摘要
A comprehensive study of high efficiency In(0.46)Ga(0.54)N/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(n^+)/GaAs(p^+) and In(0.5)Ga(0.5)N(n^+)/Si(p^+) were considered.Simulations of GaAs(n^+)/GaAs(p^+)and In(0.5)Ga(0.5)N(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(J(SC)),open circuit voltage(V(OC)),fill factor(FF) and efficiency(η) for both tunnel junction designs.Using GaAs(n^+)/GaAs(p^+) tunnel junction,the obtained values of J(SC) = 21.74 mA/cm-2,V(OC)= 1,81 V,FF = 0.87 and η=34.28%,whereas the solar cell with the In(0.5)Ga(0.5)N/Si tunnel junction reported values of J(SC)= 21.92 mA/cm-2,V(OC)= 1.81 V,FF = 0.88 and η= 35.01%.The results found that required thicknesses for GaAs(n^+)/GaAs(p^+) and In(0.5)Ga(0.5)N(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.
A comprehensive study of high efficiency In(0.46)Ga(0.54)N/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(n^+)/GaAs(p^+) and In(0.5)Ga(0.5)N(n^+)/Si(p^+) were considered.Simulations of GaAs(n^+)/GaAs(p^+)and In(0.5)Ga(0.5)N(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(J(SC)),open circuit voltage(V(OC)),fill factor(FF) and efficiency(η) for both tunnel junction designs.Using GaAs(n^+)/GaAs(p^+) tunnel junction,the obtained values of J(SC) = 21.74 mA/cm-2,V(OC)= 1,81 V,FF = 0.87 and η=34.28%,whereas the solar cell with the In(0.5)Ga(0.5)N/Si tunnel junction reported values of J(SC)= 21.92 mA/cm-2,V(OC)= 1.81 V,FF = 0.88 and η= 35.01%.The results found that required thicknesses for GaAs(n^+)/GaAs(p^+) and In(0.5)Ga(0.5)N(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.