Generation and diffusion of excitons in silicon solar cells

We studied the phenomena of exciton generation and diffusion in a monocrystalline silicon solar cell. This study revealed two types of exciton generation: an exciton generation associated with the generation rate Gex of the excitons and a generation rate Cex/eh related to the coupling between the electron and the hole and representing the number of holes and electrons which are bonded per unit volume and per unit time to form an exciton. We have studied the exciton fraction generated as a function of the wavelength, which shows that the exciton generation is more important in the infrared. The rate of coupled exciton generation increases as a function of the coupling coefficient. Indeed, the strong coupling between the electron and the hole, synonymous with a strong bond between these two particles, favors the formation of coupled excitons. We also noted a decrease in the effective diffusion lengths as a function of the coupling coefficient. The strong bond between the electron and the hole reduces the mobility of the latter.