KEYWORDS: Thin films, Dye sensitized solar cells, Solar cells, Data modeling, Refractive index, Optical properties, Scanning electron microscopy, Thin film solar cells, Machine learning, Electrodes
Among various solar cell architectures, dye-sensitized solar cells (DSSCs) and perovskite solar cells have demonstrated the capability of being bifacial as both can be fabricated on conducting glass electrodes. In both cells, TiO2 plays a key role in the optoelectronic properties of the cell. Various studies have reported a range of recipes and deposition techniques for TiO2 thin films. Such variety introduces some uncertainties into the optical properties of the prepared films as well as in the process repeatability. Here, we utilized machine learning methods to correlate the film porosity to the film refractive index, making it capable of studying the impact of varying the fabrication and deposition techniques. Image postprocessing for scanning electron microscope measurements was utilized to estimate the film porosity, and the refractive index was calculated from the T–λ spectra. Four sets of samples with complete bifacial DSSCs were fabricated and characterized. They recorded a maximum current of 23.42 mA. They were fabricated using carboxymethyl cellulose-based suspension and deposited via the spin-coating sol-gel method. The fabricated cells showed an overall conversion efficiency of 7.9% under optical injection of the AM1.5G spectrum from the front side and LED indoor lighting from the counter electrode.
This paper proposes a new, robust and generic tool to investigate both the series and the shunt resistances, (parasitic resistances), as well as the ideality factor for new generations of solar cells. Focus is given to both dye-sensitized solar cells and perovskite solar cells, where the mesoporous TiO2 layer plays a significant role. A comprehensive study for the mesostructured-based solar cells with respect to conventional solar cells has been conducted regarding the parasitic resistance variation, the effect of the active material and technology on the ideality factor. Experimental data show acceptable agreement with data extracted from the proposed model where the targeted parameters have been estimated.
The aim of this paper is to study the behavior of the emission spectrum when there is a spectral interference or a spatial interference between the LEDs. Several heterojunction LEDs were desgined and modeled using COMSOL multiphysics. The simulated LEDs showed 3.75% average mismatch to the measured UV-Vis-NIR LEDs spectra. The heterojunction LED showed that the relative intensity has a direct proportional relation to the spectral interference and an inversely proportional relation to the spatial distribution. Moreover, the cool white LED was constructed using the royal blue LED and the yellow LED.
KEYWORDS: Earth Viewing Camera, Monte Carlo methods, Atmospheric modeling, Computer simulations, System on a chip, Renewable energy, Pollution, Stochastic processes, Roads
This paper presses a developed methodology of estimating the total number of charging points in the Electric Vehicle Charging Station (EVCS). Three various EVCSs in the urban core, suburban area and the rural area were modeled and investigated by using an established database for fourteen different Electric Vehicles (EVs) of different manufacturers. Monte-Carlo simulation technique (MCST) was applied with high-dense iterative runs to predict the peak hour energy demand that can be occurred in the proposed three zones besides expecting the arrival interval time of the EVs across the day according to the percentage of daily demand of each station. Moreover, an imperially constructed equation is used to calculate the number of charging points in each zone by estimating the normalized arrival time with the aid of MCST. The precise estimating of the total number of charging points for each station is minimizing the charging time and the queuing delay issues.
KEYWORDS: Photovoltaics, Solar cells, MATLAB, Solar energy, Telecommunications, Communication engineering, Systems modeling, Software development, Databases
System sizing is necessary for evaluating the PV system as first step before investing at a given project. However, there is a lack of developing MATLAB code for grid-connected system to present a techno-economic solution taking into consideration the less running time and covering our local needs. This paper aims to develop a pre-sizing offline tool using MATLAB software. Moreover, the developed code is integrated with tariffs and electricity bills for both low and medium voltages including all sectors. Furthermore, the tool is applied for all applicable areas like rooftop industrial shed and ground mounted. Hence, Egypt was applied in this tool through selecting four locations Cairo, Alexandria, Aswan and Hurghada. Case studies were sized using MATLAB code and validated by PVsyst, as result the percentage of error ranges from 1 to 6%. Additionally, developed code shows the capability of giving a full techno-economic solution in preliminary design stage. The results showed that Aswan was the best location for installing PV system technically and economically where the highest specific yield and capacity factor recorded were 2062 kWh/kWp/year, 24% respectively. Moreover, the lowest levelized cost of energy and simple payback period 0.56 EGP/kWh, 4.3 years respectively were recorder in Aswan.
