Two dimensional numerical modeling of a silicon solar cell with deep contacts in the emitter

The influence of front contacts deep into the emitter region on the performance of a Si solar cell was calculated on the basis of a 2-D numerical modeling of an n₊-p crystalline silicon solar cell. The emitter is n-type doped with a Gaussian profile. The base is p-type uniformly doped. 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 both the regions. The numerical model was verified with the PC1D model by covering the whole front emitter surface with a transparent contact. The model after verification was used to determine the effects of the size and depth of the front contacts in the emitter region on the short circuit current and open circuit voltage of the solar cell. The results indicated a reduction in the open circuit voltage with increase in depth of the contact into the emitter region, as expected. This new model can be used a tool for understanding and optimizing the interaction of the front contacts with the emitter region.