Orientation Modulated Hot Charge Carrier Transport in Quantum Dot Solids

Advances in the synthesis of colloidal quantum dots (QDs) have made it possible to engineer the QDs film at the atomistic level, including the control over how QDs are oriented in QD solids. Understanding how the QD orientation impacts charge carrier transport in QD solids is central to the rational design and optimization of QDs devices. Using first-principles quantum dynamics simulations, we investigated the transfer process of excited electrons and holes across silicon QDs with different orientations. We considered how a doubly-bonded oxygen defect at the QD surface impacts the transfer since it is one of the most commonly found and electronically active defects in experiments. Excited electron transfer between the QDs was found to be quite sensitive to the QD orientation. Excited hole, on the other hand, does not show such strong dependence on the orientation. Our results highlight the importance of the atomistic details of colloidal QDs for understanding charge transport properties.