Quantum key distribution introduces a new way of key exchange through a public quantum channel between two communicating nodes. However, the first introduced BB84 protocol was theoretically verifying security based on single photon sources. At this time, it was hard to achieve such device. Therefore, it was a challenging aspect to prove the security of QKD system using coherent light sources or “multi emitting photon source”, which introduces Photon number splitting attacks. We are interested to simulate and investigate the QKD system using coherent laser sources and study the PNS attack. The idea involves that; Eve can crash a beam of light, absorbing some photons using QND measurement and transmit the others. Such attack can make Eve dominant to the situation and gain much information of the key without the fear of getting exposed to the communicating parties. Herein, this paper discusses some useful solution to detect such attack and proves the security of QKD even with weak laser sources.
Solar simulators are built using various types of light sources having a spectrum similar to that of the sun. Some of these light sources include but are not limited to Xenon Arc Lamps, Metal Halide Arc Lamps and Quartz Tungsten Halogen Lamps. Since these lamps showed several disadvantages related to high cost, light stability, temporal stability and complexity, the usage of high-power LEDs was proposed as a simple and low-cost alternative. This solution boosted the popularity of solar simulators in the field of optical characterization. An array of LEDs is used to create a light source based on mixing different LED's colors with different spectrums, to produce a spectrum similar to that of the sun with a very low mismatch factor. In this paper we will introduce our implemented design with which we managed to reach a 12% mismatching factor at a distance 10 cm from the light source.
Porous TiO2 films are a crucial part of mesostructured solar cells (MSCs), both dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs). However, the literature does not provide a clear description of the optical properties especially of the refractive index and scattering for those films relevant to MSCs. In DSSCs, two different porous TiO2 layers are included, the mesoporous active layer and the blocking layer. While the first is essential for the charge separation, electron collection and ion conduction, the second is intended for suppressing the loss of generated electrons to the electrolyte. Both layers consist of the same chemical compound, TiO2, but they have different porosities. For PSCs, the perovskite is deposited on a mesoporous TiO2 structure for enhancing the I–V characteristics
This paper investigates TiO2 films really used in fabricated MSCs. We utilize a technique allowing the determination of the effective refractive index and the film porosity for two different film kinds fabricated using sol-gel methods, discussed in our previous work, to determine the thickness of TiO2 films typically used in fabricating MSCs.
Thin film solar cells (TFSCs) where first introduced as a low cost alternative to conventional thick ones. TFSCs show low conversion efficiencies due to the used poor quality materials having weak absorption capabilities and to thin absorption layers. In order to increase light absorption within the active layer, specially near its absorption edge, photon management techniques were proposed. These techniques could be implemented on the top of the active layer to enhance the absorption capabilities and/or to act as anti-reflecting coating structures. When used at the back side, their purpose is to prevent the unabsorbed photons from escaping through the back of the cell.
In this paper, we coupled the finite difference time-domain (FDTD) algorithm for simulating light interaction within the cell with the commercial simulator Comsol Multiphysics 4.3b for describing carrier transports. In order to model the dispersive and absorption properties of various used materials, their complex refractive indices were estimated using the Lorentzian-Drude (LD) coefficients. We have calculated the absorption profile in the different layers of the cell, the external quantum efficiency and the power conversion efficiency achieved by adding dielectric nanospheres on the top of the active layer. Besides that, the enhancement observed after the addition of dielectric nanospheres at the back side of the active layer was computed. The obtained results are finally compared with the effects of using textured surface and nanowires on the top in plus of cascaded 1D and 2D photonic crystals on the back.
A comparison between Silicon (Si) which is an indirect band-gap semiconductor and Gallium Arsenide (GaAs) as a
direct band-gap semiconductor for vertical-aligned nanowire radial pn junction-based photovoltaic (PV) devices is
presented. The study takes place through determining the fill factor, the power conversion efficiency, the optimum
device length and the spectrum of the quantum efficiency. The sensitivity of both Si and GaAs nanowire to temperature
variations is also investigated. Finally, the array effect for nanowires of each material alone then of arrays of mixed
elements' types is simulated. The results are found to be in accordance with the available experimental measurements.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.