Another reason of the choice of p-type crystalline silicon is that the electrons mobility (minority carriers) is higher about three times than the holes, so they have a big diffusion length, and then it is easy to collect them (Sze and Ng, 2007). The photovoltaic industry of silicon was therefore developed around this idea and terrestrial market is still mainly supplied today by cells in p-type silicon (Wang and Wang, 2014). Up to a certain period, all commercialized silicon solar cells were realized on p-type silicon substrate because the technology of their production was easily industrialized and accessible. This technology changed to p-type substrates because of their high resistance to space radiation, at a time when the only application for those cells was for space (Zhao et al., 2002). The first silicon solar cells were made on n-type substrates in 1950s. Furthermore, the study of the emitter led to a new structure developed recently: the selective emitter of n-type solar cell achieving efficiency of 20.20% with sheet resistance of 50 Ω/□ under the contacts and 100 Ω/□, between contacts. If all the parameters have ideal values our optimization provided an efficiency of 20.05% for homogeneous emitter with sheet resistance of 75 Ω/□. With an Al 2O 3/SiN x front side boron emitter passivation, the metallization parameters were optimized by the authors getting efficiency of 19.60%.
#PC1D MATERIAL FILES SILICON NITRIDE SIMULATOR#
To optimize this cell we have used PC2D which is a solar cell device simulator that models two-dimensional effects entirely within a Microsoft Excel spreadsheet. We studied, especially the influence of the base parameters (lifetime, resistivity and thickness), the emitter sheet resistance and the back surface field (BSF) sheet resistance, on the solar cell performances.
In this paper, we analyze the impact of various parameters on the performances of the n-type monocrystalline silicon solar cell experimented by Fraunhofer Institute for Solar Energy Systems (ISE) in Germany.