. X-ray diffraction revealed introduction of 1 % Al-doping reduced dislocation density and enhanced the crystal quality of CdS. Scanning electron microscopy confirmed a reduction in grain size in Al-doped CdS films compared to CdS. N3 and P3HT layers were spin-coated onto the prepared substrates, respectively. The fabrication of the solar cells was completed using Ag silver paste for the top contact. The lowest photoluminescence peak intensity was achieved for CdS (3 %Al):P3HT solar cell, indicating efficient exciton dissociation. 3 % Al-doped CdS-based device exhibited the highest efficiency at 0.210 %, nearly seven times that of reference device. CdS (3 %Al):P3HT device demonstrated the best photodetection characteristics, with a responsivity of 2.2 x 10-2-2 A/W, detectivity of 3.3 x 108 8 Jones, response time of 13 ms, and recovery time of 12 ms at zero bias voltage.Öğe Development of photovoltaic and photodetection characteristics in CdS/ P3HT devices through Al-doping(Elsevier, 2024) Toreli, S. B.; Yilmaz, S.; Tomakin, M.; Polat, I; Bacaksiz, E.CdS thin films were deposited by chemical bath deposition onto FTO substrates with Al concentrations of 0, 1, 3, 5 and 6 %. X-ray diffraction revealed introduction of 1 % Al-doping reduced dislocation density and enhanced the crystal quality of CdS. Scanning electron microscopy confirmed a reduction in grain size in Al-doped CdS films compared to CdS. N3 and P3HT layers were spin-coated onto the prepared substrates, respectively. The fabrication of the solar cells was completed using Ag silver paste for the top contact. The lowest photoluminescence peak intensity was achieved for CdS (3 %Al):P3HT solar cell, indicating efficient exciton dissociation. 3 % Al-doped CdS-based device exhibited the highest efficiency at 0.210 %, nearly seven times that of reference device. CdS (3 %Al):P3HT device demonstrated the best photodetection characteristics, with a responsivity of 2.2 x 10-2-2 A/W, detectivity of 3.3 x 108 8 Jones, response time of 13 ms, and recovery time of 12 ms at zero bias voltage.Öğe Enhancement in the optical and electrical properties of CdS thin films through Ga and K co-doping(Elsevier Sci Ltd, 2017) Yilmaz, S.; Toreli, S. B.; Polat, I.; Olgar, M. A.; Tomakin, M.; Bacaksiz, E.In the presented work, Ga-doped CdS and (Ga-K)-co-doped CdS thin films are grown on glass substrates at a temperature of 400 degrees C through spray pyrolysis. Influence of K-doping on structural, morphological, optical and electrical characteristics of CdS:Ga thin films are examined. K level is changed from 1 at% to 5 at% for CdS:Ga samples just as Ga concentration is fixed 2 at% for all CdS thin films. It is observed from the X-ray diffraction data that all the samples exhibit hexagonal structure and an increase level of K in Ga-doped CdS samples causes a degradation in the crystal quality. Energy-dispersive X-ray spectroscopy measurements illustrate that the best stoichiometric film is acquired when K content is 2 at% in Ga-doped CdS films. Optical transmission curves demonstrate that CdS:Ga thin films exhibit the best optical transparency in the visible range for 4 at% K content compared to other specimens. A widening in the optical bandgap is unveiled after K-dopings. It is obtained that maximum band gap value is found as 2.45 eV for 3 at%, 4 at% and 5 at%. K -dopings while Ga-doped CdS thin films display the band gap value of 2.43 eV. From photoluminescence measurements, the most intensified peak is observed in the deep level emission after incorporation of the 4 at% K atoms. As for electrical characterization results, the resistivity reduces and the carrier density improves with the increase of K concentration from 1 at% to 4 at%. Based on all the data, it can be deduced that 4 at% K-doped CdS:Ga thin films show the best optical and electrical behavior, which can be utilized for solar cell devices.