Demystifying Complex Quantum Dot Heterostructures Using Photogenerated Charge Carriers

The success of heterostructure quantum dots in optoelectronic and photovoltaic applications is based on our understanding of photogenerated charge carrier localization. However, often the actual location of charge carriers in heterostructure semiconductors is quite different from their predicted positions leading to suboptimal results. In this work, photoluminescence of Cu doped heterostructures has been used to study the charge localization of alloys, inverse type I, type II, and quasi type II core/shell structures and graded alloys. Specifically, the adeptness of this method has been assessed over a range of widely studied heterostructures like CdSe/CdS, CdS/CdSe, CdSe/CdTe, Zn_1-xCd_xSe and Zn_1-xCd_xS quantum dots systems by doping them with a small percentage of Cu. The electron and hole localization obtained from this method concurs with the pre-existing understanding in cases that have been explored before, while the internal structure of previously unknown heterostructures have been predicted.