Method for optimizing the parameters of heterojunction photovoltaic cells based on crystalline silicon

An approach is proposed to calculate the optimal parameters of silicon-based heterojunction solar cells whose key feature is a low rate of recombination processes in comparison with direct-gap semiconductors. It is shown that at relatively low majority-carrier concentrations (N_d ～ 10¹⁵ cm^–3), the excess carrier concentration can be comparable to or higher than N_d. In this case, the efficiency η is independent of N_d. At higher N_d, the dependence η(N_d) is defined by two opposite trends. One of them promotes an increase in η with N_d, and the other associated with Auger recombination leads to a decrease in η. The optimum value N_d ≈ 2 × 10¹⁶ cm^–3 at which η of such a cell is maximum is determined. It is shown that maximum η is 1.5–2% higher than η at 10¹⁵ cm^–3.