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Solar cells made of Cadmium telluride (CdTe), copper indium gallium selenide (CIGS) and copper zinc tin sulfide (CZTS) are currently the most widely studied thin film technologies.To increase the performance and for better understanding of the behavior of CdTe, CIGS and CZTS solar cell simulations have been performed using WxAMPS software. Moreover, all the solar cells have been simulated with different buffer layers and transparent conductive oxide (TCO) layers such as Cadmium Sulphide (CdS), Zinc Sulphide (ZnS), Aluminum Zinc Oxide (AZO) and Indium Tin Oxide (ITO).Variations in the thickness and doping concentrations of TCO layers, buffer layers, and absorber layers have been done to test the performance of the solar cells.The effects of using a Back-Surface Reflector (BSR) layer made of Zinc Telluride (ZnTe) have also been studied.Furthermore, the simulation work is exceptional in this regard since all of the layers of CdTe, CIGS, and CZTS solar cells were modeled using optical parameters (absorption coefficients) from the literature. All the solar cell's open circuit voltage (Voc), short circuit current (Isc), maximum power (Pm), fill factor (FF), and photovoltaic efficiencies have been represented in this work. The simulation results may provide valuable insight in developing and better understanding of high-efficiency thin film solar cells.

In this work, the impact of six different anti-reflection coating (ARC) layers has been investigated using PC1D simulation software. Simulation shows that the range of 500–700 nm would be suitable for designing an ARC. Designing a single-layer silicon nitride (Si3N4) ARC for 600 nm wavelength and with a thickness of 74.257 nm, a silicon solar cell with 20.35% efficiency has been simulated. Very closely followed by a 20.34% efficient silicon solar cell with 74.87 nm thick zinc oxide (ZnO) ARC layer. Significant increase in efficiency has been observed by applying ARC in respect to not applying any kind of ARC. After efficient solar cell modeling, optimum efficiency of 20.67% is being achieved by using SiO2 surface passivation and Si3N4 ARC layer. The effects on voltage, current, photovoltaic efficiency, reflectivity and external quantum efficiency due to ARCs are also represented in this work.

Band gap of P-type monocrystalline silicon wafer has been measured using spectral response measurement system. To see the spectral response a SR510 lock in amplifier, SR540 optical chopper, monochromator (400nm-1200nm), optical detector and lab view software has been used. From spectral response of polished P-type monocrystalline silicon wafer absorption, reflection and transmission has been respectively seen from 400nm-550nm, 550nm-1050nm and 1050-1200nm. Assuming band gap of silicon is (1.12eV), this result has been theoretically verified using Planck–Einstein relation. Moreover, theoretical band gap of silicon has been calculated (1.127362 eV). The band gap measurement process uses partial concept of Tauc’s downhill negative slop and Planck–Einstein relation. Experimental result shows that, the band gap of silicon is 1.127907 eV.Bangladesh J. Sci. Ind. Res.53(3), 179-184, 2018

Implementing texturization process on the monocrystalline silicon substrate reduces reflection and enhances light absorption of the substrate. Thus texturization is one of the key elements to increase the efficiency of solar cell. Considering as-cut monocrystalline silicon wafer as base substrate, in this work different concentrations of Na2CO3 and NaHCO3 solution, KOH–IPA (isopropyl alcohol) solution and tetramethylammonium hydroxide solution with different time intervals have been investigated for texturization process. Furthermore, saw damage removal process was conducted with 10% NaOH solution, 20 wt% KOH–13.33 wt% IPA solution and HF/nitric/acetic acid solution. The surface morphology of saw damage, saw damage removed surface and textured wafer were observed using optical microscope and field emission scanning electron microscopy. Texturization causes pyramidal micro structures on the surface of (100) oriented monocrystalline silicon wafer. The height of the pyramid on the silicon surface varies from 1.5 to 3.2 µm and the inclined planes of the pyramids are acute angle. Contact angle value indicates that the textured wafer’s surface fall in between near-hydrophobic to hydrophobic range. With respect to base material absolute reflectance 1.049–0.75% within 250–800 nm wavelength region, 0.1–0.026% has been achieved within the same wavelength region when textured with 0.76 wt% KOH–4 wt% IPA solution for 20 min. Furthermore, an alternative route of using 1 wt% Na2CO3–0.2 wt% NaHCO3 solution for 50 min has been exploited in the texturization process.

Cancer, one of the leading causes that bring confirm death, is the subject of widespread fear and taboos. Although the complete elimination of cancer hasn't been discovered yet, "the war against cancer" has already been declared worldwide and research works are ongoing for cancer medicines. This paper presents a review on "Gold Nano Particle (GNP)", a magic bullet which might be the timely solution to bring win against cancer malignancy. GNPs can be used as cancer drug carriers, contrast agent or in target cancer therapy etc. Because cancer cell membrane has Nano size holes, the Nano structure of GNP would help it to enter the cancer cells. It has also the dissolving abilities, so no harm would be done to other parts of the body. By using near infrared LASER, localized heating of GNPs is also possible to destroy cancer cells. Test on rats using GNPs is found successful and the implementation on human is a matter of time. In Vitro and In Vivo observations on GNPs show much promises in near future. In 2013, WHO launched the Global Action Plan for the Prevention and Control of cancer (2), but still there has been no confirm solution how cancer can be cured. The National Cancer Institute (NCI) of US believes that nanotechnology could be the solution to cancer and has launched a plan of actions for achieving this great goal of harnessing power of nanotechnology to create a way to diagnose cancer and to locate and destroy these cancerous cells in the person's body with the help of nanotechnology (3). Various nonorganic nanoparticles like Gold Nanoparticles (GNPs), SPIONs (Super Paramagnetic Iron Oxide Nanoparticles) and quantum dots (QDs) could be used as cancer Nano medicine. Of all nanoparticles, GNP hints the most promising future to cure cancer diseases because of its dissolve properties, small size, non-toxicity etc. Special magnetic characteristics are also found in GNPs which can be used to increase heat by MRI or X-Ray machine; those increased heat can be tooled to destroy cancer cells. In Vitro and In Vivo observations on GNPs are ongoing and significant result has been found. This paper reviews these special applications of GNPs in cancer treatments to have a clear insight of the futures of nanoparticle in medical treatment.