Search for: photovoltaic-applications
Stable operation of grid connected Cascaded H-Bridge inverter under unbalanced insolation conditions, Article 2013 3rd International Conference on Electric Power and Energy Conversion Systems, EPECS 2013 2013 ; 2013 ; 9781479906888 (ISBN) ; Javadian, V ; Iman Eini, H ; Yadollahi, M ; Sharif University of Technology
This paper presents a single-phase Cascaded H-Bridge (CHB) inverter for photovoltaic applications. The proposed control strategy permits the optimum control of each string of PV panels in different insolation conditions. Based on the presented mathematical analysis, an analytic constraint is derived to check the stable operation of the inverter. A modified MPPT control strategy is also proposed based on this new condition. This strategy enhances the stability margins of the system by changing the operating point of some PV arrays. In this approach, the extracted power from high power cell is reduced to prevent instability issue and to avoid injection of highly distorted current into the...
Efficiency improvement of a high step up high efficiency converter for photovoltaic applications based on three-state switching cell, Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2013 , Pages 454-458 ; 9781467344845 (ISBN) ; Zolghadri, M. R ; Hajimoradi, M. R ; Sharif University of Technology
This paper suggests methods for improving efficiency of a high step up high efficiency converter based on three state commutation cells. A loss analysis has been performed to identify the source of power loss. Based on this analysis, methods are presented to reduce losses in the most power dissipating elements. These methods include replacing some power diodes with large conduction losses with MOSFETs having small on-state resistance. Efficiency improvement up to %1.25 percent is verified in simulation and experimental results
Article Journal of Physical Chemistry C ; Volume 119, Issue 33 , 2015 , Pages 18886-18895 ; 19327447 (ISSN) ; Aashuri, H ; Simchi, A ; Kalytchuk, S ; Fan, Z ; Sharif University of Technology
American Chemical Society 2015
Hybrid nanostructures combining semiconductor quantum dots and graphene are attracting increasing attention because of their optoelectronic properties promising for photovoltaic applications. We present a hot-injection synthesis of a colloidal nanostructure which we define as quasi core/shell PbS/graphene quantum dots due to the incomplete passivation of PbS surfaces with an ultrathin layer of graphene. Simulation by density functional theory of a prototypical model of a nonstoichiometric Pb-rich core (400 atoms) coated by graphene (20 atoms for each graphene sheet) indicates the possibility of surface passivation of (111) planes of PbS with graphene resulting in a decrease in trap states...
Surface engineering of pbs colloidal quantum dots using atomic passivation for photovoltaic applications, Article 8th International Conference on Materials for Advanced Technologies, 28 June 2015 through 3 July 2015 ; Volume 139 , 2016 , Pages 117-122 ; 18777058 (ISSN) ; Sharif University of Technology
Solution-processed quantum dots (QDs) have attracted significant attention for the low-cost fabrication of optoelectronic devices. Here, we synthesized PbS QDs via hot injection method and passivated the trap states by using short thiols and dopant elements for photovoltaic application. In order to study the effect of dopants on photovoltaic application, PbS QDs were doped by using three different cations: Cadmium, Calcium, and Zinc. We utilized Time resolvel Photoluminescence measurement to study the carriers lifetime for different samples and found that the carriers life time increases ∼80% by using Cd as a dopant compared with undoped sample. In addition, the results of J-V measurement...
Article IEEE Transactions on Industrial Electronics ; 2017 ; 02780046 (ISSN) ; Zolghadri, M. R ; Sharif University of Technology
In trasformerless grid-connected photovoltaic (PV) systems, common-mode voltage (CMV) fluctuations cause leakage current flow through the stray capacitance of the PV panels. Shoot-through (SH) states in a quasi-Z-source inverter (q-ZSI), increase the amplitude of high order harmonics of CMV. In this paper, by using the modulation technique based on odd PWM (OPWM) and minor change in the Z network of the three-phase q-ZSI, the leakage current is blocked. No extra semiconductor element is added. By the proposed technique, CMV is kept nearly constant during switching cycles. The experimental results for CMV analysis in a 1kW prototype are presented to verify the theoretical analysis. IEEE
Persistent quantum coherence and strong coupling enable fast electron transfer across the cds/tio2 interface: a time-domain ab initio simulation, Article Journal of Physical Chemistry C ; Volume 122, Issue 44 , 2018 , Pages 25606-25616 ; 19327447 (ISSN) ; Akimov, A. V ; Jankowska, J ; Rezakhanai, A. T ; Tafreshi, S. S ; De Leeuw, N. H ; Moshfegh, A. Z ; Prezhdo, O. V ; Sharif University of Technology
American Chemical Society 2018
Fast transfer of photoinduced electrons and subsequent slow electron-hole recombination in semiconductor heterostructures give rise to long-lived charge separation which is highly desirable for photocatalysis and photovoltaic applications. As a type II heterostructure, CdS/TiO2 nanocomposites extend the absorption edge of the light spectrum to the visible range and demonstrate effective charge separation, resulting in more efficient conversion of solar energy to chemical energy. This improvement in performance is partly explained by the fact that CdS/TiO2 is a type II semiconductor heterostructure and CdS has a smaller energy band gap than UV-active TiO2. Ultrafast transient absorption...
