Dhanvir Singh

Growth of Graded SixNy ARC Films to Enhance the Efficiency of Multi-crystalline Silicon Solar Cells and Applicable in High Volume Production

Optimized silicon nitride (SiN) film, which acts as an Anti-Reflection Coating (ARC) , surface and bulk passivating layer is the key to enhance the efficiency in silicon solar cells particularly in multicrystalline silicon solar cells. In this work, SiN films with graded and non-graded profiles with different refractive indices have been prepared. The efficiency of a multi-crystalline silicon solar cell has been measured and followed by a module making process to evaluate the cell-to-module conversion power loss (CTMPL) . It has been found that an optimized graded SiN film can reduce the surface reflection in ultraviolet (UV) and visible wavelength region significantly and hence enhances the efficiency compared to single step (non-graded) recipe. To develop more insight of the experimental work, simulation was carried out using PC1D solar cell simulator and it has been observed that refractive index (n) of 2.04 is the optimum value of refractive index in single step recipe as it enhances efficiency on cell level measurement among all different single step SiN recipes. Whereas, refractive index of 2.14 is the optimum value of refractive index in graded step recipe as it produces much higher efficiency on cell level measurement among all SiN recipes and even better than single step recipe. In this research work, it has been found that graded step refractive index recipe has reduced the reflectance of SiN films, enhanced spectral response and efficiency of the solar cells and higher refractive index of SiN film corresponds to reduced CTMPL values of the modules.

Theoretical investigation of nuclear structure properties of 144Gd, 146Dy and 148Er isotones

Some N=80 isotones (144Gd, 146Dy and 148Er) have been studied by using the HFB framework and the nuclear structure properties like yrast spectra, subshell occupation numbers and quadrupole moments have been obtained. Intrinsic quadrupole moments obtained from HFB calculations show a gradual increase as one moves from 144Gd to 148Er indicating, thereby, an increase in deformation, which is in agreement with the experimental results. From the results of subshell occupation numbers, it is clear that subshells 3s1/2, 2d3/2, 2d5/2, 1g7/2 and 1h11/2 of protons are contributing towards the development of deformation as one moves from 144Gd to 148Er.

Study of odd mass 115−125Sb isotopes with the projected shell model calculations

The projected shell model (PSM) with the deformed single-particle states, generated by the standard Nilsson potential, is applied to study the negative-parity high spin states of 115–125Sb nuclei. The nuclear structure quantities like band structure and back-bending in moment of inertia have been calculated with PSM method and are compared with the available experimental data. In addition, the reduced transition probabilities, i.e., B(E2) and B(M1), are also obtained for the yrast band of these isotopes for the first time by using PSM wave function. A multi-quasiparticle structure has been predicted for 115–125Sb isotopes by the present PSM calculations.

Theoretical study of band structure of odd-mass 115,117I isotopes

By using the microscopic approach of Projected Shell Model (PSM), negative-parity band structures of odd mass neutron-rich 115,117I nuclei have been studied with the deformed single-particle states generated by the standard Nilsson potential. For these isotopes, the band structures have been analyzed in terms of quasi-particles configurations. The phenomenon of back bending in moment of inertia is also studied in the present work.

Projected shell model study of band structure of 90Nb

A systematic study of two-quasiparticle bands of the odd-odd 90Nb nucleus is performed using the projected shell model approach. Yrast band with some other bands have been obtained and back-bending in moment of inertia has also been calculated and compared with the available experimental. On comparing the available experimental data, it is found that the treatment with PSM provides a satisfactory explanation of the available data.