Yazar "Tavakoli, Mohammad Mahdi" seçeneğine göre listele

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    Applications of carbon-based materials for ımproving the performance and stability of perovskite solar cells
    (John Wiley and Sons Inc., 2023) Patel, Krina; Prochowicz, Daniel; Akın, Seçkin; Kalam, Abul; Tavakoli, Mohammad Mahdi; Yadav, Pankaj
    Organic–inorganic hybrid perovskite solar cells (PSCs) attract many researchers in the field of photovoltaic because of their high-power conversion efficiency and low-cost manufacturing. However, improper interfacial charge transfer, perovskite degradation, and poor stability are major concerns for their commercialization and scale-up. Significant efforts have been made in recent years mainly by employing different strategies such as optimizing fabrication, developing novel materials, use of additives, and an interfacial layer in PSCs. Nowadays, carbon materials are widely recognized as promising candidates for alternative usage in PSCs because of their cost effectiveness, high conductivity, appropriate work function (5.0 eV), and low-temperature sintering process. In addition, the highly hydrophobic nature of the carbon-based materials prevents moisture penetration into the perovskite layer, resulting in enhanced stability. This review shows how effectively carbon-based materials can improve the performance of PSCs. First, the different carbon materials such as graphene and its derivatives, fullerenes and its derivatives, carbon quantum dots, and carbon nanotubes are described. Subsequently, the role of these carbon-based materials employed in electron-transport layers, hole-transport layers, and perovskite layers in PSCs is discussed. Thus, this review highlights the recent advancements made in carbon-based PSCs and their role in improving the performance of PSCs.
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    Efficient and less-toxic indium-doped mapbi(3) perovskite solar cells prepared by metal alloying technique
    (Wıley-V C H Verlag, 2022) Tavakoli, Mohammad Mahdi; Fazel, Ziba; Tavakoli, Rouhollah; Akın, Seçkin; Satapathi, Soumitra; Prochowicz, Daniel
    Perovskite materials with ABX(3) structure (A: organic, B: metal, and X: halides) have attracted tremendous attention due to their outstanding optoelectronic properties. Herein, a novel approach is developed using chemical vapor deposition (CVD), i.e., metal alloying of halide-perovskite domain via ion-transfer (MAHDI) for the growth of high-quality perovskite films, grown directly from a metal precursor. This technique easily enables us to replace the toxic Pb metal (B site) with other metals using alloying approach. Using the proposed approach, we fabricated stable and efficient Pb-In perovskite solar cells (PSCs) with a maximum power conversion efficiency (PCE) of 21.2%, which is more efficient than the pure Pb-based PSCs (19.23%). Our characterization results reveal that In-doping improves the crystallinity and photoluminescence (PL) of the perovskite film, resulting in higher photovoltaic properties in the device. To demonstrate the potential of our proposed method for other alloys, we also fabricated PSCs based on Pb-25%Sn alloy and obtained PCE of up to 15.2%. Overall, MAHDI technique opens up a new direction in the field of perovskite devices demonstrating great advantages such as lower price, higher performance, scalability, and fabrication flexibility.
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    Facile NaF Treatment Achieves 20% Efficient ETL-Free Perovskite Solar Cells
    (American Chemical Society, 2022) Sadegh, Faranak; Akman, Erdi; Prochowicz, Daniel; Tavakoli, Mohammad Mahdi; Yadav, Pankaj; Akın, Seçkin
    Electron transporting layer (ETL)-free perovskite solar cells (PSCs) exhibit promising progress in photovoltaic devices due to the elimination of the complex and energy-/time-consuming preparation route of ETLs. However, the performance of ETL-free devices still lags behind conventional devices because of mismatched energy levels and undesired interfacial charge recombination. In this study, we introduce sodium fluoride (NaF) as an interface layer in ETL-free PSCs to align the energy level between the perovskite and the FTO electrode. KPFM measurements clearly show that the NaF layer covers the surface of rough underlying FTO very well. This interface modification reduces the work function of FTO by forming an interfacial dipole layer, leading to band bending at the FTO/perovskite interface, which facilitates an effective electron carrier collection. Besides, the part of Na+ ions is found to be able to migrate into the absorber layer, facilitating enlarged grains and spontaneous passivation of the perovskite layer. As a result, the efficiency of the NaF-treated cell reaches 20%, comparable to those of state-of-the-art ETL-based cells. Moreover, this strategy effectively enhances the operational stability of devices by preserving 94% of the initial efficiency after storage for 500 h under continuous light soaking at 55 °C. Overall, these improvements in photovoltaic properties are clear indicators of enhanced interface passivation by NaF-based interface engineering. © 2022 American Chemical Society.
