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    Construction of perovskite solar cells using inorganic hole-extracting components

    , Article ACS Omega ; Volume 3, Issue 1 , 4 January , 2018 , Pages 46-54 ; 24701343 (ISSN) Nouri, E ; Mohammadi, M. R ; Lianos, P ; Sharif University of Technology
    American Chemical Society  2018
    A NiOx−graphene oxide (NiOx−GO) hybrid has been prepared by a simple solution-processed method and was used as hole-extraction material in perovskite solar cells with either gold or carbon as back contact electrode. The impact of GO content on the optoelectronic behavior of NiOx and the photovoltaic performance of the fabricated devices has been studied. Thus, GO incorporation showed a significant improvement in the performance of NiOx-based devices. The best attained efficiency was 13.3%, and it was 45% higher than that with pure NiOx. This is attributed to a significant improvement in the hole extraction, recombination resistance, and energy-level matching in comparison to pure NiOx. In... 

    Improvement of the photovoltaic parameters of perovskite solar cells using a reduced-graphene-oxide-modified titania layer and soluble copper phthalocyanine as a hole transporter

    , Article Physical Chemistry Chemical Physics ; Volume 20, Issue 4 , 2018 , Pages 2388-2395 ; 14639076 (ISSN) Nouri, E ; Mohammadi, M. R ; Xu, Z. X ; Dracopoulos, V ; Lianos, P ; Sharif University of Technology
    Royal Society of Chemistry  2018
    Functional perovskite solar cells can be made by using a simple, inexpensive and stable soluble tetra-n-butyl-substituted copper phthalocyanine (CuBuPc) as a hole transporter. In the present study, TiO2/reduced graphene oxide (T/RGO) hybrids were synthesized via an in situ solvothermal process and used as electron acceptor/transport mediators in mesoscopic perovskite solar cells based on soluble CuBuPc as a hole transporter and on graphene oxide (GO) as a buffer layer. The impact of the RGO content on the optoelectronic properties of T/RGO hybrids and on the solar cell performance was studied, suggesting improved electron transport characteristics and photovoltaic parameters. An enhanced... 

    Reducing surface recombination by a poly(4-vinylpyridine) interlayer in perovskite solar cells with high open-circuit voltage and efficiency

    , Article ACS Omega ; Volume 3, Issue 5 , 2018 , Pages 5038-5043 ; 24701343 (ISSN) Yavari, M ; Mazloum Ardakani, M ; Gholipour, S ; Tavakoli, M. M ; Taghavinia, N ; Hagfeldt, A ; Tress, W ; Sharif University of Technology
    American Chemical Society  2018
    Identifying and reducing the dominant recombination processes in perovskite solar cells is one of the major challenges for further device optimization. Here, we show that introducing a thin interlayer of poly(4-vinylpyridine) (PVP) between the perovskite film and the hole transport layer reduces nonradiative recombination. Employing such a PVP interlayer, we reach an open-circuit voltage of 1.20 V for the best devices and a stabilized efficiency of 20.7%. The beneficial effect of the PVP interlayer is proven by statistical analysis of various samples, many of those showing an open-circuit voltage larger than 1.17 V, and a 30 mV increase in average compared to unmodified samples. The reduced... 

    Coupled ionic-electronic equivalent circuit to describe asymmetric rise and decay of photovoltage profile in perovskite solar cells

    , Article Scientific Reports ; Volume 9, Issue 1 , 2019 ; 20452322 (ISSN) Ebadi, F ; Aryanpour, M ; Mohammadpour, R ; Taghavinia, N ; Sharif University of Technology
    Nature Publishing Group  2019
    In this research, we employed transient photo-voltage rise and decay measurements to investigate the origin of slow unsymmetrical rise and decay profiles in single and triple cation perovskite solar cells. Drastic changes in photo-voltage decay profile were observed upon insertion of Br−, Cs+ and FA+ ions into perovskite structures. In order to explain our observations, the activation energy for ionic defects was measured and an equivalent circuit model was proposed containing both electrical and ionic components. The electrical branch consists of a diode, the bulk capacitance and resistances for charge transport and recombination. In parallel we introduced an ionic branch describing the... 

