Theoretical study on potential performance of lattice-matched monolithic GaNP/GaNAsP/Si triple-junction solar cell

A Si-based lattice-matched monolithic triple-junction (TJ) cell is presented by employing dilute nitride alloy GaN(0.02)P(0.98)for top cell and III-N-V quaternary compound GaNAsP with a tunable bandgap for middle cell. Based on different models about the surface recombination velocity (S) and the minority carrier lifetime (tau) of III-V subcells, the theoretical performance of GaNP/GaNAsP/Si TJ cells is calculated with variable GaNAsP bandgaps and adjusted thicknesses of base layer in top and middle cells. The conversion efficiency of TJ cell has a strong relationship withSand tau due to the obvious influence ofSand tau on the quantum efficiencies of III-V subcells. By adopting a superior model withSof electrons as 100 cm center dot s(-1)and tau of electrons as 10 ns, a maximum efficiency of 41.53% is obtained when GaNAsP bandgap is 1.473 eV, and the optimum base thicknesses of top and middle cells are 1.2 mu m and 2.0 mu m, respectively. The calculation method and results would contribute to the study of multi-junction solar cell composed of III-N-V materials and low-cost Si substrate.