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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 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 Improving photovoltaic characteristics of CdS-based hybrid solar cells through Mn incorporation(Elsevier Science Sa, 2024) Dogan, V.; Yilmaz, S.; Tomakin, M.; Toreli, S. B.; Polat, I; Bacaksiz, E.CdS thin films, both with and without Mn-doping, were grown via chemical bath deposition on indium tin oxidecoated glass substrates for application in hybrid solar cells. X-ray diffraction analysis revealed that Mn doping led to a deterioration in the crystal quality of CdS samples, evidenced by increased microstrain and dislocation density. Mn atoms were interstitially incorporated into the CdS structure, resulting in an expansion of the unit cell volume. Morphological analysis indicated a decrease in grain size from 390 nm to 140 nm for 0 % and 2 % Mn-doped CdS samples, respectively, while maintaining the spherical shape of the CdS thin films. Mn doping also increased the transmittance of CdS thin films, with the highest transparency of 95 % at 580 nm achieved for the 2 % Mn-doped CdS sample. In comparison to undoped CdS (2.38 eV), the band gap of CdS samples initially decreased to 1.84 eV for 1 % Mn doping but significantly increased to 3.03 eV for 2 % Mn-doped CdS. Photoluminescence (PL) data indicated that 2 % Mn-doped CdS thin films exhibited the lowest peak intensity, suggesting that a high concentration of Mn atoms caused non -radiative charge recombination. Additionally, efficient exciton dissociation was observed between CdS:Mn and P3HT:PCBM (poly(3-hexylthiophene) (P3HT) and [6,6]phenyl C61 -butyric acid methyl ester (PCBM)) layers in the 2 % Mn-doped CdS-based device, as per the PL results. Photovoltaic measurements demonstrated that compared to undoped CdS, 2 % Mn doping increased the power conversion efficiency of the CdS-based device from 0.070 % to 0.202 %, indicating an almost threefold increase in hybrid solar cell efficiency. This improvement is likely attributed to the development of a better interface between the CdS:Mn and P3HT:PCBM layers.Öğe Introduction of Co atoms into CdS thin films for improving photovoltaic properties(Elsevier, 2024) Yilmaz, S.; Dogan, V.; Tomakin, M.; Toreli, S. B.; Polat, I; Bacaksiz, E.This paper represents a systematic work on the fabrication of chemical bath -grown CdS films with and without Co atoms and their photovoltaic performances in hybrid solar cells. Structural properties showed 1% Co -doping promoted crystal quality of CdS films. However, a poor crystal quality was developed above 3% Co concentrations. A reduction in sphere size of CdS samples was observed for 1% Co -doping which was ascribed to slow growth of film. Optical examination demonstrated CdS films with 1% Co -doping displayed the highest transparency of 85% in the visible and near -infrared regions, which were explained by the improvement of crystal quality. A maximum band gap of 2.43 eV was found for 1% Co -doped CdS films, whereas an increase in Co concentration to 7% led to a decline in the band gap of CdS that was attributed to sp-d exchange interaction. Photoluminescence data showed Co -doped CdS films had lower PL peak intensity than that of CdS, demonstrating a decrease in the number of intrinsic defects. Photovoltaic measurements displayed that the best efficiency of 0.488% was achieved for CdS-based device including 1% Co atoms, which were almost a seven -fold boost in overall efficiency compared to bare CdS-based device. The enhancement in power conversion efficiency originated from an increase in short-circuit current density of 1% Co -doped CdS-based photovoltaic cell.Öğe Optical and electrical optimization of dysprosium-doped CdS thin films(Springer, 2018) Yilmaz, S.; Polat, I.; Tomakin, M.; Toreli, S. B.; Kucukomeroglu, T.; Bacaksiz, E.As-grown and Dy-doped CdS thin films containing concentrations of 1, 2, 3, 4 and 5 at.% Dy atom were prepared via chemical spray route on glass substrates. The constructed thin films were searched through analyzing their structural, morphological, optical and electrical features. X-ray diffraction (XRD) surveys showed that as-grown and Dy-doped CdS thin films had hexagonal structure and the preferential orientation was along (101) plane for as-grown, 1 and 2 at.