PROGRESS IN QUANTUM-DOT INTERMEDIATE BAND SOLAR CELL RESEARCH

摘要

The intermediate band solar cell concept can be implemented in practice by means of quantum dots (QDs), but a number of challenges must be solved in order to make progress. This paper describes some of them: a) the problem of having the quantum dots embedded in the space charge region, b) the identification of the energy levels involved in the QD system and c) the weak absorption provided by the dots. Regarding the first, the inclusion of semiconductor dumping field layers sandwiching the region containing the stack of QDs is suggested as a way to drive the QDs into a flat band potential region. Concerning "b", the intermediate band is found to be separated from the conduction band by only 0.2 eV, far from the optimum value. Finally, the weak light absorption provided by the dots is discussed as a factor, together with the low intermediate band to conduction band bandgap that prevents a significant quasi-Fermi level split between the IB and the CB under normal illumination conditions.