Size Dependent Intermediate Band Energy Levels and Absorption of Bound States in Box Shaped Quantum Dots

The quantum dot intermediate band solar cells (QD-IBSCs) have not reached the expected efficiencies yet, because their sub-bandgap photocurrents are too low. In this work, a single band k.p method is used for the calculation of bound state energy levels and absorption coefficients between bound states for the box shaped InAs/GaAs quantum dots. In this study, the effects of quantum dot parameters on intraband absorption and position of intermediate band energy levels are investigated. The results show that the bound state energy levels decrease with the increase of QD width and conduction band offset value. The QD height has less effect on absorption coefficients between bound states. Stronger absorption has been obtained for the smaller quantum dots. With the position-dependent effective mass, the bound state energy levels have decreased and the absorption coefficients slightly changed. The results found in this work will be the first step to design a realistic detailed balance model of QD-IBSCs.