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In recent years, the photovoltaic community has been paying much interest to solar cells with dopant-free carrier selective contacts. In such solar cells, the collection of carriers is achieved by introducing a band offset due to the asymmetry in band alignment with silicon. These dopant-free carrier selective contacts can be deposited on c-Si through simple, low-temperature techniques such as evaporation, spin coating, spray pyrolysis, etc. This work demonstrates the carrier selective potential of MoOx and MgOx films by fabricating Au/MoOx/n-Si/Ag and Al/MgOx/p-Si/Au heterojunction diodes, respectively. Both heterojunction structures showed good diode behavior in the dark. Then we fabricated a double heterojunction carrier selective solar cell with MoOx (where x is slightly less than 3) as the hole-selective layer (HSL) and MgOx/Al stack (where x is slightly less than 1) as the electron-selective layer (ESL) on the front and rear side of a planar n-type c-silicon substrate. The thermal evaporation technique was chosen for the deposition of MoOx and MgOx, as a low-cost fabrication method for the crystalline silicon solar cell. ITO was used as the transparent front contact, over which the Ag grid was deposited. The performance of the fabricated Ag/ITO/MoOx/n-Si/MgOx/Al double heterojunction solar cell was analyzed. A power conversion efficiency of 3.73 % was obtained with a short-circuit current density of 20 mA/cm2 and an open-circuit voltage of 410 mV. [ABSTRACT FROM AUTHOR]

Design of multilayer anti-reflection coating (ARC) to reduce reflection losses from the surface of crystalline silicon solar cells requires materials having a wide range of refractive indices. In this paper, we use a series of low temperature (200°C) processed silicon-rich silicon nitrides and oxynitrides having optically engineered refractive indices for fabricating bi, tri and Rugate ARCs. We demonstrate that these multi-layer systems not only reduce the reflection losses for improved current collection but also have superior passivation properties to increase open-circuit voltage in silicon solar cells. The tri-layer ARC reduces the weighted average reflectance by 4.5% as compared to single ARC along with a minority carrier lifetime of 425 µs and implied voltage of 657mV making it a promising candidate as ARC for silicon solar cells. [ABSTRACT FROM AUTHOR]

Colorimetric sensors are extensively explored class of optical biosensors due to the visible eye detection enabled by them. An efficient way of colorimetric sensing can be achieved by studying the surface plasmon resonance (SPR) properties of noble metal nanoparticles like gold, silver etc. The SPR band of gold nanoparticles is influenced not only by their size and shape but also by the dielectric properties of the environment and the proximity of other nanoparticles which make them most suitable candidates for colorimetric sensing applications. In this work, we developed a novel, rapid, enzyme free colorimetric assay for glucose level determination. The normal levels of glucose in human blood range from3.8 to 6.9 mM approximately, although these levels may change during the day, being lower upon fasting and reaching a peak in post-cenal states. Both high and low glycemic levels are detrimental for health status. Glucose of various physiological concentrations (3 mM-50 mM) acts simultaneously as reducing and capping agent for the gold nanoparticle synthesis from tetrachloroauric acid enabling its label free detection. The increase in glucose concentration from normal to diabetic range cause a colour change from blue to red. The localized surface plasmon resonance (LSPR) peak is shifted from 520 to 580 nm due to the agglomeration of gold nanoparticles at lower concentrations of glucose. [ABSTRACT FROM AUTHOR]