Sharif Digital Repository

In the last years, perovskite QDs have emerged as the novel candidate due to their unique optical properties such as high-absorption coefficient, long-range charge transport, low exciton-binding energy, and etc. Nonetheless, poor stability of perovskite in ambient conditions made researchers to consider this issue. Recently, amoung various types of organic-inorganic perovskites, Formamidinium lead iodide has attracted tremendous attention due to its near IR absorption wavelength in addition to the higher stability compared to MAPbI3. In this work, FAPbI3 perovskite stability improvement was investigated by several methods under different conditions. In the first step, FAPbI3 QDs colloidal... 

Nowadays, dye-sensitized solar cells (DSSCs) are highly regarded as a cheap alternative for conventional silicon-based solar cells. Improvements of their efficiency and performance sustainability are two major challenges of their commercialization. Engineering of the photoanode electrode by controlling its thickness, chemical composition, and morphology was proposed as effective method in increasing the light conversion efficiency of the cells. In the present study, mesoporous TiO2 beads with different arrangements including pristine mesoporous beads, mixtures of mesoporous beads with nanoparticles, and in the form of two-layer structure of nanoparticles (as an active layer) and mesoporous... 

In this research, we fabricated and characterized hybrid organic-inorganic perovskite solar. The purpose of this study was the fabrication of multi-cationic perovskite films with vapor-assisted solution process, which was carried out in two different atmospheric and low-pressure conditions. In this regard, the reference cells with CH3NH3PbI3 and HC(NH2)2PbI3 compositions were made, which yielded 15.2% and 7.19% efficiencies in atmospheric conditions, and 6.38% and 2.65% in low pressure conditions, respectively. To increase the stability and to improve cell device performance, Br anion was added to the CH3NH3PbI3 structure. In optimum conditions, the conversion efficiency was 12.18%. Further... 

Today organometallic perovskites are very important in fabrication of solar cells. This materials have advantages like high mobility of charge carriers, changing in range of light aborption with changing in structures atoms, having longer charge carrier diffusion lengths than other materials, high stability and efficiency, Low-cost fabrication process, having capability of studying and processing in low temperatures and having flexibility because of Weak chemical bond in perovskite structure. Due to the low stability and rapid decomposition of this material with the presence of light and moisture, in this study has tried to use PbS quantum dots which is used in sensitive dye solar cells as... 

Organometal lead halides due to their interesting optical properties and convenient synthesis processing have attracted many attention recently. In this project, fabrication of lead halide perovskite solar cells through one-step deposition and two-step deposition with different holding time of PbI2 layers in various concentration of CH3NH3I solution as a second precursor within the ambient and glove box atmosphere has been studied. Structural, microscopic and photovoltaic properties of fabricated solar cells were evaluated. Moreover effect of delay time during PbI2 deposition on TiO2 mesoporous layer in performance of perovskite solar cell using Energy Dispersive Spectroscopy was studied.... 

The microstructure, morphology and quality of the perovskite organic-inorganic layer as an absorber layer in perovskite solar cells has a significant role on the efficiency and energy conversion of the device. Different solvent engineering methods have been employed to prepare the perovskite layer with the desired properties and thier reproducibility have been studied. Herein, we applied a two-step solution approach by solvent engineering method, using solvents such as isopropyl alcohol, acetone and thier mixture, for preparation of lead iodide films. Moreover, their metallurgical and photovoltaic properties were investigated. The impact of solvent engineering, using solvents such as... 

In this research, we focus on study and fabrication of organic inorganic solar cells. We use and optimize various methods such as one-step spin-coating, two-step sequential deposition and vapor-assisted solution process (VASP), to prepare high quality perovskite films. One-step deposition is simplest method for deposition of perovskite films. Although perovskite deposition by this method is very simple, the control of uniformity and surface film morphology is difficult. Chlorine inclusion, optimization of annealing conditions, and a sequential solution-based deposition method have been demonstrated to increase film coverage and uniformity. Hence, we use sequential deposition method for... 

