Simulation of double junction In0.46Ga0.54N/Si tandem solar cell

Abstract

A comprehensive study of high efficiency InGaN/Si tandem solar cell is presented. A tunnel junction (TJ) was needed to interconnect the top and bottom sub-cells. Two TJ designs, integrated within this tandem: GaAs()/GaAs() and InGaN()/Si() were considered. Simulations of GaAs(n)/GaAs(p) and InGaN (n)/Si(p) TJ I–V characteristics were studied for integration into the proposed tandem solar cell. A comparison of the simulated solar cell I–V characteristics under 1 sun AM1.5 spectrum was discussed in terms of short circuit current density (), open circuit voltage (), fill factor (FF) and efficiency () for both tunnel junction designs. Using GaAs(n)/GaAs(p) tunnel junction, the obtained values of mA/cm, V, FF = 0.87 and , whereas the solar cell with the InGaN/Si tunnel junction reported values of mA/cm, V, FF = 0.88 and . The results found that required thicknesses for GaAs(n)/GaAs(p) and InGaN (n)/Si(p) tunnel junctions are around 20 nm, the total thickness of the top InGaN can be very small due to its high optical absorption coefficient and the use of a relatively thick bottom cell is necessary to increase the conversion efficiency.