Two dimensional numerical modeling of a silicon solar cell with selective emitter configuration

This paper reports the design of a two dimensional numerical model for silicon solar cells to study a selective emitter configuration. The solar cell model has an n+ p p+ structure with a measured doping profile in the emitter and uniformly doped back surface field. The carrier flow pattern in the solar cell was analyzed by solving the diffusion equations using appropriate boundary conditions. The numerical model was developed in COMSOL by solving the Poisson equation; the current density equation and the continuity equation in each region. This model uses Fermi Dirac statistics to determine carrier densities in heavily doped regions. The simulation results indicate that if the surface doping density under the selective emitter is very high compared to the field (non-selective) region, then the width of the selective emitter fingers strongly influences Voc. But if the surface doping density under the selective emitter is only slightly high compared to the field region, then the influence on Voc is modest. This model can be used as a tool for understanding and optimizing the selective emitter configuration in the emitter region. Solar cells were fabricated with selective emitter configurations with various doping densities. Validation of the 2D model was done by comparing the simulation results with experimental results.