Güneş pili uygulamaları için tek duvarlı karbon nanotüpler tabanlı meta malzeme soğurucusu

Carbon nanotubes possess superior mechanical and electrical properties such as being lightweight, strong, and flexible; and having high electrical conductivity. Solar cells containing single-walled carbon nanotubes that absorb photons near infrared region have been a focal area of research and development due to their promising characteristics of harvesting light in the long wavelength region, cost effectiveness and performance. Absorption properties of SWNTs are not yet well studied quantitatively, even though their importance is very significant for the new solar technologies. In this thesis, various SWNT based metamaterial absorbers with almost 99% absorption capability have been designed and numerically simulated for the solar cell application. The compact structure and maximum absorption of MTM absorber can provide highly efficient and cost effective solar cell. Novel wide-band, triple-band, and multi-band polarization-insensitive metamaterial absorber structure with semiconducting SWNT as the dielectric layer is proposed to efficiently absorb the incident electromagnetic radiations in a wide-range frequency region. Computed results are verified analytically by interface theory and also with the previously reported MTM absorbers available in the literature as well as with different solver techniques such as FEM and FIT.Karbon nanotüpler (KNT) hafiflik, sertlik, esneklik, ve yüksek elektriksel iletkenlik gibi üstün mekanik ve elektriksel özelliklere sahiptirler. Tek Duvarlı Karbon Nanotüpler (TDKNT) içeren ve kızılaltı bölgesi civarındaki fotonları emen güneş pilleri uzun dalga boyu bölgesindeki ışımadan faydalanma, ucuz ve yüksek performanslı olma gibi özelliklerinden dolayı popüler bir araştırma ve geliştirme alanıdır. TDKNTler yeni güneş pili teknolojileri için önem arz etmekle beraber soğurma özellikleri nicel olarak yeterince araştırılmamıştır. Bu tezde, güneş pili uygulamaları için %99 soğurma kapasiteli, TDKNT tabanlı çeşitli meta malzeme soğurucular tasarlanmış ve bu soğurucuların numerik olarak simülasyonu gerçekleştirilmiştir. MTM soğurucularının kompakt yapısı ve maksimum soğurma oranları, oldukça yüksek verimli ve uygun maliyetli güneş pillerinin gerçekleşmesini sağlayabilir. Yeni geliştirilmiş geniş-bantlı, üç-bantlı ve çok-bantlı kutuplaşmadan bağımsız, yalıtkan katman olarak yarı iletken TDKNT içeren meta malzeme soğurucular, gelen elektromanyetik radyasyonunu geniş bir frekans aralığında verimli bir şekilde soğurmak için önerilmiştir. Hesaplanmış sonuçlar analitik olarak girişim teorisi ile doğrulanmıştır. Ayrıca literatürde daha önceden yayınlanan MTM soğurucular larla da FEM ve FIT gibi çeşitli çözüm teknikleri kullanılarak doğrulama yapılmıştır.M.S. - Master of Scienc

Improvement in dye sensitized solar cells from past to present

Several emerging renewable technologies are available to satisfy the current energy demand and to minimize the effect of environmental degradation caused by high consumption of fossil fuels. These technologies are not mature enough to solve this problem but require more time for improving the efficiency, and cost reduction to become the economical alternative of fossil fuels. In this paper Dye-sensitized solar cell (DSSC) has been discussed in detail owing to advancement in the technology. Since each component of DSSC is responsible for a specific function, therefore, comprehensive literature studies has been done on individual section to understand the technology in depth. All the advancement in sensitizer, semiconductors, electrolyte, electrodes, additives, sealing and anchoring groups are included in this review with performance parameter of DSSC. Focus of this article is to provide summary of all available literature since beginning to date

The relationship between carbon dioxide emissions, energy consumption, and GDP: A recent evidence from Pakistan

In this study an attempt was made to investigate carbon dioxide emissions, energy consumption (EC), GDP, and electricity production from oil, coal and natural gas, a recent evidence from Pakistan by employing a time series data spanning from 1971 to 2013. The study employed the vector error correction model to estimate the long-run equilibrium relationship. There was evidence of long-run equilibrium relationship running from EC, electricity production from coal, electricity production from natural gas, electricity production from oil and GDP to carbon dioxide emissions. The policy implication of the VEC model means that a 1% increase in energy production from oil in Pakistan will increase carbon dioxide emissions by 13.7% in the long-run. There was evidence of a unidirectional causality running from EC to carbon dioxide emissions, electricity production from natural gas to EC, EC to electricity production from oil, electricity production from natural gas to GDP and GDP to electricity production from oil. Evidence from the generalized impulse-response analysis shows that three components contribute to carbon dioxide emissions in Pakistan, which include EC, energy production from gas and GDP

