Yazar "Yasar, S." seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim
    Öğe
    Improved characteristics for chemically grown Cu2SnS3 promising solar absorbers through the use of TritonX-100® surfactant
    (Elsevier Science Sa, 2015) Yasar, S.; Kahraman, S.; Cetinkaya, S.; Bilican, I.
    In this paper, we report, for the first time, the results of the TritonX-100 (R) surfactant assisted growth of Cu2SnS3 thin films obtained by using sol-gel spin coating method and a subsequent annealing in a sulfur atmosphere. Structural, morphological, compositional, photo-electrical investigations have been carried out. X-ray diffraction patterns of the samples matched well with the reference Cu2SnS3 pattern and indicated the polycrystalline nature of the films. Crystallite size of the films increased whereas surface roughness of the films decreased with increasing Triton-X100 (R) content. The surface of the samples has been smoother with Triton-X100 (R) inclusion. The photo-sensitivity of the n-Si/CTS structures has been confirmed through photo-transient current measurements. An increment was observed in the photoinduced current values of the samples with increasing Triton-X100 (R) content and was attributed to transport of photo-induced electrons facilitated with decreasing recombination resulted from the surface enhancement of the films. Electrical conduction mechanism of the films was investigated with resistance-temperature measurements. It has been revealed that TritonX-100 (R) surfactant assisted growth is a promising way to improve conversion efficiency of Cu2SnS3 based solar cells. (C) 2014 Elsevier B.V. All rights reserved.
  • Küçük Resim
    Öğe
    Numerical thickness optimization study of CIGS based solar cells with wxAMPS
    (Elsevier Gmbh, 2016) Yasar, S.; Kahraman, S.; Cetinkaya, S.; Apaydin, S.; Bilican, I.; Uluer, I.
    In this paper, a numerical investigation of the effects of thickness of absorber and buffer layers for a typical CIGS based solar cell was carried out for the first time, employing the wxAMPS software which is a new custom-designed software package for solar cell simulation. We have examined how the output parameters change with absorber and buffer thicknesses and suggested four different cell structures. By using the baseline structure, an optimum band gap value of 1.4 eV was determined for the CIGS absorber layer prior to do thickness study. Optimum absorber thickness value has been determined as 2500 nm from the simulation results. Spectral response of the cell decreased with increasing thickness in blue region. The influence of buffer layer thickness was investigated and it was found that most of the photo-generated carriers are collected by a thinner CdS layer. A significant decrease in current density, open circuit voltage and conversion efficiency occurred with increasing buffer layer thickness. This behavior was attributed to a decrease in the number of collected carriers due to the recombination of electron-hole pairs proceeded from the absorbed photons in the CdS bulk for large thickness. As a result, efficiencies around 27% were obtained through optimization while that of baseline structure was 25%. Our results have shown that the suggested structures both produce higher efficiencies than that of baseline structure and may lead to produce more efficient CIGS-based thin film solar cells. (C) 2016 Elsevier GmbH. All rights reserved.
  • Küçük Resim
    Öğe
    Polyethylene glycol-assisted growth of Cu2SnS3 promising absorbers for thin film solar cell applications
    (Taylor & Francis Ltd, 2014) Kahraman, S.; Cetinkaya, S.; Yasar, S.; Bilican, I.
    In this paper, we report, for the first time, the results of the polyethylene glycol- (PEG) assisted preparation and characterization of high-quality and well-crystallized Cu2SnS3 (CTS) thin films obtained using sol-gel spin-coating method and a subsequent annealing in a sulphur atmosphere. Structural, morphological, compositional, electrical and optical investigations were carried out. The X-ray diffraction patterns of the samples proved the polycrystalline nature and preferred crystallization of the films. No peak referring to other binary or ternary phases were detected in the patterns. The intensity of the preferred orientation and crystallite size of the films increased with increasing PEG content. This trend yielded an improvement in photo-transient currents of the PEG-assisted growth of CTS films. The scanning electron microscopy images revealed that the CTS films have continuous, dense and agglomeration-like morphology. Through energy dispersive X-ray spectroscopy studies, it has been deduced that the samples consist of Cu, Sn and S of which atomic percentages were consistent with Cu/Sn and S/metal initial ratios. The agglomerated morphology of the samples has been attributed to increasing PEG content. A remarkable enhancement was observed in photo-transient currents of p-n junction of the produced films along with increasing PEG content. Through resistivity-temperature measurements, three impurity level electrical activation energy values for each film were found. Optical band gap values of the films were estimated via absorbance-wavelength behaviours and decreased with increasing PEG content. It has been revealed that PEG-assisted growth of CTS thin films is a promising way to improve its photovoltaic characteristics.