% Dy-dopings. But further dopings (3 and 4 at.%) caused more random orientation, especially for the case of 5 at.%, the preferred orientation changed to (002) plane. The crystallite size progressively lessened from 39 to 27 nm with increasing Dy-doping. The existence of a close relation between grain shape and the preferential orientation appeared as compared to micrographs of scanning electron microscopy with XRD data. 5 at.% Dy-doped CdS thin films possessed the best transmittance (over 80%) among all the samples. Except for 2 at.% Dy-doped CdS sample, the other samples had almost a band gap of 2.45 eV. Photoluminescence results revealed that more stoichiometric thin films were formed after Dy-incorporations. The outcomes of the electrical investigation evidenced that the best sample was 1 at.% Dy-doped CdS thin films since the lowest resistivity (6.35 x 10(3) abroken vertical bar cm) and highest carrier concentration (1.06 x 10(14) cm(-3)) were obtained for this specimen.Öğe Physical properties of CdS:Ga thin films synthesized by spray pyrolysis technique(Springer, 2017) Yilmaz, S.; Polat, I.; Olgar, M. A.; Tomakin, M.; Toreli, S. B.; Bacaksiz, E.This paper reports the investigation of physical properties of CdS:Ga thin films grown for the first time by a simple spray pyrolysis method as a function of Ga-doping level from 0 to 8 at.%. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive photoelectron spectroscopy, transmittance, photoluminescence, Hall effect and resistivity measurements are utilized to search for the structural, morphological, chemical, optical and electrical properties of as-prepared samples. XRD data confirm the presence of hexagonal structure with a strong (101) preferred orientation. SEM results show that the surface morphology varies significantly via Ga-doping, particularly 6 at.% doping level. Optical transparency is improved by the lower Ga-doping (2 and 4 at.%) whereas higher doping concentration (6 and 8 at.%) causes a poor transmission in the visible region. With respect to CdS (2.42 eV), the calculated band gap values at first enhances for 2 at.% Ga-doping and reaches to 2.43 eV. But, further increase in Ga-doping amount leads to a drop in the band gap value (2.39 eV) for 8 at.% Ga-doping. Electrical analyses display that 2 at.% Ga-doped CdS thin films exhibit a maximum carrier density and a minimum resistivity that are related to the substitutional incorporation of Ga3+ ions at Cd2+ ions. However, higher doping of Ga atoms into CdS gives rise to a gradual diminish in the carrier concentration and a rise in the resistivity. Based on all the data, it should be concluded that 2 at.% Ga-doped CdS thin films exhibit the best optical and electrical properties that can be used in the optoelectronic applications.Öğe Sm-doped CdS thin films prepared by spray pyrolysis: a structural, optical, and electrical examination(Springer, 2018) Yilmaz, S.; Polat, I.; Tomakin, M.; Kucukomeroglu, T.; Toreli, S. B.; Bacaksiz, E.Virgin and Sm-doped CdS thin films were prepared by spray pyrolysis route on glass substrates. The influences of Sm-doping amount on structural, topographical, optical and electrical properties were examined. It was found from X-ray diffraction data that virgin and 1 and 2 at.% Sm-doped CdS samples grew along (002) plane whereas the preferred orientation changed to (101) starting from Sm doping of 3 at.%. Morphological investigation showed that even though CdS specimen had irregular shaped grains, Sm-doping substantially modified the surface topography of CdS thin films. A maximum transmittance were attained for 4 at.% Sm-doped CdS sample. After Sm-doping, a slight increase was observed in the band gap value of CdS thin films. It was found from the room temperature photoluminescence data that compared to the virgin CdS, the intrinsic defect population of Sm-doped CdS thin films reduced, meaning that more stoichiometric films formed. From the electrical measurements, it was determined that 1 at.% Sm-doped CdS thin films exhibited the best electrical properties, i.e., maximum carrier density and minimum resistivity. Based on all the data, it could be pronounced that 4 at.% Sm-doped CdS displayed the best optical properties, whereas the optimum electrical characteristics were reached for 1 at.% Sm-doped CdS thin films.