Single- and multi-walled carbon nanotubes for solar cell applications

Emerging nanotechnologies have revealed carbon nanotubes (CNTs) as one of the best materials with immense potential. Considering the outstanding physical, mechanical, electrochemical, thermal, and optoelectronic properties of CNTs, extensive studies have been reported assessing their applications in several disciplines. This paper presents a broad review of the studies in the literature that address the contribution of CNTs in terms of their applications as different parts of solar cells such as photoelectrode, photoconductor, top and back electrode, replacement of indium tin oxide (ITO) as transparent conducting electrode (TCE) in a variety of photovoltaics such as silicon, organic, polymer and dye-sensitized with their subsequent efficiencies

Thin film (6,5) semiconducting single-walled carbon nanotube metamaterial absorber for photovoltaic applications

A wide-band (6,5) single-walled carbon nanotube metamaterial absorber design with near unity absorption in the visible and ultraviolet frequency regions for solar cell applications is proposed. The frequency response of the proposed design provides wide-band with a maximum of 99.2% absorption. The proposed design is also simulated with (5,4), (6,4), (7,5), (9,4), and (10,3) chiralities, and results are compared to show that the proposed design works best with (6,5) carbon nanotube (CNT) but also good for other chiral CNTs in the visible and ultraviolet frequency region. The geometric structure was carefully analyzed for its contribution to the absorption behavior. The absorber design is highly flexible and capable of keeping the wide-band with high absorption. Due to the excellent symmetric characteristics of the proposed design, which provides polarization independency under normal incidence (transverse electromagnetic mode), the proposed metamaterial absorber is a good candidate for the solar cell application, where absorbance can be kept high with respect to the polarization angle. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE

Polarization independent triple-band (5,4) semiconducting carbon nanotube metamaterial absorber design for visible and ultraviolet regions

Various metamaterial absorber designs operating in the microwave, infrared, visible, and ultraviolet frequency regions have been proposed in the literature. However, only a few studies have been done on the metamaterials that absorb in both visible and ultraviolet solar spectra. A triple-band polarization-insensitive metamaterial absorber structure with semiconducting single-walled carbon nanotube as the dielectric layer is proposed to efficiently absorb the incident electromagnetic radiations in visible and ultraviolet frequency regions. A unit cell of this design comprises three basic components in the form of metal-semiconductor-metal layers. The metallic part of the structure is aluminum, and the (5,4) single-walled carbon nanotube is used as the semiconducting material. The electromagnetic response of the proposed design is numerically simulated in the visible and ultraviolet regions with the maximum absorption rates of 99.75% at 479.4 THz, 99.94% at 766.9 THz, and 97.33% at 938.8 THz with corresponding skin depths of 13.0, 12.8, and 12.9 nm, respectively. Thus, solar cells based on this metamaterial absorber can offer nearly perfect absorption in the suggested frequency regions. The simple configuration of the design provides flexibility to control geometric parameters to be used in the solar cell and possesses the capability to be rescaled for other solar spectrum. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE

Electricity production potential and social benefits from rice husk, a case study in Pakistan

Pakistan has been experiencing energy crisis owing to its sole dependence on fossil fuels. Reduction in local fossil fuel reserves has led to an increase in their prices, thereby increasing the cost of electricity. Since the tariff remains the same, Pakistan is over-burdened with circular debts and observes a daily power shortfall of about 12–14 h. Being an Agra-economic country, many major and minor crops are produced and exported in large quantities. This results in a bulk of the agricultural waste which are not utilized. The waste can be utilized to meet the country’s energy demand while mitigating climate change and its impact. The study examines the electricity production potential and social benefits of rice husk in Pakistan. It is estimated in this study that if 70% of rice husk residues are utilized, there will be annual electricity production of 1,328 GWh and the cost of per unit electricity by rice husk is found at 47.36 cents/kWh as compared to 55.22 cents/kWh of electricity generated by coal. Importantly, the study will increase the awareness of the benefits of utilizing agricultural waste for useful products such as silica, with several social and environmental benefits such as a reduction of 36,042 tCO_2e/yr of methane, reducing carbon dioxide emissions, improving the air quality, and providing 4.5 k new jobs. The paper concludes with the policy recommendations based on this study

Investigating the impact of different sport trainings on particulate matter resuspension in a sport center using well-characterized reference instruments and a low-cost monitor

Abstract The present study investigated the exposure of teenagers, adults, and students to PM1, PM2.5, PM4, PM10, particle number concentration at two sport facilities of Nazarbayev University including Gymnastics Hall and Multi-purpose Hall. Measurements were conducted during variety of sport training sessions including soccer, basketball, volleyball, Mixed Martial Arts (MMA), boxing, table tennis, etc. A low-cost instrument, Dylos was employed to compare its performance against two TSI instruments. In overall, the Dylos showed acceptable peaks when the source of particle resuspension was present. However, no correlation was observed between Dylos data and Dusttrak fine and coarse particle data. The average PM2,5 and PM10 concentrations were found to be below the WHO limits. The number of participants during the training sessions and sports involving balls including basketball, soccer and volleyball were the two factors responsible for the observed increased particle resuspension