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    Investigation on the facet-dependent anisotropy in halide perovskite single crystals
    (American Chemical Society, 2022) Parikh, Nishi; Pandey, Manoj; Prochowicz, Daniel; Kalam, Abul; Tavakoli, Mohammad Mahdi; Satapathi, Soumitra; Akın, Seçkin; Yadav, Pankaj
    Metal halide perovskite (MHP) single crystals (SCs) are proven to possess superior optoelectronic properties compared to those of their polycrystalline thin film analogues. With the advancement and progress in the study of MHP SCs, it is found that the properties at the surface and bulk of SCs are significantly different. However, there are only a few studies present for the facet-dependent performance of MHP SCs. In this work, we have systematically investigated the anisotropic properties of naturally exposed facets ((100) and (112)) in MAPbI3 SCs. We studied the influence of temperature and illumination on the properties of these facets. It was found that hysteresis at the (112) facet is higher than that at the (100) facet because of the higher trap density of 1.17 × 1013 cm-3 at this facet as compared to the trap density of 2.11 × 1012 cm-3 for the (100) facet. Although there exist different kinds of defects at both the facets, the ion migration mechanism remains the same at both facets, which is confirmed by the obtained almost same activation energy of 0.378 and 0.308 eV for (100) and (112) facets, respectively, for ion migration. The photocurrent, responsivity, and EQE values further confirm anisotropic properties of both the facets in MAPbI3 SCs although they are the same from the crystallography point of view. Thus, this study provides a detailed and systematic investigation of the facet-dependent properties in MHP SCs.
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    Predicting the state parameters of lithium ion batteries: The race between filter-based and data driven approaches
    (Royal Society of Chemistry, 2023) Pandey, Siddhi Vinayak; Parikh, Nishi; Prochowicz, Daniel; Akın, Seçkin; Satapathi, Soumitra; Tavakoli, Mohammad Mahdi
    Lithium ion batteries (LIBs) have revolutionized the era of electrical energy storage by offering high energy density and longer life cycles in various applications such as electric vehicles, electronic gadgets, satellites and power grids. To achieve optimum and reliable performance throughout their life cycle, accurate monitoring of their state parameters such as state of charge (SOC), state of health (SOH), and remaining useful life (RUL) needs to be estimated precisely. Filter-based and data driven techniques estimate these parameters accurately even under dynamic battery operation. In this paper, first, we have given details about experimental techniques through which LIB state parameters are estimated, but due to poor nonlinearity handling capacity of these models, we showcase the potential of various filter-based and data driven techniques with a variety of features extracted from LIBs. Subsequently, we discuss the working and performance of various filter based and data driven algorithms utilised in predicting the state parameters of batteries such as SOC, SOH & RUL in detail. Additionally, a comparative table comprising features, predictive techniques and performance is made to highlight the effectiveness of each method. Finally, we propose a strategy to improve the estimation accuracy of LIBs. Overall, the paper provides a comprehensive review of various estimating lgorithms and their potential in predicting the state parameters of LIBs with an aim to develop an intelligent framework for required applications and highlights the challenges which are yet to be overcome.
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    Probing the surface and bulk electrical response of MAPbBr3Single crystals
    (American Chemical Society, 2022) Yadav, Pankaj; Parikh, Nishi; Prochowicz, Daniel; Kalam, Abul; Tavakoli, Mohammad Mahdi; Akın, Seçkin
    Single crystals (SCs) of halide perovskites are rapidly gaining attention over their polycrystalline thin-film counterparts due to their superior optoelectronic properties. One of the various reasons for their improved properties is the reduced defect concentration as compared with thin films. Since their discovery, many efforts have been devoted to discerning the surface and bulk properties of SCs. However, it is difficult to probe the surface and bulk responses of SCs, and only a few reports distinguishing between these properties have been presented. In this study, we distinguished between the surface and bulk electrical responses of methylammonium lead tribromide (MAPbBr3) SCs using impedance spectroscopy (IS). The electrical response of the MAPbBr3SC was recorded using different optical excitations for the generation of carriers. The Nyquist plots and capacitance-frequency responses observed under blue and red wavelengths differ significantly from each other and were studied systematically. The results obtained suggest that the photocurrent and capacitive response under blue light are higher than those under red light. Moreover, the change in the low-frequency capacitance is lower in the case of blue light. This is because of the polarization of the interface of metal contacts and the surface of SCs or due to defect-mediated conductivity. As the carriers are collected efficiently from the surface following a rapid process, they do not contribute to the capacitance build-up with temperature. To the best of our knowledge, electrical responses such as the impedance and the capacitive response of SCs using different illumination wavelengths and temperatures have been rarely discussed in the literature. © 2022 American Chemical Society. All rights reserved.
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    Rationalizing the effect of polymer-controlled growth of perovskite single crystals on optoelectronic properties
    (American Chemical Society, 2022) Parikh, Nishi; Sevak, Parth; Jowhar Khanam, Sarvani; Prochowicz, Daniel; Akın, Seçkin; Satapathi, Soumitra; Tavakoli, Mohammad Mahdi
    To improve and modulate the optoelectronic properties of single-crystal (SC) metal halide perovskites (MHPs), significant progress has been achieved. Polymer-assisted techniques are a great approach to control the growth rate of SCs effectively. However, the resultant optoelectrical properties induced by polymers are ambiguous and need to be taken into the consideration. In this study, we have synthesized methylammonium lead triiodide (MAPbI3) SCs using polyethylene glycol (PEG) and polystyrene (PS) polymers where PEG contains oxygen functionalities and PS does not. We studied the electrical properties of these SCs under dark and illumination conditions. It was observed that PEG-assisted SCs showed few defects with lower photocurrent as compared to the PS-assisted ones because of defect-mediated conductivity. The results are further verified by transient current response, responsivity, and capacitance-frequency measurements. The present study sheds light on the polymer selection for the growth of MHP SCs and their optoelectronic properties.