Design criteria for silicon nanostructures in silicon based triple junction solar cell

This study aims to design a novel triple-junction solar cell consisting a monolithically interconnected silicon (Si) bottom cell, quantum dots (QDs) based middle cell, and 3C-SiC top cell. The first set of efficiency limits is calculated based on the detailed balance principle. Maximum conversion efficiencies of 55, 52 and 51 % are obtained for 3C-SiC/Si–QD/Si under blackbody, AM0, and AM1.5D radiations, respectively. The maximum efficiencies are occurred in the middle cell band gap of 1.58, 1.55 and 1.6 eV for blackbody, AM0 and AM1.5D radiations, respectively. The special attention is given to the quantum dot layer to obtain a more realistic representation of such materials. Silicon quantum dots with effective band gap embedded in silicon carbide which is manageable with changing in the size of quantum dots. It is investigated with 3D Schrodinger solution. Electronic band gap for arrays of silicon quantum dots in silicon carbide is calculated. Finally, current–voltage and power-voltage characteristics of 3C-SiC/Si–QD/Si tandem solar cell for 2, 2.5, 3, 3.5, 4 and 4.5 nm QDs in diameter is simulated under one sun AM0 spectrum. The results show maximum power is achieved for 3 nm QDs. Introduced tandem solar cell is expected to improve performance of silicon based tandem solar cell.