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Graphene has intriguing electrical, mechanical, thermal and biological properties that are being investigated for use in composites, modern electronics, membranes, and in the industry. Also, graphene has huge biological applications. Hydroxypropyl methylcellulose (HPMC) is a widely used bio-polymer effective for various biomedical applications. As a filler in this polymer matrix, graphene oxide (GO), reduced graphene oxide (RGO) and silver (Ag) nanoparticles (NPs) can be used to improve various properties of the matrix. They are also beneficial for bio-applications like drug delivery, the production of reactive oxygen species (ROS) and the antimicrobial properties of nanocomposite films. Here we synthesize a series of polymer nanocomposites taking GO, RGO and Ag NPs as a filler by the solution mixing method and explore the comparative biological application of such composites. We choose Ag NPs as it has the superior potential for multiple drug resistance. X-ray diffraction, Fourier-transform infrared and scanning electron microscope studies are used to describe how nanocomposites are formed. Energy-dispersive X-ray and dynamic mechanical analyzer analyses were also done to check elemental percentage in nanocomposite films and mechanical properties, respectively. To check several fruitful applications, antimicrobial properties, ROS generation and in-vitro drug release study of nanocomposite films with the loading of Ketorolac Tromethamine were also performed. [ABSTRACT FROM AUTHOR]

The performance of a TOPCon solar cell depends on the properties of the dielectric material through which tunneling takes place. Common dielectric material used with n-type Si wafer is SiO2 due to its excellent passivation property for n-Si interface. Required thickness of SiO2 is ≈1.5 nm, making its fabrication quite challenging. Moreover, recently p-type TOPCon solar cell has been proposed as an alternative to p-type PERC (p-PRC) structure. So, a dielectric material different from SiO2 may act as a better tunneling cum passivation layer for p-Si wafer. In this paper, various alternative tunneling/passivating dielectric layers like Si3N4, Al2O3, HfO2 and ZrO2 have been discussed. The cell performances as well as the critical dielectric thicknesses of all these materials have been simulated using the three-dimensional Sentaurus TCAD software. It has been found that the critical dielectric thickness for optimum cell performances depends strongly on the tunneling effective mass of the majority carriers, dielectric barrier at the dielectric/Si interface for the majority carriers and fixed charges in the dielectric. We have also used the simulation for an arbitrary generic dielectric and studied the dependence of its critical thickness (tcritical) on the three parameters mentioned above. [ABSTRACT FROM AUTHOR]

Passivated emitter rear contact (PERC) solar cell involves upgraded adaptation of technology over the existing silicon wafer-based aluminium back surface field (Al-BSF) solar cell. The lower efficiency of Al-BSF is caused by a few drawbacks e.g. higher rear surface recombination and weaker electric field at the rear surface. These technical shortcomings can be mitigated by incorporating field-effect passivation (FEP) layer viz. aluminium oxide (Al2O3) at the rear surface with a capping layer of SiNX on it. Conventionally two new processing steps utilizing two expensive equipments, green laser (532 nm) for laser ablation of the FEP and SiNX capping layer stack at the rear surface and single side etcher for rear side polishing of wafer are used for manufacturing of PERC cells. In this paper, we have shown that instead of these two new expensive processing equipments we can use the IR laser (1024 nm) and RIE etcher, which are commonly available for Al-BSF manufacturing line, for the fabrication of PERC solar cells. Using p-type wafers of rather modest quality (minority carrier lifetime of ≥10 µs) we have demonstrated improvement of the efficiency from 18.71 to 19.62% and enhancements in VOC and JSC from 628 to 646 mV and 38.59 mA/cm2 to 39.82 mA/cm2, respectively. A thorough root-cause analysis has been carried out to optimize the two new approaches within the existing Al-BSF line for the fabrication of PERC solar cell. [ABSTRACT FROM AUTHOR]

Graphene and its related materials are important areas of research in recent years owing to their unique properties. The wide-range industrial application of graphene-related compounds has led to the development of novel and simple methods for the synthesis of graphene. In this paper, an environmentally friendly green synthesis for the partial reduction of graphene oxide (GO) to reduced GO (RGO) in a cost-effective single-step mechanism was reported. The method completely avoids the use of toxic and environmentally harmful reducing agents commonly used in the chemical reduction of GO to obtain RGO. The reduction of GO was carried out using aqueous leaf extracts of Paederia foetide L. The prepared GO and green RGO were characterized by ultraviolet-visible, Raman and Fourier transform infra-red spectroscopic analysis which showed a clear indication of the partial removal of oxygen-containing groups from the GO and the formation of RGO. The morphology of the green RGO was characterized by transmission electron and scanning electron microscopy. Dynamic light scattering was used for zeta potential measurement and correlated with the morphology of the sheets. Electrical conductivity was also measured to check the extent of reduction of GO to RGO. [ABSTRACT FROM AUTHOR]