Impact of Crystal Size, P-layer and Doping Rate on the Intrinsic Loss Rate Imposed by Shunt Resistance in the Depletion Zone and on the Rear Surface Loss Rate

Improving the performance of photovoltaic cells requires optimization of the design stages through crystallization and the percentage of impurities introduced into the n+ layer and the p layer. Doping is crucial for solar cells because it creates a transition zone, an essential structure for converting light into electricity. This process modifies the properties of crystals by adding impurities to create two zones, one with an excess of electrons (n-type) and the other with an excess of holes (p-type). This difference in charge creates an electric field that forces the electrons and holes to separate and move in opposite directions, enabling the generation of a useful electric current. However, these electrons and holes recombine at the surfaces, limiting the efficiency of the photovoltaic cell. The objective is to find a solution to reduce surface losses by studying the impact of polycrystalline crystal dimensions and the effect of the p-layer on the effect of the impurity rate of said layer on the intrinsic carrier loss rate imposed by the shunt resistance in the depletion zone and on the carrier loss rate at the rear surface. This study has made it possible to establish the mathematical expressions needed to better understand the influence of surface recombination rates. These mathematical expressions link the intrinsic loss rate in the depletion zone and the carrier loss rate at the rear surface to the impurity rate of the p-layer, the crystal dimensions and the thickness of the p-layer. The simulation results show that: if the doping concentration of the p-layer (Nb) is between 3.10 15 and 10 18 cm -3 , the intrinsic loss rate due to shunt resistance in the depletion region and the loss rate at the rear surface decrease rapidly as the impurity concentration of the p-layer (Nb) increases. Below and beyond this interval, Intrinsic loss rate imposed by the shunt resistance in the depletion zone and loss rate at the rear surface are independent of the impurity level of the p-layer. This range of doping concentrations varies with crystal size and the thickness of the p-layer. The intrinsic loss rate imposed by the shunt resistance in the depletion region decreases when the crystals are small and the p-layer is thin, while it increases when the crystals are large. As for Sb loss rate at the rear surface., it decreases with crystal size but increases with layer height p.