Article IEEE Transactions on Industrial Electronics ; Volume 65, Issue 6 , 2018 , Pages 4790-4798 ; 02780046 (ISSN) ; Zolghadri, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2018
In trasformerless grid-connected photovoltaic (PV) systems, common-mode voltage (CMV) fluctuations cause leakage current flow through the stray capacitance of the PV panels. Shoot-through states in a quasi-Z-source inverter (q-ZSI) increase the amplitude of high-order harmonics of CMV. In this paper, by using the modulation technique based on odd pulse width modulation and minor change in the Z network of the three-phase q-ZSI, the leakage current is blocked. No extra semiconductor element is added. By the proposed technique, CMV is kept nearly constant during switching cycles. The experimental results for CMV analysis in a 1kW prototype are presented to verify the theoretical analysis. ©...
Article Advanced Energy Materials ; Volume 8, Issue 12 , 2018 ; 16146832 (ISSN) ; Mazloum Ardakani, M ; Gholipour, S ; Marinova, N ; Delgado, J. L ; Turren Cruz, S. H ; Domanski, K ; Taghavinia, N ; Saliba, M ; Gratzel, M ; Hagfeldt, A ; Tress, W ; Sharif University of Technology
Wiley-VCH Verlag 2018
In the past few years, organic–inorganic metal halide ABX3 perovskites (A = Rb, Cs, methylammonium, formamidinium (FA); B = Pb, Sn; X = Cl, Br, I) have rapidly emerged as promising materials for photovoltaic applications. Tuning the film morphology by various deposition techniques and additives is crucial to achieve solar cells with high performance and long-term stability. In this work, carbon nanoparticles (CNPs) containing functional groups are added to the perovskite precursor solution for fabrication of fluorine-doped tin oxide/TiO2/perovskite/spiro-OMeTAD/gold devices. With the addition of CNPs, the perovskite films are thermally more stable, contain larger grains, and become more...
Oxygen plasma-induced p-type doping improves performance and stability of PbS quantum dot solar cells, Article ACS Applied Materials and Interfaces ; Volume 11, Issue 29 , 2019 , Pages 26047-26052 ; 19448244 (ISSN) ; Tavakoli, R ; Yadav, P ; Prochowicz, D ; Saliba, M ; Tavakoli, M. M ; Sharif University of Technology
American Chemical Society 2019
PbS quantum dots (QDs) have been extensively studied for photovoltaic applications, thanks to their facile and low-cost fabrication processing and interesting physical properties such as size dependent and tunable band gap. However, the performance of PbS QD-based solar cells is highly sensitive to the humidity level in the ambient air, which is a serious obstacle toward its practical applications. Although it has been previously revealed that oxygen doping of the hole transporting layer can mitigate the cause of this issue, the suggested methods to recover the device performance are time-consuming and relatively costly. Here, we report a low-power oxygen plasma treatment as a rapid and...
Development of nanostructured porous TiO2 thick film with uniform spherical particles by a new polymeric gel process for dye-sensitized solar cell applications, Article Electrochimica Acta ; Volume 89 , February , 2013 , Pages 90-97 ; 00134686 (ISSN) ; Mohammadi, M. R ; Sharif University of Technology
A novel simple synthetic procedure for fabrication of high surface area nanostructured TiO2 electrode with uniform particles for photovoltaic application is reported. Modifying the TiO2 particulate sol by pH adjustment together with employment of a polymeric agent, so-called polymeric gel process, was developed. The polymeric gel process was used to deposit nanostructured thick electrode by dip coating incorporated in dye-sensitized solar cells (DSSCs). X-ray diffraction (XRD) analysis revealed that deposited film was composed of primary nanoparticles with average crystallite size in the range 21-39 nm. Field emission scanning electron microscope (FE-SEM) images showed that deposited film...