Preparation Of Silver Nanoparticles And Its Effect On Properties Of Silicon Solar Cells

Silicon is the preferred material for photovoltaic applications due to its abundance in nature, non-toxic and long-term stability. In order to reduce cost, make the solar cell thickness very thin. But low light absorption in thin film solar cells, which resulting in lower cell efficiency. Lower light absorption in the solar cells mainly due to the following two aspects, which include reflected light losses of the surface of solar cells and transmitted light losses of thin film solar cells because of its thickness is too thin. Solar cell efficiency is enhanced through increasing the light absorption of the cells due to increasing the optical pathlenth via scattering of light in the cell by plasma effect of silver nanoparticles deposited on the solar cell surface.This thesis mainly includes two parts. In the first part, Ag nanoparticles were prepared by once silver mirror reaction and annealing in the nitrogen gas. This part divided into two groups. In the first group, Ag films with different thickness were prepared by controlling the reaction time in once silver mirror reaction, then annealing in N2at400℃for one hour to form Ag nanoparticles. In the second group, the prepared Ag thin film using once silver mirror reaction were subjected to an annealing at350%for one hour in the air under the different high electric field intensity to form Ag nanoparticles. In the second part, Ag nanoparticles were prepared by once and twice silver mirror reaction with annealing in the nitrogen gas. The structures, morphologies, and optical properties of prepared silver nanoparticles were studied by using various devices (X-ray Diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), light scattering device, and Ultraviolet visible near infrared spectrophotometer). Using solar simulator(AM1.5) study the effect of morphology of the Ag nanoparticles on the performance of silicon solar cells. The following conclusions can be achieved:1. It can be seen from XRD results that, A strong (111) preferential orientation at20=38.6°is observed for all the samples. As the film thickness increases, the intensity of the (111) diffraction peak becomes stronger, indicating an improvement in the crystallinity of the Ag NPs.2. The thickness of the silver thin film was controlled by controlling the reaction time, and research results indicated that the size of the silver nanoparticles increases with increasing the thickness of the silver film. 3. The results from forward scattering measurement showed that the Ag nanoparticles prepared with20nm thick Ag film have strong light scattering, and its average particle size is240nm.4. The results from backward scattering measurement showed that the Ag nanoparticles prepared with40nm thick Ag film have the biggest intensity in bigger angle range (25°-90°), and its average particle size is390nm.5. The Transmission spectra show that silver nanoparticles with prepared thick Ag film samples have a lower transmission rate. The Ag nanoparticles prepared with5nm thick Ag thin film have the highest transmittance, and92%in whole average wavelength.6. The results of current-voltage characteristics show that the cell current density increases from28.4mA/cm2to28.6mA/cm2, an open circuit voltage remained unchanged, cell efficiency increases from12.9%from13.1%when the glass substrate with Ag nanoparticles on the surface of crystalline silicon solar cells. The cell current density increases from28.4mA/cm2to32.6mA/cm2and the cell efficiency increases from12.9%to14.4%when Ag nanoparticles prepared directly on the surface of crystalline silicon solar cells.