Study On Simulation,Preparation And Properties Of Crystalline Silicon Solar Cell Based On Silver And Carbon Nanotubes Array

The main challenge with the use of silicon for photovoltaics is that silicon is not a strong absorber of sunlight.Increasing absorption of light in the absorber layers is critical issue for achieving high efficiency silicon solar cells.Due to the light manipulation ability of nanostructures,sub-wavelength nanostructures light trapping strategies have been employed on the front of silicon with patterning of dielectric materials.Light trapping with sub-wavelength nanostructures involves coupling light into localized resonant modes and guided resonance modes in active region to increase absorption.In this paper,the silver nanoparticles?Ag NPs?and multi-walled carbon nanotubes?MWCNT?array were selected as the basic light trapping materials.The crystalline silicon solar cells with the structures of nanoparticles and periodic subwavelength grating were prepared.The optical and photovoltaic properties of the sub-wavelength nanostructures were investigated in experiments and simulations.The mechanism for the enhancement of photovoltaic performance was discussed by combining the local surface plasmon resonance effect and the optical effect of guided wave.Firstly,titanium dioxide?TiO₂?dielectric layer and silver?Ag?film were prepared on the surface of the p-n crystalline silicon by magnetron sputtering,and then the crystalline silicon solar cell of Ag NPs/TiO₂ was prepared by the one-step process of sintering and annealing.The different sizes of silver nanoparticles were investigated,it is found that the silver nanoparticles 160 nm in diameter combining with titanium dioxide dielectric layer made the efficiency increased by 9.9%,and the short circuit current density increased by7.7%.In addition to the local surface plasmon resonance effect,the TiO₂ layer plays an important role in improving the photovoltaic performance of the crystalline silicon solar cells.Comsol and Matlab were used for simulation and calculation to further study the mechanism of light trapping and efficiency increasing.The simulation results agreed well with the experimental results.Secondly,the gas flow field in the reaction chamber was simulated by Fluent,and the impacts of gas flow field on the morphologies of MWCNTs were investigated.The catalyst was prepared by magnetron sputtering and spin transfer method,and then the aligned multi-walled carbon nanotube arrays were prepared by chemical vapor deposition.The two methods of catalysts preparation were compared and the impacts of the catalysts on morphology were investigated by experiments.Carbon nanotube arrays are effective to reduce the reflectance due to their nano-scale holes,so there are great potential for photovoltaic in light trapping and efficiency increasing.Then,the optical property of the crystalline silicon solar cells with grating structures of MWCNT,MWCNT@TiO₂ and MWCNT@Ag were investigated by Comsol,and it is found that the reflectance is the lowest and absorptance is the highest when the diameter is70 nm,the space is between 75 nm and 125 nm,the coating thicknesses are 40 nm and 60nm respectively.The photovoltaic performance of crystalline silicon solar cells with different light trapping structures was calculated by Matlab,it is found that the ideal efficiency and the short circuit current density of the crystalline silicon solar cells with the composite structures are increased significantly.Finally,the crystalline silicon solar cells with grating structures of MWCNT@TiO₂ and MWCNT@Ag were prepared by magnetron sputtering,it is found that the photovoltaic performance of the crystalline silicon solar cells with the composite structure are increased.The photovoltaic performance of MWCNT@Ag is higher than the photovoltaic performance of MWCNT@TiO₂.The optical absorption of the crystalline silicon solar cells can be enhanced through Fabry-Perot microcavity resonance due to the grating structures of subwavelength.While the metal gratings can further improve the optical absorption of the crystalline silicon solar cells by using the coupling effect of Fabry-Perot microcavity resonance and local surface plasmon resonance.As a consequence,the efficiency of the crystalline silicon solar cells was increased by the light trapping.