    Modified antisolvent method for improving the performance and stability of triple-cation perovskite solar cells

    , Article ACS Omega ; Volume 6, Issue 1 , 2021 , Pages 172-179 ; 24701343 (ISSN) Samadpour, M ; Golchini, A ; Abdizadeh, K ; Heydari, M ; Forouzandeh, M ; Saki, Z ; Taghavinia, N ; Sharif University of Technology
    American Chemical Society  2021
    Antisolvent crystallization is known as an effective approach for the deposition of pinhole-free solution-processed perovskite layers for high-performance solar cells. Here, we introduce a modified antisolvent dripping method by adding tetra ethyl orthosilicate (TEOS) into chlorobenzene as a conventional antisolvent. Through TEOS modification, perovskite solar cells show efficiencies as high as 16% with more than 85% retention after 290 h storage at ambient conditions in comparison to 20% in pristine cells. This significant enhancement in efficiency and stability mainly related to the decrement of the density of surface defects, which is confirmed by considerably enhanced photoluminescence... 

    Quantum Well Solar Cell

    , M.Sc. Thesis Sharif University of Technology ZareBidaki, Homa (Author) ; Faez, Rahim (Supervisor)
    In this thesis, the goal is to improve the efficiency of quantum and solar cell. The effect of quantum wells was simulated by Silvaco. Initially, the quantum well has been adjusted to a cell junction GaAs. Then, using quantum wells in cell junction towing and three, improving short-circuit, the returns will be 53.79% and 54.33%. This efficiency is about 10% more than the triple-junction solar cells. To improve the efficiency effects of layer thicknesses, parameters, and the number of quantum wells were studied.Tandem cell is 〖In〗_0.51 〖Ga〗_0.49 P/GaAs, and triple is 〖In〗_0.51 〖Ga〗_0.49 P/GaAs/〖In〗_0.28 〖Ga〗_0.72 As. By adjusting the quantum well and sandwiching the well layers staggered by... 

    Recent developments in dye-sensitized solar cells

    , Article ChemPhysChem ; Vol. 15, issue. 18 , Dec , 2014 , p. 3902-3927 Sharifi, N ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
    The knowledge of dye-sensitized solar cells (DSCs) has expanded considerably in recent years. They are multiparameter and complex systems that work only if various parameters are tuned simultaneously. This makes it difficult to target to a single parameter to improve the efficiency. There is a wealth of knowledge concerning different DSC structures and characteristics. In this review, the present knowledge and recent achievements are surveyed with emphasis on the more promising cell materials and designs  

    Improved efficiency of dye-sensitized solar cells based on a single layer deposition of skein-like TiO 2 nanotubes

    , Article Journal of the American Ceramic Society ; Vol. 97, issue. 9 , 2014 , pp. 2873-2879 ; ISSN: 00027820 Mojaddami, M ; Mohammadi, M. R ; Madaah Hosseini, H. R ; Sharif University of Technology
    We present a new TiO2 morphology, featuring high surface area and open structure, synthesized by a two-step chemical route for the manufacture of dye-sensitized solar cells (DSSCs). This construct is sets of intertwined one-dimensional (1D) nanostructures (i.e., nanotubes), so-called skein-like nanotubes (NTs). Such morphology is produced by a combination of TiC oxidation and hydrothermal processes. The mesoporous TiO2 nanoparticles, as the product of TiC oxidation operation, is used as the precursor of hydrothermal process to grow the skein-like NTs. The effect of processing parameters of TiC oxidation and hydrothermal processes is studied. The skein-like morphology enables to eliminate the... 