Finding a reliable and reproducible method to deposit thin films of semiconductors is a huge leap forward in order to fabricate nano-structured solar cells. As the third and forth generation of solar cells are based on semiconductors which are soluble in solvents and can be deposited with solution-based methods, finding a proper printing mechanics can lead to cheap solar panels. In this thesis we have designed and fabricated an apparatus to deposit lead iodide films. These thin films can be used to fabricate perovskite solar cells which are based on methylammonium lead iodide perovskite. We have also investigated different inks consisting of different additives and solvents best suited for... 

Morphology, microstructure, phase composition and arrangement modes of the photoanode electrode are the most important parameters which affect the photovoltaic properties of dye-sentisized solar cells (DSSCs). In most DSSCs the scattering layer has been used to improve their efficiency. In addition, there are different techniques to improve the electron transport using different morphologies of titania such as one-dimensional nanostructures. In this research, the effect of peroskite structures on electron transport and scattering effect is investigated. Using sol-gel process, the compositions will be produced which have special morphology and appropriate band gap in spite of pure titania.... 

The highest efficiency of Perovskite solar cells that is attained up to now, is around 24%. This champion solar cell is prepared under vacuum. This method suffers from low rapidity, small deposition area and high cost which are not compatible with commercialization. Printing method has a special position in mass production of electronic equipment, such as solar cells. This method has the potential of high rapid, low cast and repeatable deposition. In this thesis, I introduce a novel deposition method, named Capillary Adhesion Coating, which is based on capillary concept. The novel deposition method coats infinite perfect thinfilms with high rapidity and low cost. After the introducing of... 

Perovskite solar cells, with high efficiency operation, have been candidated as a cost-effective and environmentally friendly technology. Despite the great progress, there are some primarily issues remained regarding to the perovskite film and its fabrication methods. A very common perovskite cell structure is FTO/TiO2/CH3NH3PbI3/Spiro-OMeTAD/Au. Although, this structure has some advantages, lack of full surface coverage of perovskite film leads researchers to put much effort on finding other constructions. This surface inhomogeneity reduces the amount of light absorption and therefore efficiency. One way to produce a complete and uniform film is applying mixed-halide composition; such as... 

Increase in growing concerns over environmental pollution and depletion of fossil fuel resources motivate the need for cleaner energy technologies and stimulate research in facilitating renewable energy systems. In recent years, photovoltaic systems have attracted great attention since they remove the need for energy storage systems and intermediate processess for energy conversion. However, high capital cost, low efficiency and low energy density per area of these systems, as compared with other technologies hinder its industrial use. To surmount these bottlenecks and improve technical performance of PV systems, it is crucial to optimize configuration of convertor connection and to improve... 

The purpose of this study is fabrication and characterization of a mesoporous Perovskite solar cell using Barium Titanate as the mesoporous electron transfer layer. In this study, TiO2 nanoparticles and BaTiO3 oxide perovskites were prepared by sol-gel synthesis method and their pastes were applied to the conductive substrate by spin coating method and applied to electron transfer layer in perovskite solar cells. Then Perovskite solar cells were fabricated with different structures from the electron transfer layer.The results of X-ray diffraction analysis showed that pure Barium Titanate and Titanium dioxide nanoparticles were successfully synthesized with tetragonal and cubic crystal... 

Dye-Sensitized solar cells are the third generation of solar cells that have the potential to increase efficiency as much as solar cells of previous generations, along with lower prices. The cathode electrode of the pigmented solar cell as one of the essential components of the cell plays the role of accelerating the oxidation reaction reduction of the electrolyte. Platinum often is used as a catalyst layer. To reduce production costs and maintain cell viability, platinum should replace with other materials at a lower cost and higher electrochemical activity. Recently, carbon materials have been considered for the production of inexpensive solar cells with suitable performance. Among... 

