Sharif Digital Repository

Preparing a selective, efficient, and low-cost solar absorber is one of the main challenges in solar to thermal energy conversion. In this paper, black electroless Ni–P (ENi-P) solar absorber has been fabricated, and the effect of nanoporous TiO2 antireflection layer (ARL) on its optical and corrosion properties has been investigated. The optimum black coating was obtained by blackening in 9 M nitric acid solution at 50 °C for 40 s, in which a solar absorptance of 99.3% was achieved. Deposition of TiO2 ARL increased the solar absorptance of coating to 99.7% and addition of 0.8 g Pluronic F127 (F127) as pore former, further increased this value to 99.9% and solar-to-heat efficiency of the... 

The effect of the corona wind on the natural convection at absorber of a solar chimney power plant pilot was investigated experimentally. The aim of the study is to improve the efficiency of SCPP through enhanced the heat transfer coefficient of absorber with corona wind. The results show that corona wind enhanced the absorber convective heat transfer coefficient leading to increment in air the velocity and the output power of the SCPP. The amount of heat transfer of pilot increased more than 14.5% when applying voltage of 15 KV and the speed in chimney experienced about 72% amelioration  

In this paper by solving Dirac equation, we present an analytical solution to calculate energy levels and wave functions of mono- and bilayer graphene quantum dots. By supposing circular quantum dots, we solve Dirac equation and obtain energy levels and band gap with relations in a new closed and practical form. The energy levels are correlated with a radial quantum number and radius of quantum dots. In addition to monolayer quantum dots, AA- and AB-stacked bilayer quantum dots are investigated and their energy levels and band gap are calculated as well. Also, we analyze the influence of the quantum dots size on their energy spectrum. It can be observed that the band gap decreases as quantum... 

Interface engineering of solar cell device is a prominent strategy to improve the device performance. Herein, we synthesize reduced-graphene scaffold (rGS) by using a new and simple chemical approach. In this regard, we synthesize a hollow structure of graphene and then fabricate a three-dimensional scaffold of graphene with a superior surface area using electrophoretic process. We employ this scaffold as an interface layer between the electron transfer and absorber layers in perovskite solar cell. The characterization tests and photovoltaic results show that rGS improves the carrier transportation, yielding a 27% improvement in device performance as compared to conventional device. Finally,... 

Due to significant reduction in fossil fuel sources, several researches have been conducted recently to explore modern sources of renewable energy. One of the major fields in the category of renewable energy harnessing devices is parabolic trough solar collector (PTC). Several parameters have effect on the overall efficiency of the PTCs. As the effect of these parameters is coupled to each other, a comprehensive investigation is necessary. In the present study, a numerical analysis is performed to examine the efficiency of PTCs via variation of several governing parameters (e.g., wind velocity magnitude, nanoparticles volume fraction, inlet temperature, and reflector's orientation). A... 

Today manufacturing of high efficiency chalcogenide thin film solar cells is based on high cost vacuum-based deposition processes at high temperature (>500 °C) and in chalcogen -containing atmosphere. In this paper, we introduce a simple vacuum-free and selenization-free, solution processing for fabricating a superstrate-type CuInS2 (CIS) solar cell. The absorber, buffer and blocking layers were all deposited by spin coating of molecular precursor inks. We demonstrate the deposition of In2S3 buffer layer by sol-gel spin casting for the first time. The rapid sintering process of CIS layer was carried out at 250 °C that is considered a very low temperature in CIGS thin-film technologies. A... 

A modeling approach is presented for the first time to model the dependence of short-circuit current density (J sc ) and open-circuit voltage (V oc ) on the grain size g in three thin film solar cells including the emerging perovskites. The variation of J sc and V oc with the grain size (g) of three different solar cells with CdTe, CZTS and perovskite absorber layers are modelled and fitted with the experimental dataset collected from relevant literature. The experimental literature suggested that the grain size of absorber layers in solar cells is controlled during the deposition process by adjusting the growth rate, temperature and ambient. The model has been successfully applied to the... 

Studies on copper zinc tin sulpher selenide (CZTSSe) thin-film material and its applications as a base material are intensively being researched since it is an earth-abundant, inexpensive, flexible, and interesting material for next-generation optoelectronic technologies. Apropos, this study explores and reports the synthesis of CZTSSe thin films and their key optoelectronics characteristics. The reported films are fabricated on a soda-lime glass substrate by using a physical vapor deposition technique, and then annealed from 250 to 450 °C. From the X-ray diffraction analysis, the structure of the as-deposited thin films is found to be amorphous in nature. Annealed thin films of CZTSSe... 

Studies on copper zinc tin sulpher selenide (CZTSSe) thin-film material and its applications as a base material are intensively being researched since it is an earth-abundant, inexpensive, flexible, and interesting material for next-generation optoelectronic technologies. Apropos, this study explores and reports the synthesis of CZTSSe thin films and their key optoelectronics characteristics. The reported films are fabricated on a soda-lime glass substrate by using a physical vapor deposition technique, and then annealed from 250 to 450 °C. From the X-ray diffraction analysis, the structure of the as-deposited thin films is found to be amorphous in nature. Annealed thin films of CZTSSe... 

During the last decades, the adoption of more strict safety and environmental regulations, as well as a rise in energy costs, sparked an increasing interest in the design of renewable energies systems, particularly solar systems, to supply both electrical power and heat. Because of their capability to simultaneously supply both electricity and heat, concentrating photovoltaic-thermal and thermoelectric hybrid systems have recently attracted scholarly attention. In this study, a detailed three-dimensional computational model of a novel concentrating photovoltaic-thermal solar system combined with thermoelectric modules in an integrated design with a triangular absorber and corresponding...