    Double-Layer TiO2 Electrodes with Controlled Phase Composition and Morphology for Efficient Light Management in Dye-Sensitized Solar Cells

    , Article Journal of Cluster Science ; Vol. 25, issue. 4 , 2014 , p. 1029-1045 Abdi-Jalebi, M ; Mohammadi, M. R ; Fray, D. J ; Sharif University of Technology
    The light-scattering effect in the dye-sensitized solar cells (DSCs) was studied by controlling TiO2 phase composition and morphology by fabrication of double-layer cells with different arrangement modes. The starting material for preparation of TiO2 cells was synthesized by an aqueous sol-gel process. X-ray diffraction and field emission scanning electron microscopic analyses revealed that TiO2 nanoparticles had particle size ranging between 18 and 44 nm. The optical property and band gap energy of TiO2 nanoparticles were studied through UV-Vis absorption. The indirect optical band gap energy of anatase and rutile nanoparticles was found to be 3.47 and 3.41 eV, respectively. The... 

    Nanoparticulate hollow TiO 2 fibers as light scatterers in dye-sensitized solar cells: Layer-by-layer self-assembly parameters and mechanism

    , Article ChemPhysChem ; Volume 12, Issue 5 , 2011 , Pages 966-973 ; 14394235 (ISSN) Rahman, M ; Tajabadi, F ; Shooshtari, L ; Taghavinia, N ; Sharif University of Technology
    Hollow structures show both light scattering and light trapping, which makes them promising for dye-sensitized solar cell (DSSC) applications. In this work, nanoparticulate hollow TiO 2 fibers are prepared by layer-by-layer (LbL) self-assembly deposition of TiO 2 nanoparticles on natural cellulose fibers as template, followed by thermal removal of the template. The effect of LbL parameters such as the type and molecular weight of polyelectrolyte, number of dip cycles, and the TiO 2 dispersion (amorphous or crystalline sol) are investigated. LbL deposition with weak polyelectrolytes (polyethylenimine, PEI) gives greater nanoparticle deposition yield compared to strong polyelectrolytes... 

    Totally solution-processed CuInS2 solar cells based on chloride inks: Reduced metastable phases and improved current density

    , Article Journal of Physics D: Applied Physics ; Volume 48, Issue 11 , March , 2015 , pp. 115304-115311 ; 00223727 (ISSN) Dehghani, M ; Behjat, A ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
    Institute of Physics Publishing  2015
    Planar superstrate CuInS2 (CIS) solar cell devices are fabricated using totally solution-processed deposition methods. These Cd-free devices are structured by FTO/TiO2/In2S3/CIS/carbon, where TiO2 and In2S3 are deposited by spray pyrolysis, and a CIS film is deposited using spin-coating followed by annealing at 250 °C. The pasted carbon layer is utilized as the anode. No further sulfurization or selenization is employed. The Cu/In ratio in the ink is found as a critical factor affecting the morphology and crystallinity of the film as well as the photovoltaic performance of the device. An optimum Cu/In = 1.05 results in large-grain films with sharp diffraction peaks and, subsequently, optimal... 

    Preparation of a cuins2 nanoparticle ink and application in a selenization-free, solution-processed superstrate solar cell

    , Article European Journal of Inorganic Chemistry ; Volume 2015, Issue 35 , November , 2015 , Pages 5793–5800 ; 14341948 (ISSN) Cheshme Khavar, A. H ; Mahjoub, A. R ; Tajabadi, F ; Dehghani, M ; Taghavinia, N ; Sharif University of Technology
    Wiley-VCH Verlag  2015
    We report a study on chalcopyrite solar cells fabricated by low-cost, nonvacuum, and selenization-free methods. Superstrate-type CuInS2 (CIS) thin-film solar cells were prepared by sequential ink deposition. The CIS film was formed from a stable low-carbon ink, which was synthesized at low temperature (<120 °C). The CIS nanoparticle ink was prepared with n-butylamine and acetic acid as the solvent and stabilizer, respectively. The viscous and stable ink that formed through the dispersion of the final nanoparticles in N,N-dimethylformamide (DMF) could be deposited readily onto the substrate. The major features of the obtained ink are the small amount of impurity phases and negligible carbon... 