Öğe Enhancement in the optical and electrical properties of CdS thin films through Ga and K co-doping(Elsevier Sci Ltd, 2017) Yilmaz, S.; Toreli, S. B.; Polat, I.; Olgar, M. A.; Tomakin, M.; Bacaksiz, E.In the presented work, Ga-doped CdS and (Ga-K)-co-doped CdS thin films are grown on glass substrates at a temperature of 400 degrees C through spray pyrolysis. Influence of K-doping on structural, morphological, optical and electrical characteristics of CdS:Ga thin films are examined. K level is changed from 1 at% to 5 at% for CdS:Ga samples just as Ga concentration is fixed 2 at% for all CdS thin films. It is observed from the X-ray diffraction data that all the samples exhibit hexagonal structure and an increase level of K in Ga-doped CdS samples causes a degradation in the crystal quality. Energy-dispersive X-ray spectroscopy measurements illustrate that the best stoichiometric film is acquired when K content is 2 at% in Ga-doped CdS films. Optical transmission curves demonstrate that CdS:Ga thin films exhibit the best optical transparency in the visible range for 4 at% K content compared to other specimens. A widening in the optical bandgap is unveiled after K-dopings. It is obtained that maximum band gap value is found as 2.45 eV for 3 at%, 4 at% and 5 at%. K -dopings while Ga-doped CdS thin films display the band gap value of 2.43 eV. From photoluminescence measurements, the most intensified peak is observed in the deep level emission after incorporation of the 4 at% K atoms. As for electrical characterization results, the resistivity reduces and the carrier density improves with the increase of K concentration from 1 at% to 4 at%. Based on all the data, it can be deduced that 4 at% K-doped CdS:Ga thin films show the best optical and electrical behavior, which can be utilized for solar cell devices.Öğe Fabrication of CdS nanospheres-based hybrid solar cells having increased efficiency(Springer Heidelberg, 2022) Yilmaz, S.; Unverdi, A.; Tomakin, M.; Polat, I.; Bacaksiz, E.The impact of surface modification through diverse dyes (Eosin-Y, D205, N719 and N3) on structural, morphological, optical, and electrical properties of CdS/P3HT hybrid solar cells is studied. X-ray diffraction (XRD) pattern shows that CdS nanospheres have a hexagonal structure with a preferential orientation of (002) with respect to indium tin oxide (ITO) coated glass slide. Scanning electron microscopy (SEM) results indicate that compact and dense spherical morphologies of CdS occurred, and the P3HT layer also consisted of small spherical grains. The bandgap of CdS is found to be 2.52 eV according to Tauc's plot analysis. Absorption spectra demonstrate that interfacial modification via each dye leads to an increase in the absorption in the wavelength range of 300-1000 nm. Photoluminescence (PL) data prove that surface modification of CdS nanospheres with diverse dyes causes a decrease in the spectral intensity of PL curve, implying that efficient exciton separation is taking place upon dye loadings. Fabricated devices with and without modification show photovoltaic effects that can be seen from current density-voltage (J-V) curves obviously, and the highest power conversion efficiency (PCE) is obtained as 0.881% for N719-modified (ITO/CdS/N719/P3HT/Ag) device (almost 70-fold of pristine one) with a short-circuit current density (J(sc)) of 2.878mA/cm(2) and open-circuit voltage (V-oc) of 0.92V, respectively. This enhancement can be attributed to a better surface area between CdS and P3HT after dye modification.Öğe Fabrication of CdS nanospheres-based hybrid solar cells having increased efficiency(Springer Heidelberg, 2022) Yilmaz, S.; Unverdi, A.; Tomakin, M.; Polat, I.; Bacaksiz, E.The impact of surface modification through diverse dyes (Eosin-Y, D205, N719 and N3) on structural, morphological, optical, and electrical properties of CdS/P3HT hybrid solar cells is studied. X-ray diffraction (XRD) pattern shows that CdS nanospheres have a hexagonal structure with a preferential orientation of (002) with respect to indium tin oxide (ITO) coated glass slide. Scanning electron microscopy (SEM) results indicate that compact and dense spherical morphologies of CdS occurred, and the P3HT layer also consisted of small spherical grains. The bandgap of CdS is found to be 2.52 eV according to Tauc's plot analysis. Absorption spectra demonstrate that interfacial modification via each dye leads to an increase in the absorption in the wavelength range of 300-1000 nm. Photoluminescence (PL) data prove that surface modification of CdS