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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 Improved optical transparency of calcium-doped ZnO thin films(Natl Inst Optoelectronics, 2019) Polat, I; Yilmaz, S.; Tomakin, M.; Bacaksiz, E.ZnO thin films with various Ca-doping contents were produced by spray pyrolysis. X-ray diffraction results showed that all samples had a hexagonal structure. Morphological analysis indicated that all films had granular topography. The best transparency was obtained for 2 at.% Ca-doped ZnO samples. Band gap of ZnO thin films was found to be 3.22 eV and didn'tchange with increasing of Ca-doping. Photoluminescence data indicated that all samples had four emission peaks. Electrical measurements revealed that Ca-doping resulted in a gradual improvement of carrier density and consequently a decrement of resistivity, which is important for application areas in opto-electronics.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 Structural, morphological, optical analyses of Ni-doped CdS thin films and their photovoltaic performance in hybrid solar cells(Springer, 2020) Yilmaz, S.; Tomakin, M.; Unverdi, A.; Aydin, A.; Polat, I; Bacaksiz, E.This work reports influences of variation in Ni-doping on structural, morphological, and optical properties of CdS thin films and in their hybrid solar cell applications. X-ray diffraction data showed that increase of Ni-doping in CdS structure caused not only a broadening in CdS peak but also a decrease in the intensity of main cubic CdS peak. Morphological studies illustrated that lower amount of Ni-doping treatment firstly reduced the grain size of CdS thin films, whereas higher concentration of Ni-doping led to bigger grains. The best transparent CdS sample was achieved for 1 at% Ni-doping as 95% at 675 nm. Compared with CdS thin films (2.98 eV), bandwidths of Ni-doped CdS samples gradually increased and reached to 3.39 eV, which is due to the existence of strong quantum confinement effect. Photoluminescence (PL) data of the device demonstrated that the most efficient electron transfer was accomplished at CdS/P3HT interface for 1 at% Ni-doping because this device demonstrated the lowest PL peak intensity. Current density-voltage (J-V) characteristics of CdS-based device exhibited a power conversion efficiency (PCE) of 0.296% and it enhanced to 0.663% for device including 1 at% Ni atoms, which is most probably due to achievement of most efficient exciton dissociation between CdS and P3HT layers as approved by PL results. However, with increasing Ni-doping amount up to 3 at% and 5 at%, PCE values were in turn obtained as 0.131% and 0.208%, indicating a deterioration in PCE value of cells, which might be due to the less efficient exciton dissociation at the interface. Further increase of Ni-doping to 7 at% led to an efficiency value of 0.417%, which is still lower than that of 1 at% Ni-doped CdS-based device.