    Comparison of trap-state distribution and carrier transport in nanotubular and nanoparticulate TiO2 electrodes for dye-sensitized solar cells

    , Article ChemPhysChem ; Volume 11, Issue 10 , July , 2010 , Pages 2140-2145 ; 14394235 (ISSN) Mohammadpour, R ; Zad, A. I ; Hagfeldt, A ; Boschloo, G ; Sharif University of Technology
    Dye-sensitized solar cells (DSCs) with nanotubular TiO2 electrodes of varying thicknesses are compared to DSCs based on conventional nanoparticulate electrodes. Despite the higher degree of order in one-dimensional nanotubular electrodes, electron transport times and diffusion coefficients, determined under short-circuit conditions, are comparable to those of nanoparticulate electrodes. The quasi-Fermi level, however, is much lower in the nanotubes, suggesting a lower concentration of conduction band electrons. This provides evidence for a much higher diffusion coefficient for conduction band electrons in nanotubes than in nanoparticulate films. The electron lifetime and the diffusion length... 

    Highly efficient and stable perovskite solar cells based on a low-cost carbon cloth

    , Article Advanced Energy Materials ; Volume 6, Issue 20 , 2016 ; 16146832 (ISSN) Gholipour, S ; Correa Baena, J. P ; Domanski, K ; Matsui, T ; Steier, L ; Giordano, F ; Tajabadi, F ; Tress, W ; Saliba, M ; Abate, A ; Morteza Ali, A ; Taghavinia, N ; Grätzel, M ; Hagfeldt, A ; Sharif University of Technology
    Wiley-VCH Verlag  2016
    A low-cost carbon cloth is applied in perovskite solar cells (PSC) as a collector composite and degradation inhibitor. This study incorporates carbon fibers as a back contact in perovskite solar cells, which results in enhancement in all photovoltaic parameters. This material is suitable for large-scale fabrication of PSCs as it has shown an improved long-term stability when compared to the gold counterpart under elevated temperatures  

    A three-step method for the deposition of large cuboids of organic–inorganic perovskite and application in solar cells

    , Article ChemPhysChem ; 2016 , Pages 2389-2394 ; 14394235 (ISSN) Shahbazi, S ; Malekshahi Byranvand, M ; Tajabadi, F ; Afshar, Sh ; Taghavinia, N ; Sharif University of Technology
    Wiley-VCH Verlag 
    A three-step method for the deposition of CH3NH3PbI3 perovskite films with a high crystalline structure and large cuboid overlayer morphology is reported. The method includes PbI2 deposition, which is followed by dipping into a solution of C4H9NH3I (BAI) and (BA)2PbI4 perovskite formation. In the final step, the poorly thermodynamically stable (BA)2PbI4 phase converts into the more stable CH3NH3PbI3 perovskite by dipping into a solution of CH3NH3I. The final product is characterized by XRD, SEM, UV/Vis, and photoluminescence analysis methods. The experimental results indicate that the prepared perovskite has cuboids with high crystallinity and large sizes (up to 1 μm), as confirmed by XRD... 

    Simulation analysis of inverted organic solar cells with grating structure: undesirable effects of high absorption near grating anode

    , Article Optik ; Volume 154 , February , 2018 , Pages 453-458 ; 00304026 (ISSN) Bahrami, A ; Faez, R ; Sharif University of Technology
    Elsevier GmbH  2018
    An inverted organic solar cell (IOSC) with nanograting array as anode of the cell has been simulated and analyzed using a combined electrical and optical approach. We have used finite difference time domain (FDTD) method for optimizing device structure. We have compared the characteristics of the IOSC with grating structure with a reference IOSC without grating structure. As a result, an improvement of 11% and 26% in power conversion efficiency (PCE) and short circuit current (JSC) compared to the reference structure was achieved. An analysis is provided on the origin of reduced fill factor (FF) in the IOSC with grating structure. We also have discussed about disadvantage of using optical... 

