Renewable Energy Resources and Technologies
Mohammad Reza Shekari; Seyed Mohammad Sadeghzadeh; Mahdi Golriz
Abstract
In recent decade, Perovskite Solar Cells (PSCs) have received considerable attention compared to other photovoltaic technologies. Despite the improvement of Power Conversion Efficiency (PCE) of PSCs, the chemical instability problem is still a matter of challenge. In this study, we have fabricated two ...
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In recent decade, Perovskite Solar Cells (PSCs) have received considerable attention compared to other photovoltaic technologies. Despite the improvement of Power Conversion Efficiency (PCE) of PSCs, the chemical instability problem is still a matter of challenge. In this study, we have fabricated two kinds of PSCs based on gold and carbon electrodes with the optimal PCE of about 15 % and 10.2 %, respectively. We prepared a novel carbon electrode using carbon black nanopowder and natural graphite flaky powder for Hole Transport Material (HTM) free carbon-based PSC (C-PSC). Current density-voltage characteristics over time were measured to compare the stability of devices. Scanning Electron Microscope (SEM) and Energy-dispersive X-ray Spectroscopy (EDS) analyses were carried out to study applied materials, layer, and surface structures of the cells. The crystal structure of perovskite and its association with the stability of PSCs were analyzed using an obtained X-ray diffraction (XRD) pattern. As a result, the constructed HTM-free C-PSC demonstrated high stability against air, retaining up to 90 % of its optimal efficiency after 2000 h in the dark under ambient conditions (relative humidity of (50 ± 5); average room temperature of 25 °C) in comparison to constructed gold-based PSCs (Gold-PSC) which are not stable at times. The experimental results show that novel low-cost and low-temperature carbon electrode could represent a wider prospect of reaching better stability for PSCs in the future.
Masood Mehrabian; Sonya Aslyousefzadeh
Abstract
Zinc oxide nanorod arrays (ZnO NRs) were grown on the ZnO seed layers via an aqueous solution using hydrothermal method and their photovoltaic properties were investigated. It was found that the growth period of 20 minutes is the optimum condition for ZnO nanorods growth, the cell containing these nanorods ...
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Zinc oxide nanorod arrays (ZnO NRs) were grown on the ZnO seed layers via an aqueous solution using hydrothermal method and their photovoltaic properties were investigated. It was found that the growth period of 20 minutes is the optimum condition for ZnO nanorods growth, the cell containing these nanorods was considered as a reference cell. In order to further increase the cell performance, ZnS quantum dots (QDs) were fabricated on the ZnO NRs (reference cell) by SILAR technique with different number of cycles. The effect of the number of SILAR cycle (n) on structural and photovoltaic properties was studied. The optimum number of SILAR cycles for ZnS QDs was obtained (n=4). Experimental results showed that using ZnS QDs as light absorber material is an effective way to improve device performance. Morphology, crystalline structure and optical absorption of layers were analyzed by a scanning electron microscope (SEM), X-ray diffraction (XRD) and UV-Visible absorption spectra, respectively. The maximum power conversion efficiency of 3.59% in the inverted configuration of ITO/ZnO film/ZnO NR(20)/ZnS(n) QDs/P3HT/PCBM/Ag hybrid solar cell was achieved for a device based on ZnS(4) under an illumination of one Sun (AM 1.5G, 100 mW/cm2)
Mahmoud Samadpour; Mehdi Molaei
Abstract
CdSe quantum dots were in situ deposited on various structures of TiO2 photoanode by successive ionic layer adsorption and reaction (SILAR). Various sensitized TiO2 structures were integrated as a photoanode in order to make quantum dot sensitized solar cells. High power conversion efficiency was obtained; ...
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CdSe quantum dots were in situ deposited on various structures of TiO2 photoanode by successive ionic layer adsorption and reaction (SILAR). Various sensitized TiO2 structures were integrated as a photoanode in order to make quantum dot sensitized solar cells. High power conversion efficiency was obtained; 2.89 % (Voc=524 mV, Jsc=9.78 mA/cm2, FF=0.56) for the cells that sensitized by SILAR method. Also all the cells, showed rather high efficiencies (more than 2.65%) regardless of their structure. Here we did the SILAR deposition in room temperature by a simple method which introduces it as a cost effective method for large scale production. Regarding the considerable efficiencies which obtained here by simple SILAR method for various structures, pointed out that SILAR deposition, can be introduced as an effective method for sensitizing electrodes by QDs, in quantum dot sensitized solar cells.