nanospheres with diverse dyes causes a decrease in the spectral intensity of PL curve, implying that efficient exciton separation is taking place upon dye loadings. Fabricated devices with and without modification show photovoltaic effects that can be seen from current density-voltage (J-V) curves obviously, and the highest power conversion efficiency (PCE) is obtained as 0.881% for N719-modified (ITO/CdS/N719/P3HT/Ag) device (almost 70-fold of pristine one) with a short-circuit current density (J(sc)) of 2.878mA/cm(2) and open-circuit voltage (V-oc) of 0.92V, respectively. This enhancement can be attributed to a better surface area between CdS and P3HT after dye modification.Öğe Facile synthesis and characterization of CdS thin films doped by yttrium atoms(Springer Heidelberg, 2023) Yilmaz, S.; Tomakin, M.; Polat, I.; Bacaksiz, E.A facile preparation and structural, optical and electrical characterization of undoped and Y-doped CdS thin films are demonstrated through spray pyrolysis changing doping concentration of yttrium atoms in CdS structure. X-ray diffraction pattern displays that CdS samples have polycrystalline hexagonal phase and as they are doped by various amounts of Y atoms, a fluctuation is observed in the preferential orientation. Scanning electron microscopy results show that compact and smooth surface morphology in addition to a slight reduction in grain size are obtained with increasing Y-doping up to 5%. Transparency of CdS thin films are noticeably enhanced by doping of 1% Y atoms. However, further increase of Y-doping towards 5% causes less transparent CdS films due to deterioration of crystal quality. Tauc analysis indicates presence of two direct bandgaps for each sample owing to spin-orbit splitting of valence band of CdS. CdS films have bandgaps of 2.48 eV (E-g1) and 2.85 eV (E-g2). Whereas E-g1 value decreases to 2.46 for 5% Y-doping, E-g2 value increases to 2.92 eV for the same Y-doping concentration. Photoluminescence data show that an obvious red shift is observed for blue band regardless of Y-doping concentration. 3% Y-doped CdS thin films display the best carrier density of 4.37 x 10(14) cm(-3) and resistivity of 3.78 x 10(3) & omega;.cm, which originate from substitutional incorporation of Y3+ ions at Cd2+ ions. Therefore, it can be stated that Y-doped CdS thin films exhibit better electrical and optical properties that are of vital importance in thin film-based solar cells as a window layer.Öğe Facile synthesis and characterization of CdS thin films doped by yttrium atoms(Springer Heidelberg, 2023) Yilmaz, S.; Tomakin, M.; Polat, I.; Bacaksiz, E.A facile preparation and structural, optical and electrical characterization of undoped and Y-doped CdS thin films are demonstrated through spray pyrolysis changing doping concentration of yttrium atoms in CdS structure. X-ray diffraction pattern displays that CdS samples have polycrystalline hexagonal phase and as they are doped by various amounts of Y atoms, a fluctuation is observed in the preferential orientation. Scanning electron microscopy results show that compact and smooth surface morphology in addition to a slight reduction in grain size are obtained with increasing Y-doping up to 5%. Transparency of CdS thin films are noticeably enhanced by doping of 1% Y atoms. However, further increase of Y-doping towards 5% causes less transparent CdS films due to deterioration of crystal quality. Tauc analysis indicates presence of two direct bandgaps for each sample owing to spin-orbit splitting of valence band of CdS. CdS films have bandgaps of 2.48 eV (E-g1) and 2.85 eV (E-g2). Whereas E-g1 value decreases to 2.46 for 5% Y-doping, E-g2 value increases to 2.92 eV for the same Y-doping concentration. Photoluminescence data show that an obvious red shift is observed for blue band regardless of Y-doping concentration. 3% Y-doped CdS thin films display the best carrier density of 4.37 x 10(14) cm(-3) and resistivity of 3.78 x 10(3) & omega;.cm, which originate from substitutional incorporation of Y3+ ions at Cd2+ ions. Therefore, it can be stated that Y-doped CdS thin films exhibit better electrical and optical properties that are of vital importance in thin film-based solar cells as a window layer.