This study presents a facile sol-gel template-assisted route to prepare CNT-TiO2 hybrid structures (CTH) for dye-sensitized solar cell (DSSC) applications. Non-covalent functionalized multi-walled carbon nanotubes (CNTs) with average diameter of 80 nm are used as the template for TiO2 deposition. The X-ray diffraction reveals that the hybrid structures are composed of primary anatase TiO2 nanoparticles with the average crystallite size of 12 nm, after heat treatment at 450°C in air atmosphere. TEM and FESEM images show that the shell thickness of the coated TiO2 on CNTs’ outmost walls varies between 60 to 120 nm, when the ratio of CNTs:TiO2 is 10wt. %. Photovoltaic measurements demonstrate... 

In the present work, we have designed a novel CdS/CdTe solar cell based on CdS nanowires, as a window layer, and CdTe nanoparticles, as a absorber layer. CdS nanowires and CdTe nanoparticles were synthesized by solvothermal method. The samples were characterized by X-ray diffraction diffractometer (XRD), field emission scanning electron microscope (FE-SEM), Atomic Force Microscope (AFM) and Ultraviolet–Visible (UV–vis) spectroscopy spectrometer. Photocurrent measurements were carried out using a 150 W xenon lamp with an air-mass (AM) 1.5 filter. The performance of the solar cell based on the CdS nanowire (NW-CdS) film with 225 nm thickness and CdTe nanoparticle (NP-CdTe) film with 6 μm... 

Titanium dioxide (TiO2) is a transparent n-type semiconductor with wide band gap which makes it suitable for applications such as solar cells. TiO2 dye-sensitized solar cells (DSSCs) transform the visible light energy to the electrical energy by excitation of absorbed dye. In the present study, TiO2 nanowires and nanoparticles were synthesized by hydrothermal and sol-gel methods, respectively. The effect of TiO2 morphology on photovoltaic performance of the cells was studied by fabrication of single layer DSSCs containing pure nanowires, pure nanoparticles and mixture of nanowires and nanoparticles with various weight ratios. The results revealed that, DSSC made of 10 wt% nanowires and 90... 

According to Iran's proper location to take advantage of solar energy and the ability of nanostructured solar cells fabrication in the country, in this study, the manufacturing problems and complexities of nanostructured solar cells such as dye solar cells and perovskite-based solar cells are investigated. The chromium metal as an alternative to the transparent conductive substrates in order to reduce the manufacturing cost of dye solar cells (DSCs) and reducing series resistance is introduced in this study. In case of utilizing chromium as a substrate for photoanode, the thickness of CrxOy layer is controlled by depositing TiO2 compact layer and the efficiency of DSC is increased from 2.6%... 

The Cu2ZnSnS(e)4 (CZTS(e)) quaternary and Cu2SnS3 (CTS) ternary componds with suitable optical and electrical properties have been considered as an emerging semiconductors for fabrication of thin-fim solar cells. So far, two technologies based on CdTe and CuInGaS(e)2 absorbers have achived efficiencies above 20%. However, these compounds contain toxic element Cd and rare elements such as In and Ga which, limited the development of these solar cells.In this research a 3-stage method was used for fabrication of CZTS(e) thin Films. In the first stage, CTS layers were deposited by spray pyrolysis method, in the second one, ZnS layers were also deposited on CTS layers by spray pyrolysis method... 

Last generation of solar cells which are organo-metal halide perovskite solar cells (PSCs) with power conversion efficiency over 20% are increasingly comparable to the silicon types, these PSCs are poorly stable under working environment. Carbon-based PSCs with lower cost and more stability seem a better choice for commercialization in future. In these PSCs TiO2 and NiO are working as electron and hole transporting materials, respectively. In addition, ZrO2 film between two mentioned layers works as a buffer layer to prevent direct contact. In this thesis, the initial powder, necessary for fabricating the buffer layer is synthesized at the first place. Then, since the printing method is a...