    Effective management of nucleation and crystallization processes in perovskite formation via facile control of antisolvent temperature

    , Article ACS Applied Energy Materials ; Volume 3, Issue 2 , 2020 , Pages 1506-1514 Taherianfard, H ; Kim, G. W ; Malekshahi Byranvand, M ; Choi, K ; Kang, G ; Choi, H ; Tajabadi, F ; Taghavinia, N ; Park, T ; Sharif University of Technology
    American Chemical Society  2020
    The antisolvent method has been used extensively to induce the growth of high-quality perovskite layers for efficient solar cells. However, uncontrollable nucleation and crystallization increases the risk of formation of undesirable defects. Here, we report a facile way to control the nucleation and crystallization stages in perovskite formation by changing the temperature of chlorobenzene (CB) in the antisolvent method. When CB is injected on the spinning substrate with a precursor solution, CB temperature affects the nucleation process as well as the crystallization process. As the CB temperature increases, nuclei increase in size, leading to the formation of larger perovskite crystals... 

    Novel organic dyes with anchoring group of barbituric/thiobarbituric acid and their application in dye-sensitized solar cells

    , Article Synthetic Metals ; Volume 209 , November , 2015 , Pages 1-10 ; 03796779 (ISSN) Hosseinzadeh, B ; Salimi Beni, A ; Najafi Chermahini, A ; Ghahary, R ; Teimouri, A ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract New bi-anchoring donor-π-acceptor metal-free organic dyes based on diphenylamine as donor, and barbituric acid and thiobarbituric acid as the acceptor/anchor were synthesized, characterized and used in dye-sensitized solar cells applications. Among the fabricated dye sensitized solar cells, device based on the diphenylamine as donor, and barbituric acid as the acceptor exhibits a high power conversion efficiency of 1.53% with a short circuit current density of 3.71 mA cm-2, an open-circuit photo voltage of 0.55 V and a fill factor of 0.75% under AM 1.5 illumination (85 mW cm-2) compared to the other fabricated devices. The structure of synthesized dyes was optimized and their... 

    An easy method to modify PEDOT:PSS/perovskite interfaces for solar cells with efficiency exceeding 15%

    , Article RSC Advances ; Volume 6, Issue 70 , 2016 , Pages 65594-65599 ; 20462069 (ISSN) Shahbazi, S ; Tajabadi, F ; Shiu, H. S ; Sedighi, R ; Jokar, E ; Gholipour, S ; Taghavinia, N ; Afshar, S ; Diau, E. W. G ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Herein, we show that surface treatment of PEDOT:PSS films using propionic acid (PA) results in better device performance for the resulting CH3NH3PbI3 perovskite solar cells (PCE > 15%). N2 blow spreading of PA appears critical in enhanced performance. This weak acid treatment leads to no worse roughness, while providing larger perovskite grains  

    Self-assembled monolayer of wavelength-scale core-shell particles for low-loss plasmonic and broadband light trapping in solar cells

    , Article ACS Applied Materials and Interfaces ; Volume 8, Issue 1 , 2016 , Pages 247-255 ; 19448244 (ISSN) Dabirian, A ; Malekshahi Byranvand, M ; Naqavi, A ; Nemati Kharat, A ; Taghavinia, N ; Sharif University of Technology
    American Chemical Society 
    Scattering particles constitute a key light trapping solution for thin film photovoltaics where either the particles are embedded in the light absorbing layer or a thick layer of them is used as a reflector. Here we introduce a monolayer of wavelength-scale core-shell silica@Ag particles as a novel light trapping strategy for thin film photovoltaics. These particles show hybrid photonic-plasmonic resonance modes that scatter light strongly and with small parasitic absorption losses in Ag (<1.5%). In addition, their scattering efficiency does not vary significantly with the refractive index of the surrounding medium. A monolayer of these particles is applied as the top-scattering layers in a...